Jung-Der Wang, M.D., Sc. D. National Taiwan University College of Public Health

1. Comparative health risk/impact assessment for occupational and environmental health: Integration of survival and quality of life Jung-Der Wang, M.D., Sc. D. National Taiwan University College of Public Health National Taiwan University Hospital

2. OUTLINES • Introducing the needs and concepts of survival, quality of life (QOL), and quality-adjusted survival as outcome indicators with QALY (quality-adjusted life year) and/or life year as a common unit for risk/impact and cost-effectiveness assessment • Quantification of contribution from preventive services and examples • Integration with medical cost from the NHI

3. Determinants of RISK: (BS8800) LIKELIHOOD OF EVENT (Incidence rate or probability) X CONSEQUENCE OF EVENT (loss of utility due to the event) (survival integrated with quality of life)

4. Environmental and Occupational Health Risk Assessment • For sustainable development, we always want to reduce health risk or replace toxic substances by a less toxic compound. But how do you compare nephrotoxicity with hepatotoxicity? • Different health events cannot be directly compared, unless quantified with the same unit in health

5. A common question raised: • Is there a common unit to measure both the survival and utility (or psychometry) of quality of life? • Live vs. Dead ---- counting the no. of lives saved • More delicate measures: --Length of survival S(t) or S(ti|xi) --Quality of life Qol(ti|xi) • Can we measure S(ti|xi) or Qol(ti|xi)? • Can we develop a method to combine both? • (Can we quantify the cost paid by the NHI? )

7. Concepts, Ethics, Measurementand Applications Edited by Christopher J.L. Murray, Joshua A. Salomon, Colin D. Mathers and Alan D. Lopez Summary Measures of Population HealthWHO 2002 http://www.who.int/publications/smph/en/

8. Global and Regional Burden of Disease Attributable to Selected Major Risk Factors Edited by Majid Ezzati, Alan D. Lopez, Anthony Rodgers and Christopher J.L. Murray Comparative Quantification of Health Risks- WHO2004 http://www.who.int/publications/cra/en/

9. Treatments for Existing Conditions(NEJM2008;358:661-3) • Cognitive-behavioral family intervention for patients with Alzheimer’s disease Cost-saving • Cochlear implants in profoundly deaf children Cost-saving • Combination antiretroviral therapy for HIV-infected patients $29,000/QALY • Liver transplantation in patients with primary sclerosing cholangitis $41,000/QALY • Implantation of cardioverter defibrillators in appropriate populations, compared with medical management alone $52,000/QALY

10. Preventive Measures (NEJM2008;358:661-3) • Haemophilus influenzae type b vaccination of toddlers Cost-saving • One-time colonoscopy screening for colorectal cancer in men 60-64yr of age Cost-saving • Newborn screening for medium-chain acyl-coenzyme A dehydrogenase deficiency $160/QALY • High-intensity smoking-relapse prevention program, as compared with a low-intensity program $190/QALY • Intensive tobacco use prevention program for 7th and 8th graders $23,000/QALY

12. Estimated survival function, mean QOL and quality adjusted survival curve; The area under the QAS curve is the expected quality adjusted survival time (Hwang JS, et al Statistics in Medicine 1996;15:93-102)

13. Notation of a typical life table with added columns of QOL (quality of life) and QAST (quality adjusted survival time)

14. A more general model: • xi:determinant(s) of S(survival) and U(utility) functions e.g. head injury, stroke,….., etc. • Quality adjusted survival Qol(t| xi): quality of life function (Wang JD. Basic principles and practical applications in epidemiological research. 2002)

15. ILLUSTRATIVE EXAMPLES: • How much utility of health (in QALY) does it cost for a case of end stage renal disease or liver cancer? • --- Survival curve • --- Quality of life estimation --- General population of Taiwan in 2000 as the reference population assuming QOL=1

16. quality of life survival curve quality-adjusted survival

17. 17.5 QALY

18. Pit dug for washing underground soil and water

19. *MCLG: Maximum Contaminant Level Goal †MCL: Maximum Contaminant Level

20. Determinants of RISK: (BS8800) LIKELIHOOD OF EVENT (Incidence rate or probability) X CONSEQUENCE OF EVENT (loss of utility due to the event) (survival integrated with quality of life)

21. Cancer risks based on RME (reasonable maximal exposure) and cancer slopes Vinyl chloride 8.4 x 10-6 Tetrachloroethylene 1.9 x 10-4 Trichloroethylene 1.4 x 10-4

25. Examples helmet law for motor cycle riders

26. Comparison of QALY loss from head injuries occurred in motorcyclists with and without wearing a helmet(Lee HY et al. Am J Public Health 2009 accepted)

27. Head Injury Registry in Taiwan 3328 hospitalized patients with motorcycle-related head injuries 22 major hospitals 2001~2007

28. Survival QOL QALE 1 0 50-year extrapolation Follow-up limit

30. EuroQol-5D questionnaire Usual activities 0~1 utility score Mobility Self-care Anxiety/ depression Pain/ discomfort

31. Telephone interviewed: 190 cases Good outcome Bad outcome

33. good outcome: 35.3 QALYs bad outcome: 7.6 QALYs Proportion to weight 12%7.6 34%x7.6 88% 35.3 66%x35.3 Non-helmeted riders QALE: 25.9 QALYs Loss: 10.7 QALYS Helmeted riders QALE: 31.7 QALYs Loss: 5.8 QALYs

34. In addition to reduced incidence rate, Simple use of a helmet could save 5 QALYs in a motorcycle-related head injury

35. Health risk assessment for occupational lead exposure policy • 649 female lead workers • Exposure assessment: blood lead • Hazard identification: lead can impair IQ of offspring of lead workers • Dose response: < 30 ug/dl reversible > 30 ug/dl irreversible . Risk characterization: estimation of QALY loss due to different policy Chuang HY, et al. J Toxicol Environ Health 2005 ;68:1485-96

36. Table 1 Numbers of prospective offspring from female lead workers in 1991. (ASFR - age specific fertility rate)

37. Table 1 (Continued)

38. Table 3 Estimated utility loss in QALY from 2 different occupational health policies

39. Cost of illness approach: • Human capital left over for determinant xi WA(t| xi): work ability function • Direct medical cost of determinant xiCost(t| xi): medical cost function

41. Monthly cost (NT$) for hemodialysis

42. Lifetime cost (NT$) for hemodialysis

43. HOW MUCH DOES IT COST FOR A UNIT OF SCORE-TIME? • Through questioning 157 patients with disability caused by occupational injury under contingent valuation method or stated preference, we found that people are willing to pay US$ 65.1-69.6 for a pain-killer pill that can remove pain for 24 hours. Ho JJ, et al. et al. (monetary value of score time) Accident Analysis & Prevention 2005;37:537-48 • The WTP money for removing a longer duration of pain is even bigger

44. Conclusion: for risk/impact assessment in health and medicine • The QALY or life year gained or loss can be estimated for comparative risk/impact assessment of occupational and environmental health • Lifetime medical cost and human capital cost saved by prevention can also be quantified and compared with all other health care services

45. Hwang JS, Tsauo JY, Wang JD. (theory of QAS) Stat Med 1996;15:93-102 Hwang JS, Wang JD. (QAS extrapolation to lifetime) Stat Med 1999;18:1627-40 Tsauo JY, et al. (Utility of enforcement of helmet law) Accident Anal Prev 1999;31:253-63 Yao KP, et al. (WHOQOL-BREF Taiwan version) J Formos Med Assoc 2002;101:342-51 Lee LJH, et al. (Risk assessment for water pollution) J Toxicol Environ Health 2002;65:219-35 Hwang JS, Wang JD (extended to psychometry) Quality Life Res 2004; 13:1-10 Hsu J, et al. (bone marrow transplantation for leukemia) Qual Life Res 2003 ;12:503-517 Chuang HY, et al. (occupational health policy for lead) J Toxicol Environ Health 2005; 68:1485-96. Ho JJ, et al. (monetary value of score time) Accident Anal Prev 2005;37:537-48. Ho JJ, et al. (survival of occupational disability) Scand J Work Environ Health 2006; 32(2):91-98. Ho WL, et al. (survival and cost of thalassemia) Bone Marrow Transplant 2006; 37(6):569-574. Ho JJ, et al. Estimation of reduced life expectancy. Accident Anal Prev 2006; 38:961-968. Fang CT et al. (Life expectancy of patients with HIV/AIDS). Quarterly J Med 2007; 100:97-105. Fang CT et al. (Cost-effectiveness for HAART policy) J Formos Med Assoc 2007; 106(8):631–640 Chu PC et al. (Lifetime financial burden to the National Health Insurance for 17 different cancer in Taiwan) J Formos Med Assoc 2008; 107:54-63 Chu PC et al. (Life expectancy and loss of life expectancy for major cancer in Taiwan) Value in Health 2008; 7:1102-1109 Chang CY et al (Quality of life in obese patients) Obesity Surg 2008; DOI 10.1007/s11695-008-9513-z Lee HY, et al. How many quality-adjusted life years can a helmet save for a motorcyclist when head injury occurs? Am J Public Health 2009 (accepted)

46. THANK YOU FOR YOUR ATTENTION

47. Life-time utility (Economist) 經濟學家：終生預期效用 survival function人命(存活函數)utility function --HRQL(健康相關生活品質) --working ability, wages, medical costs 工作能力、薪資、醫療費用 • Quality-adjusted life expectancy or healthy life expectancy (生活品質調整後預期壽命)