LIHS Mini Master Class

Transcription

1 Alexandru Nicusor Matei 2013 CC BY-NC-ND 2.0 Measurement and valuation of health using QALYS John O Dwyer Academic Unit of Health Economics John O Dwyer University of Leeds This work is made available for reuse under the terms of the Creative Commons Attribution-NonCommercial- ShareAlike 4.0 International Licence.

2 One IVF course = 3,300 (2010/11 prices) One-half of a cochlear implant Nine cataract removals One heart bypass operation 300 vaccinations for Measles, Mumps and Rubella Three-quarters of a school teaching assistant for a year 5000 school dinners 1/400 of a Challenger 2 military tank (Morris, Devlin, Parkin & Spencer 2012)

3 Cost-effectiveness How do we compare across technologies? What is a unit of benefit worth? Uni-dimensional outcomes only address issues of technical efficiency Are these the only important outcomes?

4 Unit of benefit What is a unit of benefit worth? Outcome 1 Flu injection for the prevention of flu 374 per case of flu avoided Outcome 2 Inhalers for asthma 100 per symptom free week

5 How to measure QoL? 1. Visual Analogue Scale (VAS) Standard Gamble Time Trade Off (TTO) Point of indifference 4. Generic multi-attribute utility scales

6 Generic multi-attribute utility scales Two components a classification system defines health states a set of values for those health states Principal instruments EQ-5D.3 level & 5 level (NEW!!!) Health Utility Index (HUI) SF-6D (derived from SF-36) These instruments consist of a general health state descriptive system and an algorithm converting each health state into a utility value.

7 EQ-5D Levels of perceived problems are coded as follows: Level 1 is coded as a 1 Level 2 is coded as a 2 Level 3 is coded as a 3 NB: There should be only one response for each dimension. This health state = Utility = EQ-5D is a trade mark of the EuroQol Group.

8 EQ-5D This defines health more narrowly than general well-being but more widely than presence or absence of a physical condition It takes in three key dimensions: physical, mental and social; in line with the WHO definition But the dimensions in these sort of descriptive systems refer to attributes of health states only to the quality of health We also need to consider the duration or quantity of life Any meaningful metric of health should capture both A typical life span is shown on the following slide

9 Health Health span can be illustrated in a quantity/quality space 1 Dead Health 0 Time

10 Health Thus health span is a stream of health in which HRQoL is experienced in each time unit Each life year is weighted by HRQoL (ranging from 0 representing dead to 1 representing best imaginable health/full health) At an individual level health gains are measured in terms of expected increase in quality and quantity of life and typically expressed as quality adjusted life years (QALYs) At population level the more people that receive individual health gains the higher total gains to society

11 QALYs

12 Each treatment is considered on a case-bycase basis. Generally, however, if a treatment costs more than 20,000-30,000 per QALY, then it would not be considered cost effective. -NICE 2010

13 Calculation (NICE example) Patient x has a serious, life-threatening condition. If he continues receiving standard treatment he will live for 1 year and his quality of life will be 0.4 (0 or below = worst possible health, 1= best possible health) If he receives the new drug he will live for 1 year 3 months (1.25 years), with a quality of life of 0.6.

14 Calculation The new treatment is compared with standard care in terms of the QALYs gained: Standard treatment: 1 (year's extra life) x 0.4 = 0.4 QALY New treatment: 1.25 (1 year, 3 months extra life) x 0.6 = 0.75 QALY Therefore, the new treatment leads to 0.35 additional QALYs (that is: QALY = 0.35 QALYs).

15 Calculation The cost of the new drug is assumed to be 10,000, standard treatment costs The difference in treatment costs ( 7000) is divided by the QALYs gained (0.35) to calculate the cost per QALY. So the new treatment would cost 20,000 per QALY. (i.e. 7000/.35)

16 Some Criticisms Whose preferences should be used? Self-reporting issue for some patients. Are their preferences adequately reflected so correct quality of life can be determined?...measurement problem Is the threshold appropriate?

17 Key Points A measure of the state of health of a person or group in which the benefits, in terms of length of life, are adjusted to reflect the quality of life. One QALY is equal to 1 year of life in perfect health. QALYs are calculated by estimating the years of life remaining for a patient following a particular treatment or intervention and weighting each year with a quality of life score (on a zero to 1 scale).

18 Further Information Key references Morris, S., Devlin, N., Parkin, D Economic Analysis in Health Care. John Wiley & Sons: Chichester. Chapter 10. Brazier, J., Ratcliffe, J., Salomon, J., Tsuchiya, A. (2007), Measuring and Valuing Health Benefits for Economic Evaluation, Oxford University Press Drummond, M.F., Sculpher, M.J., Torrance, G.W. O Brien, B., Stoddart, G.L Methods for the Economic Evaluation of Health Care Programmes. 3 rd ed. Oxford University Press: Oxford. Chapter 5, section 5.4 and Chapter 6 Olsen, J.A., Principles in Health Economics and Policy. Oxford University Press: Oxford. Chapter 13 (on the QALY concept) Carr-Hill, R., and Morris, J., Current practice in obtaining Q in QALYs: a cautionary note. British Medical Journal, 303,