Patients’ preferences for preventive osteoporosis drug treatment

EW de Bekker-Grob

ML Essink-Bot

WJ Meerding

HAP Pols

BW Koes

EW Steyerberg

Dept. Public Health, Dept. Internal Medicine, and Dept. General Practice,

Erasmus MC Rotterdam, the Netherlands

e.debekker@erasmusmc.nl

BACKGROUND

Osteoporosis Risk factor for fractures (low bone mass)

75.000 osteoporotic fractures annually in NL

15.000 hip fractures

60.000 other fractures

Age risk factor

Preventive medication (bisphosphonates)

Study Active case finding important to identify patients who benefit from

preventive drug treatment.

Are subjects willing to take preventive drug treatment?

AIM

1. To elicit relative weight that patients place on various aspects of

preventive osteoporosis drug treatment

2. To investigate whether high risk patients had other preferences

than low risk patients.

METHODS I

Respondents

Women aged over 60 years

Identified by case finding in 34 GP-practices in NL

Overrepresentation high risk (10-yrs risk hip # > 6%)

DCE

Respondents choose between different options described by drug

treatment attributes at different levels

METHODS II

Background information DCE

Survey method

Good and services can be described by their characteristics

(attributes)

Used to estimate:

Whether attribute is important

Relative importance of attributes

Trade-off between attributes

Willingness to pay (monetary measure of benefit)

ATTRIBUTES and ATTRIBUTE LEVELS

Attributes Attribute levels

Tablet once a month,Tablet once a week,Injection every four months,Injection once a month5, 10, 25, 50

of hip fracture)Yes, No1, 2, 5, 100, 120, 240, 720Total out of pocket costs (€)

Way of drug administration

Effectiveness (% risk reduction

Side effects (nausea)Total treatment duration (yrs)

CHOICE SETS

Fractional factorial design (main effects only design)

16 drug profiles

Folder-over technique (01, 12, etc) for minimal overlap

Treatment A Treatment B No treatment

Way of drug administration

Tablet once a week

Injection by GP every 4 months

Not applicable

10-years risk reduction of a hip fracture

10% 25% 0%

Nausea (during two hours after use)

Yes No No

Total treatment duration 2 years 5 years 0 years Total cost to you € 0 € 120 € 0

Which treatment 0 Treatment A 0 Treatment B 0 No treatment do you prefer?

ANALYSES

Patient preferences conditional logit regression

V = β0 + β1TABLETweekly + β2INJECTIONfourmonths +

β3INJECTIONmonthly + β4EFFTIVENSS + β5NAUSEA + β6TIME +

β7COST

Time and monetary trade-offs ratios of coefficients

High vs low risk conditional logit regression with interaction

RESULTS: RESPONDENTSAll

patients (%)

LR patients

(%)

HR patients

(%)120 60 60

Age <0.001 *60-64 28 21 7

64-69 18 11 7

70-74 20 17 3

75-79 28 10 28

80 and older 26 1 25

Household <0.001 *single 53 17 36

with partner 67 43 24

Eductional level 0.215Low 63 31 32

Intermediate 46 26 20

High 11 3 8a significant difference between low and high fracture risk patient groups

* significant at the 5% level

P-valuea

Group

RESULTS: CONDITIONAL LOGIT REGRESSION

Beta coefficient

p Value

Constant (drug treatment) 1.23 <0.001* 0.81 1.66Drug administration (base level

tablet once a month):tablet once a week -0.31 <0.001* -0.45 -0.17injection every four months -0.21 0.027* -0.41 -0.02injection once a month -0.44 <0.001* -0.64 -0.25

Effectiveness (10% risk reduction) 0.28 <0.001* 0.23 0.34Side effect nausea -1.10 <0.001* -1.30 -0.89Treatment duration (1 year) -0.04 <0.001* -0.06 -0.02Cost (€100) -0.15 <0.001* -0.18 -0.11* significant at the 5% level

Attribute 95% CI

Number of observations 5,589 (117 respondents x 16 choices x 3 options per choice, minus 27

missing values), Pseudo R2 = 0.1847, log pseudolikelihood = -1668.7

RESULTS: TRADE-OFFS

WTP for total

treatment (€)

Constant (no drug treatment) 32.7 847Drug administration (base level

tablet once a month):tablet once a week 8.2 212injection every four months 5.7 147injection once a month 11.7 304

Effectiveness 7.5 195Side effect nausea 29.0 752Treatment duration 26Cost 3.9

Attribute

Willingness to adhere to the

drug treatment longer (years)

RESULTS: EXAMPLE

Bisphosphonate

Weekly tablet

Nausea

Duration 5 years

Women prefer this drug treatment above no drug treatment,

if WTP is positive, thus

0 < €constant + €weekly tablet + €nausea + €time + €effectiveness

WTP = 847 – 212 – 752 – 5*26 + 20*X

Risk Reduction (%)

0 10 20 30 40

WT

P (

€)

-200

0

200

400

600

If risk reduction is larger than 12%, than out-of-pocket

payment becomes acceptable

LOW VS HIGH FRACTURE RISK PATIENTS

AttributeCoefficient of

low risk patients

Coefficient of high risk patients

p-value

Constant (drug treatment) 1.18 1.32 0.75Drug administration (base level

tablet once a month):

tablet once a week -0.36 -0.26 0.46injection every four months -0.13 -0.32 0.32injection once a month -0.45 -0.45 0.97

Effectiveness (10% risk reduction) 0.23 0.34 0.05 *Side effect nausea -1.05 -1.16 0.58Treatment duration (1 year) -0.03 -0.05 0.58Cost (€100) -0.20 -0.10 0.44*significant at the 5% level

Number of observations 5,589 (117 patients (i.e. 58 low-risk + 59 high-risk patients) x 16 choices x 3

options per choice, minus 27 missing values), Pseudo R2 = 0.190, log pseudolikelihood = -1659

CONCLUSIONS

1. Women exhibited a very positive attitude towards preventive

osteoporosis drug treatment

2. Important message for policy decision-making on introduction

of active osteoporosis case finding at large scale (in addition to

cost-effectiveness considerations)

3. This study demonstrates feasibility of DCE in older patients

We would like to thank the Netherlands Organization for Health Research and Development (ZonMw) for funding the research.