The valuation of disease-specific questionnaires for QALY analysis

1. The valuation of disease-specific questionnaires for QALY analysis • To rescue data in absence of an utility measure • Growth hormone deficiency in adults • To increase sensitivity • Benign Prostatic Hyperplasia (BPH)

2. Mapping Trying ‘to map’ disease characteristics on EQ-5D etc. Nord E. Cost-utility analysis of Melphalan plus Prednisone with or without Interferon Alfa-2b in newly diagnosed multiple myeloma. Pharmacoeconomics 1997;12:89-103. Can be done behind the desk Very quick… Very dirty… A low face validity…

3. Mapping DALY style

4. QoL-AGHDA • Quality of Life Adult Growth Hormone Deficiency Assessment • 25 yes/no items • Internet panel • N = 1075 • Both AGDHA and EQ-5D

5. From AGDHA to utilities (QALY) EQ-5D: 5 dimensions AGHDA: 25 dimensions Utility Algorithm Sum Score Regression Regression Utilities Total score

6. Regression Dutch AGHDA sum score on EQ-5D

7. EQ-5D-3L versus EQ-5D-5l

8. Cross walk

9. Validation

10. Calculation

11. The AGHDA has generic features… • AGHDA • I have to struggle to finish jobs • I feel a strong need to sleep during the day • I often feel lonely even when I am with other people • EQ-5D • I have some problems with performing my usual activities • I am moderate anxious or depressed • Correlation makes sense

12. But what if the measure has little generic features? • International Symptom Prostate Score (IPSS) • BPH • Enlargement of the prostate • Causes voiding problems in elderly men • Difficulties to pee • 7 questions: How often have you • had to push or strain to begin urination? • had a sensation of not emptying your bladder completely? • had to urinate again less than two hours after you finished urinating? • found you stopped and started again several times when you urinated? • you find it difficult to postpone urination? • had a weak urinary stream? • How many times did you most typically get up to urinate from the time you went to bed at night until the time you got up in the morning?

13. Does the EQ-5D make sense in BPH? • MOBILITY • I have no problems in walking about • I have some……. • I am confined to bed • SELF-CARE • I have no problems with self-care • I have some problems….. • I am unable… • USUAL ACTIVITIES • I have no problems with performing my usual activities • I have some problems… • I am unable…. • PAIN/DISCOMFORT • I have no pain or discomfort • I have moderate ….. • I have extreme…….. • ANXIETY/DEPRESSION • I am not anxious or depressed • I am moderately…….. • I am extremely….. Not sensitive for BPH

14. Can we convert the IPSS outcomes into utilities? Attribute TTO values to the IPSS health states Problem: IPSS has 279.936 health states 7 items, 6 answer levels = 6x6x6x6x6x6x6 = 279.936 health states Too many to value with TTO Reduce number of health states Reduce items Factor analysis Reduce answer levels Combine answer levels

15. Factor analysis on patients IPSS responses N = 1414 Two main factors Obstructive (alpha= 0.8018) Irritative (alpha= 0.7165) Confirmed in literature Factors divided in 3 levels Number of health states reduced to 33 = 9 Can be valued directly TTO General public, representative for gender/age (N=170) Reduce number of health states

16. Exercise • Value the 9 health states of the reduced IPSS • Tests feasibility: can it be done? • Compare values with earlier research • Test reliability: can we repeat the observation? • Scientific prove (observation is independent of examination) • Do different groups of people have different values

17. QALY weights for BPH

18. Comparing ISPOR 2003 with population

19. How to come to these values?

20. Treatment effect

21. No disease specific problems Healthy All disease specific complains Death Disease specific utilities are not on a generic scale • Generic top anchor • absence of any impairment • Specific top anchor • absence of specific impairment • Co morbidity might still be present

22. No disease specific problems Healthy All disease specific complains Death Disease specific utilities are a subscale of a generic scale • Rescaling necessary

23. Raw disease specific trade-off ten to overestimated gains • Value of life years “traded off” in TTO differently • Healthy subject: 1 life year is 1.0 QALY • Sick subject: 1 life year is 0.8 QALY • Life years of healthy persons are more worth than those of sick • Disutility is proportional • 20% trade off at 1.00: disutility = 0.20 • 20% trade off at 0.80: disutility = 0.16 • 20% trade off at 0.60: disutility = 0.12

24. Specific utilities should be corrected for average morbidity • Solution: multiplicative model • Multiply disease specific value with average value • Values have to be multiplied by average value for age group. • For instance in IPSS • male age 55-64: overall QoL utility: 0.81 • Most severe BPH: 0.87 • Male age 55-64 with most severe BPH: 0.81 x 0.87 = .7047 • Maximum gain reduces from • Raw score 1.00 - 0.87 = 0.13 • Adjust score 0.81 - 0.70 = 0.11 • 15 % reduction

25. Rue of thumb • Overestimated CE-ration by 15% using specific utilities • Proposed by Fryback & Lawrence, MDM 1997 • For not completely the same problem… • …for own health states, not imaginable health states

26. We validated the IPSS for the use in economic appraisal Now, IPSS has QALY-weights New and already published research can be converted into QALYs Advantage use specific QALYs measures High sensitive disease specific measures for QALY-analysis Rescuing data Disadvantages Not directly compatible with generic utilities ± 15 % correction needed in disease specific Conclusion