Physical fitness in Ehlers-Danlos
Syndrome Hypermobility type
A follow-up study
Sofie Gyssels, Thuline Heyerick, Katrijn Janssens Student number: 01306117, 01303954, 01304088
Supervisors: Dr. Lies Rombaut, Prof. Dr. Patrick Calders
A dissertation submitted to Ghent University in partial fulfillment of the requirements for the degree of Master of Science in Rehabilitation Sciences and Physiotherapy
Academic year: 2017 - 2018
Physical fitness in Ehlers-Danlos
Syndrome Hypermobility type
A follow-up study
Sofie Gyssels, Thuline Heyerick, Katrijn Janssens Student number: 01306117, 01303954, 01304088
Supervisors: Dr. Lies Rombaut, Prof. Dr. Patrick Calders
A dissertation submitted to Ghent University in partial fulfillment of the requirements for the degree of Master of Science in Rehabilitation Sciences and Physiotherapy
Academic year: 2017 - 2018
Acknowledgments
This research was conducted during the academic years 2016-2017 and 2017-2018 by Sofie Gyssels,
Thuline Heyerick and Katrijn Janssens to obtain a master degree in ‘Physiotherapy and Rehabilitation
Sciences’ at Ghent University. We would like to express our sincere gratitude to the following people
who had their share in accomplishing this master thesis.
First of all, we would like to thank our promotor and copromotors; Dr. Lies Rombaut, Prof. Patrick
Calders and Marie Coussens for their feedback and mentoring. They supported and steered us
through this two-year project with their knowledge and patience. Especially Dr. Rombaut, assigned
as our promotor, who was always willing to meet and discuss problems or to help us when
necessary.
Our gratitude also goes to the Department of Physical therapy and Rehabilitation Sciences of Ghent
University to provide us with the laboratories and equipment we required for our research. Thanks
are also extended for the cooperation with the Amsterdam University of Applied Sciences.
Furthermore, we would like to thank the patients who participated in this study.
Finally, sincere thanks to our friends and families for their help, support and involvement during the
process.
Sofie Gyssels
Thuline Heyerick
Katrijn Janssens
Ghent, May 2018
Table of contents
Acknowledgments ................................................................................................................................... 4
Table of contents ..................................................................................................................................... 5
Table list .................................................................................................................................................. 7
Figure list ................................................................................................................................................. 8
List of abbreviations ................................................................................................................................ 9
Abstract ................................................................................................................................................. 10
Abstract in Dutch ................................................................................................................................... 11
Introduction ........................................................................................................................................... 12
Materials and methods ......................................................................................................................... 14
Subjects ............................................................................................................................................. 14
Procedures......................................................................................................................................... 14
Measurements .................................................................................................................................. 15
Diagnostic criteria .......................................................................................................................... 15
Clinical measurements .................................................................................................................. 16
Questionnaires .............................................................................................................................. 20
Statistical analyses ............................................................................................................................. 20
Results ................................................................................................................................................... 22
Subjects ............................................................................................................................................. 22
Muscle strength ................................................................................................................................. 23
Pulmonary function ........................................................................................................................... 23
Aerobic capacity ................................................................................................................................ 24
Questionnaires .................................................................................................................................. 24
Discussion .............................................................................................................................................. 25
Summary of the results ..................................................................................................................... 25
Muscle strength ................................................................................................................................. 25
Aerobic capacity ................................................................................................................................ 26
Pulmonary function ........................................................................................................................... 26
Strengths and limitations .................................................................................................................. 27
Future research ................................................................................................................................. 27
Conclusion ............................................................................................................................................. 28
References ............................................................................................................................................. 29
Abstract in lekentaal .............................................................................................................................. 33
Bewijs van indiening bij het ethisch comité .......................................................................................... 34
Table list
Table 1: Villefranche criteria EDS-HT [4] ............................................................................................... 14
Table 2: Diagnostic criteria hEDS [7] ..................................................................................................... 15
Table 3: Spirometry ............................................................................................................................... 18
Table 4: Clustered variables .................................................................................................................. 18
Table 5: Beighton score [34] .................................................................................................................. 19
Table 6: Bulbena score [35] ................................................................................................................... 19
Table 7: Subdivision groups ................................................................................................................... 21
Table 8: Subjects’ characteristics .......................................................................................................... 22
Table 9: Muscle strength ....................................................................................................................... 23
Table 10: Results questionnaires ........................................................................................................... 24
Figure list
Figure 1: Joint Hypermobility ................................................................................................................ 12
Figure 2: HHD hip flexion ....................................................................................................................... 17
Figure 3: Mouth Pressure Monitor 100® ............................................................................................... 18
Figure 4: OneFlow® ............................................................................................................................... 18
List of abbreviations
6MWT Six minutes walk test
30s CRT 30 seconds chair rise test
BMI Body Mass Index
CIS20 Checklist Individual Strength
EDS Ehlers-Danlos Syndrome
EDS-HT Ehlers-Danlos Syndrome Hypermobility type
FEV1 Forced expiratory volume
FEV1/FVC Tiffeneau index
FVC Forced vital capacity
GJH Generalized joint hypermobility
HAQ Health assessment questionnaire
hEDS Hypermobile EDS
HHD Hand-held dynamometry
MEP Maximal expiratory pressure
MIP Maximal inspiratory pressure
PEF Peak expiratory flow
SD Standard deviation
SF-36 Short Form (36)
SPSS Statistical Package for Social Sciences
SRT Steep ramp test
T1 First testing moment (2012)
T2 Second testing moment (2017)
10
Abstract
Objectives: To investigate the evolution or changes in various physical fitness parameters in Ehlers-
Danlos Syndrome Hypermobility type (EDS-HT) patients by means of a five-year follow-up
measurement.
Study design: Follow-up study
Subjects and methods: Twenty-two women diagnosed with EDS-HT participated in this follow-up
study. Assessment was performed at two testing moments, respectively in 2012 (T1) and in 2017
(T2). The protocol existed of clinical measurements and questionnaires. Data about muscle strength,
pulmonary function and aerobic capacity was obtained from the 30 second chair rise test (30s CRT),
hand-held dynamometry (HHD), six minutes walk test (6MWT), steep ramp test (SRT) and two
spirometry tests (mouth pressure monitoring and peak flow meter). Additionally, possible
confounding factors were explored.
Results: A significantly increased hip flexion strength, ankle dorsiflexion strength and total muscle
strength were found at T2 compared to T1. In the pulmonary function tests, only significantly
reduced peak expiratory flow (PEF) values were seen. Furthermore, a significantly increased
maximum wattage on the SRT was noted.
Conclusion: To our knowledge, this follow-up study was the first to investigate the evolution of the
physical fitness in patients suffering from EDS-HT. It is plausible that the increased total muscle
strength and maximum wattage on the SRT were a result of the habitual physical activity and the
regularly received sessions of physiotherapy. However, no univocal consensus concerning the
physical fitness of EDS-HT patients could be found. Therefore, further research over a longer period
on the physical fitness level of patients suffering from EDS-HT seems indicated.
Key words: Ehlers-Danlos Syndrome Hypermobility type, physical fitness, evolution, muscle strength,
aerobic capacity, pulmonary function
11
Abstract in Dutch
Doelstelling: Aan de hand van een vijf jaar durende follow-up studie werden de evolutie of
veranderingen in verschillende parameters van fysieke fitheid onderzocht bij patiënten die lijden aan
het Ehlers-Danlos Syndroom Hypermobiel type (EDS-HT).
Onderzoeksdesign: Follow-up studie
Deelnemers en methode: Tweeëntwintig vrouwen, gediagnosticeerd met EDS-HT, hebben aan deze
studie deelgenomen. Het testprogramma bestond zowel in 2012 (T1) als in 2017 (T2) uit klinische
metingen en vragenlijsten. Data in verband met de spierkracht, longfunctie en aerobe capaciteit
werd verkregen met behulp van de 30 second chair rise test (30s CRT), hand-held dynamometrie
(HHD), 6 minuten wandeltest (6MWT), steep ramp test (SRT) en twee spirometrie testen (mouth
pressure monitoring en peak flow meter). Daarnaast werd de invloed van mogelijke covariaten op de
evolutie nagegaan.
Resultaten: Er werd een significante stijging waargenomen in de heupflexie kracht, enkeldorsiflexie
kracht en totale spierkracht op T2 vergeleken met T1. Betreffende de longfunctietesten, werden er
enkel significant gedaalde peak expiratory flow (PEF) waarden gevonden. Daarenboven was het
maximale vermogen op de SRT significant gestegen.
Conclusie: Voor zover geweten was deze follow-up studie de eerste die de evolutie van de fysieke
fitheid bij patiënten lijdend aan EDS-HT in kaart bracht. Het is aannemelijk dat de gestegen totale
spierkracht en het maximale vermogen op de SRT het resultaat zijn van de frequent uitgevoerde
fysieke activiteit en de kinesitherapie sessies op regelmatige basis. Er kon echter geen eenduidig
besluit geformuleerd worden in verband met de evolutie van de fysieke fitheid bij EDS-HT patiënten.
Verder onderzoek gedurende een langere periode lijkt noodzakelijk te zijn.
Sleutelwoorden: Ehlers-Danlos Syndroom Hypermobiel type, fysieke fitheid, evolutie, spierkracht,
aerobe capaciteit, longfunctie
12
Introduction
The Ehlers-Danlos Syndrome (EDS) is a heterogeneous group of inherited disorders of the connective
tissue [1-4]. The connective tissue is responsible for the solidity of the structures in bones, joints, skin
and blood vessels. It is constituted of an extracellular matrix, composed of collagen and elastin, as
well as proteoglycans and glycoproteins. In EDS, the formation of collagen type I, III, V and XII is
affected. Thus, a wide range of clinical manifestations is caused [2, 5-7].
Most common symptoms are joint hypermobility, hyperextensibility of the skin and tissue fragility
[7]. In the Villefranche classification of 1997, six subtypes were defined [4]. The classical, vascular and
hypermobility type are the most common types of EDS [8]. The diagnosis of the hypermobility type of
EDS (EDS-HT) is not supported by any confirmatory laboratory or genetic test, but is strictly based on
anamnesis and clinical signs. The major clinical signs to diagnose EDS-HT are: hyperextensible and/or
smooth, velvety skin and generalized joint hypermobility (based on a Beighton score ≥ 5/9). Joint
dislocation, chronic joint/limb pain and a positive family history are the minor criteria. These criteria
are also shown in Table 1 (see methodology).
In April 2017, new criteria were proposed for the diagnosis of EDS-HT at which EDS-HT was redefined
as hypermobile EDS (hEDS) with stricter clinical diagnostic criteria [7]. For this study, patient
recruitment was performed in 2012 (see methodology). Because new criteria were formulated post
patient selection, patients in this follow-up study are still considered as patients with the
hypermobility type of EDS (EDS-HT) according to the Villefranche criteria.
Although not defined in the diagnostic criteria for hEDS, muscular involvement and fatigue have been
suggested to be a common associated feature in EDS-HT patients [9-11]. Consequently, physical
activity and physical fitness levels may be reduced as well. Therefore, a systematic review was
performed in 2016-2017 and in February 2018 all databases were searched again to collect
Figure 1: Joint Hypermobility Figure 2: HHD hip flexionFigure 3: Joint Hypermobility
13
information about muscle function, physical activity and physical fitness in patients with EDS-
HT/hEDS.
The World Health Organization defined physical activity as “any bodily movement produced by
skeletal muscles that requires energy expenditure” [12]. Some studies show a decreased physical
activity level in EDS-HT patients compared to healthy controls [13-17].
Physical fitness is defined as "the ability to carry out daily tasks with vigor and alertness, without
undue fatigue with ample energy to enjoy leisure-time pursuits and to meet unforeseen
emergencies” by Caspersen et al. [18]. In order to gain an insight into the health-related fitness level,
cardiorespiratory endurance, muscular endurance, muscular strength, body composition and
flexibility measurements are required. Physical fitness is the result of a complex interaction between
these components as well as agility, balance, coordination, speed, power and reaction time, known
as skill-related fitness [18].
In the majority of the studies, significantly reduced muscle strength and muscle strength endurance
in EDS-HT patients was found in comparison to healthy controls [13-15, 19, 20]. However, two
authors illustrated no significant difference in patient groups [9, 21]. The literature concerning
aerobic capacity in EDS-HT patients is very scarce. Scheper et al. found a reduced score on the six
minutes walk test (6MWT) and 30 second chair rise test (30s CRT) in EDS-HT patients in comparison
to healthy controls (p < 0.0001) [13]. Spirometry and lung function tests are also rarely studied in
EDS-HT patients. Ayres et al. showed a reduced gas transfer coefficient [22], while Morgan et al.
found an increased prevalence of asthma in EDS patients compared to healthy controls. Other
striking differences were an increase in lung volumes, a reduction in gas transfer and an increased
tendency of the airways to collapse [23]. To date no univocal consensus could be found regarding
physical fitness in EDS-HT patients.
Furthermore, it is currently not known how and to what extent physical fitness levels evolve during
time in EDS-HT patients. Nevertheless, changes in cardiorespiratory fitness parameters, muscle
strength and endurance, may have an important impact on functionality, physical activity and quality
of life in this patient population.
Therefore, the objective of this study was to investigate the evolution or changes in various physical
fitness parameters in EDS-HT patients by means of a five-year follow-up measurement.
14
Materials and methods
Subjects
At baseline in 2012 (T1), 26 adult patients diagnosed with EDS-HT participated. Due to the female
predominance, only women were included in the study [4]. Patient selection was performed in the
Centre for Medical Genetics at the Ghent University Hospital. The patients were recruited based on
the Villefranche criteria (see Table 1) because the new criteria were formulated post patient
selection [4]. In 2017 (T2), subjects were invited again to participate in the second testing moment by
e-mail, mail and phone. Twenty-two patients of the initial group of 26 participated. One patient was
not able to participate because of medical reasons and three patients declined because of their job.
Consequently, this study focused on 22 patients with EDS-HT who participated at T1 and T2 in the
study.
Table 1: Villefranche criteria EDS-HT [4]
Villefranche Criteria EDS-HT Major criteria Minor criteria
Skin involvement (hyperextensibility and/or smooth velvety skin) Recurring joint dislocations
Generalized joint hypermobility Chronic joint/limb pain
Positive family history
Procedures
The study was performed in cooperation with the Amsterdam University of Applied Sciences. The
study protocol was reviewed and approved by the Ethical Committee of the Ghent University
Hospital. Prior to the testing, the purposes and procedures were explained and informed consent
was obtained from all participants. All tests were conducted on one day at the department of
Rehabilitation Sciences and Physiotherapy at the Ghent University Hospital. Total duration of the test
protocol was three hours.
The complete testing protocol consisted of three parts: diagnostic criteria, clinical measurements and
questionnaires. This master thesis focused on questionnaires and measurements that are related to
the aspect of physical fitness in EDS-HT patients, which are explained in detail below.
15
Measurements
Diagnostic criteria
Previous to the clinical measurements, participants were re-evaluated for the new diagnostic criteria
(see Table 2).
Table 2: Diagnostic criteria hEDS [7]
Criterion 1
Generalized joint hypermobility based on the Beighton score cut-off
Pre-pubertal children and adolescents: ≥ 6 Pubertal to 50 years: ≥ 5 > 50 years: ≥ 4
OR Beighton score of 1 point below the cut-off and a positive five-point questionnaire
AND
Criterion 2 ≥ 2 of the 3 features
A. Systemic manifestations of a more generalized connective tissue disorder (≥ 5)
1. Unusually soft or velvety skin 2. Mild skin hyperextensibility 3. Unexplained striae such as striae distensae or
rubrae at the back, groins, thighs, breasts and/or abdomen in adolescents, men or prepubertal women without a history of significant gain or loss of body fat or weight
4. Bilateral piezogenic papules of the heel 5. Recurrent or multiple abdominal hernia(s) (e.g.,
umbilical, inguinal, crural) 6. Atrophic scarring involving at least two sites and
without the formation of truly papyraceous and/or hemosideric scars as seen in classical EDS
7. Pelvic floor, rectal, and/or uterine prolapse in children, men or nulliparous women without a history of morbid obesity or other known predisposing medical condition
8. Dental crowding and high or narrow palate 9. Arachnodactyly, as defined in one or more of the
following a. Positive wrist sign (Steinberg sign) on both
sides b. Positive thumb sign (Walker sign) on both
sides 10. Arm span-to-height ≥ 1.05 11. Mitral valve prolapse mild or greater based on
strict echocardiographic criteria 12. Aortic root dilatation with Z-score > +2
B. Positive family history, with one or more first degree relatives independently meeting the current diagnostic criteria for hEDS
16
C. Musculoskeletal complications (≥ 1)
1. Musculoskeletal pain in two or more limbs, recurring daily for at least 3 months
2. Chronic, widespread pain for ≥ 3 months 3. Recurrent joint dislocations or frank joint
instability, in the absence of trauma (a or b) a. Three or more atraumatic dislocations in the
same joint or two or more atraumatic dislocations in two different joints occurring at different times
b. Medical confirmation of joint instability at two or more sites not related to trauma
AND
Criterion 3
All of the following pre-requisites must be met
1. Absence of unusual skin fragility, which should prompt consideration of other types of EDS.
2. Exclusion of other heritable and acquired connective tissue disorders, including autoimmune rheumatologic conditions. In patients with an acquired connective tissue disorder, additional diagnosis of hEDS requires meeting both Features A and B of criterion 2. Feature C of criterion 2 (chronic pain and/or instability) cannot be counted towards a diagnosis of hEDS in this situation.
3. Exclusion of alternative diagnoses that may also include joint hypermobility by means of hypotonia and/or connective tissue laxity. Alternative diagnoses and diagnostic categories include, but are not limited to, neuromuscular disorders, other heritable connective tissue disorders, and skeletal dysplasias. Exclusion of these considerations may be based upon history, physical examination, and/or molecular genetic testing, as indicated.
Clinical measurements
30 Second chair rise test (30s CRT)
The 30s CRT was used to evaluate the functional lower extremity performance. The test measured
the number of chair stands a person was able to perform in 30 seconds. An attempt was taken into
account if one cycle of standing up and sitting down was completed. Support of the hands was not
allowed. A low score indicates a reduced lower limb strength and function. A moderate reliability
(r = 0.89) and validity (r = 0.77) for the 30s CRT was reported by Jones et al. in adults over the age of
60 years [24].
17
Hand-held dynamometry (HHD)
HHD was performed to evaluate isometric muscle strength.
Shoulder abduction, elbow flexion, hip flexion, knee
extension, ankle dorsiflexion and grip strength were examined
in a standardized starting position. Three repetitions were
completed bilaterally. The score taken into account was the
mean of the highest values of both sides. The total muscle
strength score was the sum of these six mean values. The
reliability and validity of hand-held dynamometry are likely to
be high. Although, in literature, few inconsistencies are
described [25-27].
Six minutes walk test (6MWT)
The goal of the 6MWT is to walk as far as possible in a 15-m-long free passage within six minutes. The
covered distance indicates the functional exercise capacity of the patient and suggests the ability to
operate in activities of daily living [28]. During the test the patient was motivated by the researcher
every minute with standardized encouragements. The participant was allowed to repose anytime,
but was encouraged to continue as soon as possible. The 6MWT was found to be a reliable and
reproducible test in patients suffering from Scleroderma lung disease [29].
Steep ramp test (SRT)
Exercise capacity was assessed with the SRT, a submaximal test on a cycle ergometer (Ergo-fit® Cycle
400). Saddle height was adjusted to the length of the legs. Heart rate was measured by a heart rate
monitor with a Polar chest strap. First, the pre-test heart rate was registered. Afterwards, the patient
started with a three minutes warming-up without resistance. Subsequently, the researcher increased
the resistance with 25 Watt every ten seconds. A cadence of 70-80 rotations per minute had to be
maintained. The test was terminated if the cadence was below 60 rotations per minute and was
followed by a two minutes cooling-down. Maximum wattage, post-test heart rate and BORG scale
were registered. According to Bongers et al. the SRT is a valid (r = 0.958) and reliable test (r = 0.986)
in healthy children and young adults [30].
Spirometry
Maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), peak expiratory flow (PEF),
forced vital capacity (FVC), forced expiratory volume (FEV1) and the Tiffeneau Index (FEV1/FVC) were
evaluated to assess respiratory function and muscle strength (see Table 3).
Figure 4: HHD hip flexion Figure 5: HHD hip flexion
18
Table 3: Spirometry
Spirometry
Value Description
Peak expiratory flow (PEF) Maximum flow of the forced and complete expiration after a forced and complete inspiration [31]
Forced vital capacity (FVC) The volume delivered in the first second of a FVC manoeuvre [32]
Forced expiratory volume (FEV1) The volume of air that could be forcibly expired in one second, after forced and complete inspiration [32]
Tiffeneau Index (FEV1/FVC) Correspondence between the forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) [33]
The patient was tested in sitting position, wearing a nose
clip. The Mouth Pressure Monitor 100® was used to
register the MIP and MEP values. The subject was asked to
respectively breathe in and breathe out as forceful as
possible. The aim of the test was to have a peak value
within the first three seconds. This procedure was
repeated three times and the highest value was taken into
account. If the score of the third attempt was the maximum value or if a
difference of more than 10% between the two highest scores was present, a
fourth measurement was performed. PEF, FVC, FEV1 and the Tiffeneau Index
were assessed using a peak flow meter (OneFlow®). Two repetitions of a
maximum forced and complete expiration after a forced and complete
inspiration were performed.
Incorporated variables were grouped into three major clusters (see Table 4).
Table 4: Clustered variables
Clustered variables
Strength components 30s CRT, HHD, MIP, MEP and 6MWT
Pulmonary function components PEF, FVC, FEV1 and FEV1/FVC
Aerobic components 6MWT and SRT
Figure 7: Mouth Pressure Monitor 100®
Figure 6: OneFlow®
19
Body composition
Body composition was measured using the Tanita BC 418. This included Body Mass Index (BMI), fat
mass, lean body mass and fat percentage. Furthermore, body height and body weight were
measured. Body composition can be considered as a possible confounding factor.
Generalized joint hypermobility (GJH)
To evaluate GJH, the Beighton and Bulbena score were used (see Table 4 and 5). GJH can be
considered as a possible confounding factor.
Table 5: Beighton score [34] Beighton score Left Right 1 Passive dorsiflexion of the little fingers beyond 90° 0/1 0/1
2 Passive apposition of the thumbs to the flexor aspects of the forearms 0/1 0/1
3 Hyperextension of the elbows beyond 10° 0/1 0/1 4 Hyperextension of the knees beyond 10° 0/1 0/1
5 Forward flexion of the trunk, with knees straight, so that the palms of the hands rested easily on the floor 0/1
Table 6: Bulbena score [35] Bulbena score Left Right
1 Passive apposition of the thumb to the flexor aspect of the forearm < 21mm 0/1 0/1
2 Palm of the hand resting on the table, the passive dorsiflexion of the fifth finger is ≥ 90° 0/1 0/1
3 Passive hyperextension of the elbow ≥ 10° 0/1 0/1
4 Shoulder external rotation ≥ 85° with the upper arm touching the body and the elbow fixed at 90° 0/1 0/1
5 Passive hip abduction ≥ 85° 0/1 0/1 6 Patellar hypermobility 0/1 0/1
7 Knee flexion allows the heel to make contact with the buttock in prone position 0/1 0/1
8 Passive dorsiflexion of the ankle > 20° and excessive eversion 0/1 0/1
9 Dorsiflexion of the toe over the diaphysis of the fifth metatarsal is ≥ 90° 0/1 0/1
20
Questionnaires
Following questionnaires were used and considered as possible confounding factors and therefore
briefly explained.
A follow-up questionnaire created by the researchers was used to assess personal information,
medical history, therapy, medication, physical activity, injuries and complaints over the past five
years.
The Health Assessment Questionnaire (HAQ) evaluates the health status of the patient. Different
activities were scored from 0 (‘independently without problems’) to 4 (‘unable to do independently’).
According to the review of Ramey et al., the validity (r = 0.71-0.88) and reliability (r = 0.87-0.96) are
sufficient [34].
Physical and mental health can be derived from the eight items of the Short Form 36 (SF-36), which is
a reliable and valid tool according to the study of Aaronson et al. and Colleen et al. [35, 36].
Subjective fatigue was evaluated by the Checklist Individuele Spankracht (CIS20). This questionnaire
contains 20 questions, divided into four subscales. For this review, solely the item fatigue was
included. According to Worm-Smeitink et al., the Dutch version of this questionnaire is a valid and
reliable tool [37].
Statistical analyses
Data was statistically analyzed using Statistical Package for Social Sciences (SPSS), version 25. To
evaluate the distribution of the data, the Shapiro-Wilk test was performed. If the data did fulfill the
assumptions of a normal distribution, parametric tests were used for statistical analysis. Descriptive
statistics are shown as the mean ± standard deviation (SD) for continuous data and as percentages or
absolute frequencies for categorical data. To compare the subject characteristics and the data of the
strength components, pulmonary function components and aerobic components between T1 and T2,
Paired-Samples T tests were performed. Delta scores were calculated (difference scores T2 – T1). If
the delta scores fit between the range of ± 1 SD of the mean delta scores, the results between T2 and
T1 are quite the same. If the individual delta scores are lower or higher than the range, the results
between T2 and T1 are interpreted as significantly decreased or increased. Three groups were made
based on this outcome (“improved”, “equal”, “decreased”).
21
Table 7: Subdivision groups Subdivision groups “Decreased” group Difference score < mean -1 SD “Equal” group Mean -1 SD < difference score < mean +1 SD “Improved” group Difference score > mean +1 SD
Correlations between continuous data were performed using the Pearson correlation, and for
categorical data the Fisher’s Exact Test was used.
P values less than 0.05 were considered as statistically significant.
22
Results
Subjects
Twenty-two women with an average age of 48 years (range 29-62 years) at T2 participated in this
study. Seven participants (n = 7/22, 31.8%) fulfilled the new diagnostic criteria and thus the diagnosis
of hEDS was confirmed in only one third of the patients. The characteristics of the study sample are
summarized in Table 7.
Table 8: Subjects’ characteristics
T1 T2 Paired-Samples T test
Body Length (cm) 165.45 ± 7.01 164.73 ± 7.17 p = 0.006* ↓
Body Weight (kg) 76.36 ± 13.99 79.75 ± 17.68 p = 0.018* ↑
Body Mass Index (kg/m2) 27.86 ± 4.70 29.38 ± 6.32 p = 0.006* ↑
Body fat (percentages) 37.76 ± 6.33 42.37 ± 7.99 p < 0.001** ↑
Beighton Score 4 ± 2.49 4.32 ± 2.69 p = 0.609
Values are the mean ± SD; * p < 0,05; ** p < 0,001; ↑ significant increase; ↓ significant decrease
Furthermore, three quarters of the participants (n = 17/22, 77.3%) reported visiting a physiotherapist
at least once a week. Nearly half of the patient group (n = 10/22, 45.5%) used a walking aid in the
past five years.
Sixteen patients performed some kind of sports during the follow-up period (n = 16/22, 72.7%).
Three of them (n = 3/16, 18.8%) started a new sport activity/physical activity. However, 50% of the
physically active patients (n = 8/16, 50%) had to stop with one or more sports for medical reasons.
Regarding the subjective evolution of their physical wellbeing over the past five years, only three
patients (n = 3/22, 13.6%) reported an enhancement, whereas four patients (n = 4/22, 18.2%)
reported a steady state and 15 (n = 15/22, 86.2%) a decline in health. Likewise, the majority of the
patients reported to feel more restricted in performing activities of daily living compared to five
years ago (n = 18/22, 81.8%).
Nearly all EDS-HT patients in this study reported taking medication (n = 20/22, 90.9%). About half of
the patients (n = 12/22, 54.5%) described an increase of medication intake over the past five years.
Fourteen participants (n = 14/22, 63.6%) underwent surgery during the follow-up period.
23
Muscle strength
All strength parameters are summarized in Table 7. The total muscle strength, measured with hand-
held dynamometry, of the 22 EDS-HT patients was significantly higher on T2 compared to T1
(p < 0.001). A significant increase in hip flexion as well as ankle dorsiflexion strength was seen
(p < 0.001). Concerning the other strength components (6MWT, 30s CRT, MIP and MEP), no
significant differences between the two testing moments were observed.
If groups were compared, a difference was seen in those having an “equal” or “decreased” score on
the 30s CRT. Patients in the “decreased” group more often reported to use a walking aid or to have
stopped their sports activities. Patients in the group with a “decreased” distance on the 6MWT more
often described their health status on the testing day as ‘poor’.
Table 9: Muscle strength
Muscle strength T1 T2 Paired-Samples T test
Shoulder abduction strength (N) 124.60 ± 31.47 124.53 ± 44.61 p = 0.991
Hip flexion strength (N) 160.98 ± 34.76 216.84 ± 52.63 p < 0.001** ↑
Ankle dorsiflexion strength (N) 161.75 ± 31.16 246.84 ± 80.36 p < 0.001** ↑
Knee extension strength (N) 291.29 ± 72.69 287.60 ± 108.67 p = 0.796
Grip strength (N) 72.85 ± 26.18 82.15 ± 26.12 p = 0.052
Total muscle strength (N) 806.61 ± 146.70 1159.81 ± 279.47 p < 0.001** ↑
6MWT (m) 353.94 ± 140.28 315.67 ± 128.15 p = 0.189
30s CRT (rep) 10.09 ± 3.39 9.00 ± 3.59 p = 0.168
MIP (cmH2O) 71.29 ± 27.80 72.90 ± 26.61 p = 0.728
MEP (cmH2O) 86.61 ± 27.17 90.76 ± 25.61 p = 0.278
Values are the mean ± SD; * p < 0.05; ** p < 0.001; ↑ significant increase; ↓ significant decrease
Pulmonary function
The values of the FVC, FEV1 and Tiffeneau Index did not show any significant differences between
the two testing moments (p = 0.420, p = 0.878, p = 0.163). On the other hand, a significant decrease
was found in the PEF of T2 (mean: 333.41 ± 79.17 l/min) compared to T1 (mean: 365.23 ± 82.11
l/min) (p = 0.019). No association was found between patients labeled as “decreased”, “equal” or
“improved” for all these parameters and items of the follow-up questionnaire.
24
Aerobic capacity
The SRT and the 6MWT were used to evaluate the aerobic capacity of the EDS-HT patients. No
significant differences were seen between the two testing moments, except for the maximum
wattage on the SRT (p = 0.042). The mean wattage was 188.89 ± 60.94 at T1, whereas it was 214.17 ±
55.68 at T2.
A positive evolution of the subjective health status was more often reported by patients labeled in
the “improved” group compared to the “equal” group. Furthermore, patients who did have to stop
their physical activity for medical reasons during the past five years, had an “equal” or “decreased”
maximum wattage on the SRT compared to five years ago. On the other hand, women who did not
have to stop their physical activity are all classified in the “improved” or “equal” group.
Questionnaires
The results of the questionnaires are summarized in Table 9. A significant increase in the score of the
HAQ was seen, indicating that the patients experienced more difficulties in the activities of daily
living. Likewise, a significant decrease in the score of the SF-36, subscale physical functioning was
noticed. In other words, the participants perceived more limitations in physical functioning than five
years ago.
Table 10: Results questionnaires
T1 T2 Paired-Samples T test
HAQ, total 11.09 ± 4.32 18.27 ± 10.82 p = 0.002* ↑
HAQ, disability index 1.36 ± 0.56 2.28 ± 1.35 p = 0.001* ↑
SF-36, social functioning 6.09 ± 1.85 6.23 ± 2.29 p = 0.797
SF-36, physical functioning 20.18 ± 3.85 11.91 ± 2.81 p < 0.001** ↓
CIS20, subscale fatigue 43.17 ± 9.04 40.06 ± 7.94 p = 0.094
Values are the mean ± SD; * p < 0,05; ** p < 0,001; ↑ significant increase ; ↓ significant decrease
The influence of other possible confounders on the various parameters were evaluated. Poor or no
significant correlations could be found (data not shown).
25
Discussion
Summary of the results
To our knowledge, this follow-up study was the first to investigate the evolution of the physical
fitness in patients suffering from EDS-HT. The main objective was to provide insight into the
evolution of the different parameters of physical fitness, subdivided into three categories; muscle
strength items, aerobic capacity items and pulmonary function items. The results of the present
study show a significantly increased total muscle strength, and specifically a significant increase in
hip flexion strength and ankle dorsiflexion strength at T2 compared to T1. Furthermore, a
significantly increased maximum wattage on the SRT was noted. In the pulmonary function tests,
only significantly reduced PEF values were found.
Muscle strength
In contradiction to our expectations, total muscle strength was improved during the past five years.
To date, no studies are published to support this positive evolution. In cross-sectional studies,
Rombaut et al. and Scheper et al. showed significantly reduced muscle strength in EDS-HT patients
compared to healthy controls [13, 15]. Although our findings were unexpected, this may be
explained by several factors.
First, 77.3% of the patients reported to visit a physiotherapist at least once a week. Only one of them
enrolled in the physiotherapy program during the follow-up period. It is feasible that visiting a
physiotherapist on a regular basis may be appropriate to improve muscle strength in EDS-HT
patients. To support this hypothesis, significantly higher muscle strength as well as muscle strength
endurance in EDS-HT and JHS patients have been shown after an exercise program [38, 39]. This is in
accordance to the findings of Rombaut et al., where 63.4% of the participants noted a positive effect
of the physiotherapeutic treatment they received [40]. To date, very little has been reported about
the physiotherapy management of EDS-HT and the lack of evidence-based treatment approaches for
EDS-HT is a recognized concern. Rombaut et al. advised that physical therapy in adults with JHS/EDS-
HT should focus on symptomatic treatment of acute complaints (pain) and functional exercise
therapy with a focus on core and joint stability training. Furthermore, education about activity
management and chronic pain and joint protection can be useful [41].
Second, the improvement in muscle strength can possibly be explained by the positive relationship
between fatigue severity and muscle weakness in EDS patients [14]. The current study showed a
suggestive decrease of the CIS20 fatigue score. Thus, it is likely that the patients feel less fatigued
than five years ago, which may lead to an increased muscle strength. However, the mean CIS20
fatigue score on T2 still indicated severe fatigue (score ≥ 35) [42].
26
Furthermore, a suggestive but not statistically significant decrease in the score on the 6MWT as well
as in the score on the 30s CRT was noted at T2 compared to T1. In line, the cross-sectional study of
Rombaut et al. showed a significantly impaired balance, decreased walking speed, shorter step
length and stride length in the EDS-HT group compared to healthy controls [43]. Scheper et al.
confirmed these results. A significant lower score on the 30s CRT and 6MWT was found in EDS-HT
patients compared to healthy controls [13]. These findings may also be due to the fact that 45.5% of
patients have used a walking aid during the past five years.
Aerobic capacity
In the current study, a significant increase in maximum wattage on the SRT was found, supposing an
improved aerobic capacity. Garcia-Hermoso et al. suggested that there may be a link between the
aerobic capacity and the ability to perform activities of daily living [44]. For example, an
improvement in functional aerobic capacity in fibromyalgia patients led to favors in the capability to
carry out their tasks of daily living [45]. Our results on the SRT are in contradiction to the answers on
the follow-up questionnaire, where the majority of the patients had the perception to be more
restricted in performing activities of daily living. These subjective reports are in line with the
significant decrease in physical functioning (SF-36) and significant increase in physical impairment
(HAQ). Several authors confirmed the functional impairment in EDS patients [13, 46, 47].
Nevertheless, Bathen et al. showed that training can improve the ability to perform activities of daily
living [38].
It is feasible that the improvement of the maximum wattage on the SRT was the result of the
continuously received physiotherapy treatment as well as the performed sports activities. More than
50% of the patients reported to have regularly participated in one or more sports during the past five
years. Bicycling and walking are most frequently mentioned. These findings can be reflected in the
association between having to stop a physical activity for medical reasons during the past five years
and the maximum wattage on the SRT in the current study: Women who did not have to stop their
physical activity, had an improved or equal result on the SRT. Nevertheless, the habitual physical
activity level patients with EDS is lower compared to healthy control subjects [9].
Pulmonary function
In the pulmonary function tests, only significantly reduced PEF values were seen. The significant
increase in body weight, BMI and body fat percentage in EDS-HT patients during the follow-up study,
may play a role in this decrease. Al Ghobain et al. showed significantly lower results on spirometry
tests regarding the PEF in obese subjects in comparison to non-obese subjects [48]. These findings
27
can be explained by the increased total respiratory resistance and airway resistance in obese patients
[49].
Despite the decrease in PEF values, no significant differences in MEP values were noted. This can be
explained by the fact that the PEF is determined by the MEP in healthy subject. Nevertheless, in
patients with airways obstruction or increased airway resistance, maximum effort vital capacity
measurements will not result in maximum peak expiratory flow. Due to an airways collapse, a
significant drop in flow at a given volume will be noticed when alveolar pressure is raised above a
critical level [50]. Therefore, the PEF can decrease during the years because of the increasing BMI,
while the difference in MEP values will not be statistically significant.
Strengths and limitations
The present results must be viewed within the limitations of the study.
First, the evolution of the physical fitness parameters in the patient group could not be compared to
a healthy control group as intended at baseline. At T1, a healthy control group, individually matched
for gender, age and ethnicity participated. Unfortunately, they were not willing to participate at T2.
Nevertheless, the evolution of the patient group was the main focus of the study.
Second, the answers on the self-developed follow-up questionnaire were subjective reports and
were based on the patients’ memory of the past five years. Consequently, the results have to be
interpreted with some caution. A third limitation is the fact that relatively simple statistical tests
were performed because of the limited timeframe. Instead of the T tests and correlation tests, the
use of ‘Mixed Models’ would have been superior.
Despite these limitations, it should be highlighted that this is the first follow-up study in patients with
EDS-HT. The follow-up study was completed by 22 out of 26 patients, with a dropout rate of only
15.6%. This is a considerable sample size for the population, as EDS is a rare condition. In addition,
every patient was officially diagnosed at the Center for Medical Genetics and was re-evaluated for
new diagnostic criteria. Furthermore, the study consisted of standardized questionnaires and
standardized muscle strength, aerobic and pulmonary measures.
Future research
In the light of our findings, further research on the physical fitness level of patients suffering from
EDS-HT seems to be indicated over a longer period. The physical activity, as a confounding factor for
physical fitness, could be assessed more accurately using an accelerometer. Additionally, a case
control study may be more appropriate to observe the differences in the evolution of physical fitness
of EDS-HT patients in comparison to healthy controls.
28
Conclusion This study revealed an increase in total muscle strength and maximum wattage on the SRT in
patients suffering from EDS-HT over a five-year follow-up. These improvements might be the result
of the habitually performed physical activity and the regularly received sessions of physiotherapy by
the majority of the patients. By contrast, the results of spirometry demonstrate reduced PEF values.
The increased BMI may play a role in this decrease. Overall, no univocal consensus concerning the
physical fitness of EDS-HT patients could be shown. Further research on the physical fitness level of
patients suffering from EDS-HT seems to be indicated over a longer period.
29
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33
Abstract in lekentaal
Achtergrond: Het Ehlers-Danlos Syndroom (EDS) is een erfelijke bindweefselaandoening, met het
hypermobiele type (EDS-HT) als meest voorkomende vorm. Bindweefsel zorgt voor de stevigheid van
weefsels in het lichaam. Doordat de vorming hiervan verstoord is, ontwikkelen deze patiënten tal van
spier- en gewrichtsklachten.
Doelstelling: Het doel van deze studie was om de evolutie van de fysieke fitheid in kaart te brengen
bij deze patiëntengroep.
Methode: Er werden 22 vrouwen, gediagnosticeerd met EDS-HT, getest op twee momenten met een
tussenperiode van vijf jaar (2012-2017). Verschillende vragenlijsten en fysieke testen werden
afgenomen, waaronder een maximale spierkrachttest, een longfunctietest en een fietsproef.
Resultaten: Een opvallende toename van de kracht van de heupbuigers, de voetheffers en de totale
spierkracht werd gevonden. De maximale volumestroom bij een geforceerde uitademing was
opvallend gedaald in 2017 ten opzichte van 2012. Tot slot presteerden de patiënten beter op de
fietsproef tijdens het tweede testmoment.
Conclusie: Er werden mogelijke verklaringen gezocht voor deze veranderingen. Zo lijkt het volgen van
kinesitherapie en regelmatig sporten belangrijk te zijn voor deze patiënten. Verder onderzoek over
een langere periode is echter vereist om een eenduidige conclusie te kunnen vormen.
Bewijs van indiening bij het ethisch comité