The 1st National TB Prevalence Survey Nigeria 2012

Preliminary/Final Results

29th April 2013

Dr. Joshua Obasanya

NTP Manager/ PI National TB Prevalence Survey

2 |

Background

Indicator (2011)

Population size 162.5million

GNI per capita (Atlas method) 2011($1,280)

Estimated TB Burden (2011) Number Rate

Cases (all forms) 190,000 118/100,000 (2011)

Mortality 17 per 100,000 (2011)

TB cases with HIV 30% (2011) N/A

Case notifications 60 per 100,000

Treatment success 85.5%

Methodology

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Sampling design

Sample size: 49,000 eligible adults (15 yrs and above)

Number of clusters: 70

A multi-stage sampling method was used – Stratifying the country into 6 geopolitical zone – Population based simple random sampling

Target clusters people

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Selection criteria and health seeking behaviour

Inclusion criteria – All permanent residents in the household – Non-permanent residents who have spent at least 2 weeks in the household

by the survey day – At least 15 years of age – Those who have provided informed consent

Screening Positive – Two sputum samples (1 spot and 1 morning) will be obtained from persons

reporting a cough greater than or equal to 2 weeks in duration or chest X-ray examination that show any radiographic abnormalities.

Health seeking behaviour (2 questions) – What did you do about your symptoms? (Not recognised as illness, ignored, self

treatment, consulted health service, others ) – If response to question above is “consulted health service”, Where did you first

seek care? (HC/PHC, Private Hosp., Traditional healer, Chemist, GH, Teaching Hosp., Mission Hosp., others )

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Laboratory methods

Smear: – Direct in 2 Labs and Concentrated in 1 Lab – Ziehl-Neelsen staining

Culture media: – Löwenstein–Jensen (LJ) – For positive growths, identification for MTBC was done

Other: – 3 Refence Labs were used ( Zankli, NTBLTC Zaria and NIMR) – Use of GeneXpert MTB/RIF for few samples with inconsistent results

( specifically for Zaria processed samples) e.g. 1 smear pos sample, cult-ve, X-ray TB suggestive

Main Challenges

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Main challenges of survey implementation

Case review style exercises were consistently carried out with support from WHO Geneva & CDC Atlanta to improve the quality of data generated

S/No Challenge Action

1 On-going security challenges in Kano, Kaduna, Yobe and Borno states

2 states (Yobe & Borno) were excluded. To compensate, 3 clusters with similar characteristics were chosen for replacement

2 Low participation due to Rain/Farming/Fasting period

suspension of survey field activities for 5 weeks (from end of July – August 26th 2012)

3 Absenteeism experienced in urban settings

Field teams worked till late hours while re-mobilization was done through community & religious leaders

4 Backlog and increased workload for Zaria Laboratory ( because 2 clusters ran concurrently)

Zankli Lab was engaged to support in processing some of samples already delivered to Zaria

5 Gaps between field sample collection and lab reporting and between lab reporting and feedback to participants for enrolment of care. These was coupled with sputum transport challenges

• Labs were visited routinely every 2 weeks to retrieve results that were delayed •Survey central team developed and regularly updated the list of detected cases on weekly basis . Feedbacks of results were sent to patients through State Program officers and Zonal survey coordinators •Feedback on enrolment of detected cases received during review meetings •Change from public transport to courier transport

6 Delay in Central Xray reading and entry into data base

• 5 Additional data clerks were identified to support the central data manager with entry of central X-ray and Lab results .

7 Delayed Procurement (especially lab equipments & consumables availability and specification) which resulted in late take-off of the survey

•The NTP had to intervene

RESULTS

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Participants

• 113,057 Total census

• 77,596 (68.6%) • 34,962 (31%) children • 499 (0.44%) non-residents

Eligible to participate

• 43,439 (56%) Participants

Ineligible individuals

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Eligibility by age group and sex

90.0

95.0

100.0

15 to 24 25 to 34 35 to 44 45 to 54 55 to 64 65+

Perc

enta

ge e

ligib

le (%

)

Age group (years)

Eligibility by age group and gender

Male

Female

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Participation by age group and sex

40.0

50.0

60.0

70.0

80.0

90.0

100.0

15 to 24 25 to 34 35 to 44 45 to 54 55 to 64 65+

Part

icip

atio

n ra

te(%

)

Age Group (Years)

Participation by age group and sex

Male

Female

Overall participation rate: 56%

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Participation by cluster

0

10

20

30

40

50

60

70

80

90

100

42 56 68 43 54 69 11 70 41 55 44 46 67 47 66 45 14 38 57 49 48 64 39 65 40 50 63 2 51 8 9 13 33 62 1 53 35 3 34 4 61 52 7 18 5 10 6 36 12 60

Part

icip

atio

n ra

te (%

)

Cluster number

Participation rate by cluster (chronological order)

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Screening and laboratory investigations

• 43,439 Total screened

• 4,429 (10%) Symptom positive

• 2,016 (45.5%) CXR positive

• 724 (16.4%) Both symptom and CXR positive

• 1,670 (38.1%) Screened positive

• 4,283 (at least one specimen) Total specimens obtained

• 4,283 Number of participants with lab results

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Results of TB Prevalence : Age ≥ 15years*

1) Smear Positive MTB case (N=107):

Correlation coefficient of between-cluster variation (k): 0.82 Design effect: 2.56

2) Bacteriologically Confirmed MTB (N=148):

Correlation coefficient of between-cluster variation (k): 0.78 Design effect: 2.48

255 per 100,000 (95%CI 178-333)

353 per 100,000 (95%CI 264-442)

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Prevalence of culture confirmed MTB cases by age:

0

200

400

600

800

1000

1200

1400

15-24 25-34 35-44 45-54 55-64 65+

Prev

alen

ce p

er 1

00,0

00

Age group (years)

Prevalence of smear-positive and bacteriologically-confirmed TB by age group

Smear positive culture positive

Bacteriologically positive

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Prevalence of culture confirmed smear positive TB by age and sex:

Age Group (Years)

0

500

1000

1500

2000

2500

3000

15-24 25-34 35-44 45-54 55-64 65+

Prev

alen

ce (p

er 1

00,0

00)

Age group (Years)

Prevalence of bacteriologically-confirmed TB by sex and age group

Male

Female

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Confirmed MTB survey cases: Symptoms and CXR screening results

Screening method Smear positive MTB survey cases

N=107

Bacteriologically confirmed MTB survey cases

N=148

Total number of survey cases

Percentage of all survey cases

Total number of survey cases

Percentage of all survey cases

Symptom positive only 13 12% 17 11.5% CXR positive only 27 25% 54 36.5% Symptom and CXR positive 67 63% 77 52%

• What proportion of MTB survey cases were smear negative? 27.7% • What proportion of MTB survey cases were detected by CXR? 36.5% • What proportion of MTB survey cases were detected by symptoms? 11.5% • What proportion of MTB survey cases would have been detected by the current screening strategy in your country? 11.5%

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Comparison of Prevalence to Notification (2011)

0

1

2

3

4

5

6

7

8

National(15+)

Male(15+)

Female(15+)

15 to 24yrs

25 to 34yrs

35 to 44yrs

45 to 54yrs

55 to 64yrs

65+ yrs

Prev

alen

ce to

Not

ifica

tion

ratio

Categories

Prevalence to Notification Rate ratios; total, by sex, and age group Comparison of notification (2011) to prevalence (smear-positive)

Lessons Learnt

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Major lessons and implications to the NTP

What are the main lessons derived from the survey results? – Data management is the bedrock of a successful survey (a simplified and

user friendly database is crucial). – Low participation rate (56%) – 75% of smear positive study cases are symptomatic (consistent with 2013

Prog. Rev. findings) – Participation rate higher in females and older individuals ( health seeking

behaviour among men still a challenge) – Survey findings (prevalence) seems to be higher than current WHO

estimates (further analysis required) What action is recommended based on the findings?

– Modern and strategic approaches to creating awareness within the community is pertinent

– Strategic expansion of more microscopy centers than DOTS centers to increase access to diagnosis is needed

– Stakeholders meeting to brainstorm on strategies for increasing case detection

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Acknowledgements

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Ded

icat

ion,

mut

ual

resp

onsi

bilit

y an

d a

soun

d da

ta m

anag

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!

Supplementary slides

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Laboratory results

• X,XXX (spot) X,XXX (morning) Total specimens obtained

• XXX (X.X%) Any smear positive

• XXX (X.X%) Any culture MTB

• 75(51%) S+C+

• 41 (28%) S-C+

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Study cases

Smear positive MTB cases

Bacteriologically confirmed MTB cases

Total number of study cases 107

148

Definite case 75

39

Probable case 32

2

Possible case

30

Non-study cases 38

-

Number of cases that are smear positive

-

107

Definite cases: Probable cases: Possible cases: Non-study cases:

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Health seeking behaviour Analysis on-going

Indicator

Total number of TB survey cases

Number of TB survey cases who were not on treatment at the time of the interview

Number of TB survey cases who were symptomatic

Number of symptomatic TB survey cases not on treatment at the time of the interview

Number of TB cases detected by the survey who were already on treatment (Where did they seek care?)

Number of symptomatic TB cases not on treatment but who sought care (Where did they seek care?)

Number of TB survey cases that started on treatment after being detected by the survey

Slide Number 1Background�Slide Number 3Sampling designSelection criteria and health seeking behaviourLaboratory methodsSlide Number 7Main challenges of survey implementationSlide Number 9ParticipantsEligibility by age group and sex� Participation by age group and sex�Participation by cluster�Screening and laboratory investigationsResults of TB Prevalence : Age ≥ 15years*Prevalence of culture confirmed MTB cases by age:Prevalence of culture confirmed smear positive TB by age and sex: �Confirmed MTB survey cases: Symptoms and CXR screening results�Slide Number 19Slide Number 20Major lessons and implications to the NTPAcknowledgements�Slide Number 23Slide Number 24Laboratory resultsStudy cases�Health seeking behaviour�Analysis on-going