OBJECTIVE

1. After extrapolation to 50 years, the HG for an average case of pneumoconiosis was 53.3%. The relative bias for the Monte Carlo method was 7.1 % after 10 years of extrapolation, as summarized in Table 1. • CONCLUSION • The LE and QALE for patients with pneumoconiosis is found to be significantly shorter than that of the general population with the same sex and age, indicating health impact on society resulted from occupational pneumoconiosis. Actions must be taken to prevent such losses in the future through the development of technology for proactive prevention, exposure monitoring and control. Figure 1. Survival of patients with pneumoconiosis Health impact of occupational pneumoconiosis in Mongolia: Estimation of life expectancy, quality-adjusted life expectancy & their losses… OyunbilegSh1MD, MPH, Wang JD 1MD, ScD, Sumberzul N,MD, PhD 2, Chang YY 1, MPH1Institute of Occupational Medicine & Industrial Hygiene, College of Public Health, NTU; 2Health Science University of Mongolia Figure 2. QAS for patients with pneumoconiosis Quality adjusted survival OBJECTIVE To estimate the life expectancy (LE), expected years of life loss (EYLL), quality-adjusted life expectancy (QALE), loss of healthy life expectancy (LHLE) and health gap (HG) for patients with pneumoconiosis in Mongolia. METHODS AND MATERIALS The cohort was established on retrieving information from registered 21-year survival data of the National Research Center of Occupational Diseases, which were linked to the National Mortality Registry of Mongolia to obtain the survival function. We used the extrapolation method of LE. The average EYLL of patients with pneumoconiosis cohort was defined as the mean survival difference between an average patient & age-, gender-matched reference group simulated by Monte Carlo method from the life table of Mongolia in 1996. QALE based upon a follow-up period of 21 years and 50 years of extrapolation was calculated from summing up the life-long extrapolated QAS function. We adopted utility values for EQ-5D established by U.K. studies to determine the utility value of workers with pneumoconiosis. Estimation of the LHLE from developing the disease under study by subtracting the area under the QAS curve of pneumoconiosis from that of the age- & sex-matched reference group simulated from Monte-Carlo method. STATISTICAL ANALYSES MC-QAS statistical package and the standard error of the survival estimate was obtained through a bootstrap method. The statistical analysis was conducted by using the SAS 9.1.. To validate the method, we used follow-up data for the first 11 years and then extrapolate to 21 years through Monte Carlo method. The cohort data based on the Kaplan–Meier estimation method was calculated as the “gold standard”. The 1996 life-table of the general population of Mongolia was used and the relative bias for pneumoconiosis was computed. RESULTS From the established cohort, 432 eligible patients with occupational pneumoconiosis were included in the population and 68.3% of them are still alive. The mean age was 54.3±9.8 years. The average working duration was 15.8 ± 6.1 years. The censored rate for the survival analysis was 31.7% by the end of the 21-year follow-up period. The cohort has a shorter LE (15.6 years) than the reference subjects (27.6 years), as depicted in Fig 1. QALE of the patients with pneumoconiosis after 50 years of extrapolation was 11.3 QALYs, with a loss of 13.9 QALYs relative to age- & gender-matched reference group, as illustrated in Fig 2.