Impact Resulting from Serious Occupational Injuries: Estimation of Years of Potential Life Lost and Monetary Value of Physical Pain

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The thesis was comprised of three papers. In the first paper, we assessed the life expectancy lost and potential work life lost resulting from cases of mortality and permanent disability by different types of occupational injuries during 1986-2000 in Taiwan. Databases of occupational mortality and permanent disability during 1986-2000 were retrieved from the Bureau of Labor Insurance, which were linked with the database of national death registry to construct the survival function. Then, a Monte Carlo simulation method was used to extrapolate the survivors up to 600 months to derive the life expectancy for different injury cases with permanent disability (n=81,249). For the mortality cases (n=20,001), the life expectancy lost were estimated by gender-, age-matched based on the life table of each calendar year. For occupational permanent disability, different types of injury showed variations of YPLL (years of potential life lost) ranged from 13.6 years to 7.4 years per case. The overall YPLL of occupational permanent disability is almost the same as that of occupational mortality, with a ratio of 1.04:1. After accounting for permanent impairment of working ability and assuming a uniform retirement age of 65, the YPWLL (years of potential work life lost) due to occupational permanent disability is about 62% of that resulting from occupational mortality. We concluded that permanent disability resulting from occupational injuries has a significant impact on society. Our estimations can provide empirical basis for both the health policy decision and improvement of the equity and efficiency of workmen compensation system in Taiwan and possibly other newly developed countries. In the second paper, the objectives of the study are to estimate the life expectancy and exploring the determinants of survival for workers with occupational permanent disability. Databases of occupational permanent disability during 1986-2000 were retrieved from the Bureau of Labor Insurance and linked with the database of national death registry to construct the survival function. A Monte Carlo simulation method was used to extrapolate the survivors of up to 600 months to derive the life expectancy for different types of occupational injuries with permanent disability (n=81,249). The Cox (proportional hazards) regression was conducted to explore the determinants and estimate the hazard ratios. We included demographic variables including age, gender, insured wage, severity of disability, injury causes, and organ-system disability into the model as the covariates. The results showed that workers with occupational permanent disability survived shorter than the general population after injury, giving estimated years of life loss ranged from 9 to 19 years. After the adjustment of age and gender, we found that a higher severity of disability, impairment of vital organ or lower extremities, and a lower insured wage were significantly associated with shorter survival. Injury types of struck by sliding objects, transportation, trip/slip, and tumble down showed hazard ratios between 1.24 – 1.34 compared with injury by caught in. We concluded that workers with occupational permanent disability survived shorter than general population. Our findings identified major determinants to predict survival for workers with occupational permanent disability, which may be used to improve the equity for workmen compensation system. Finally, within the process of calculating the true costs of illness, physical pain is a component of intangible, or human, costs. One method of estimating the monetary value of such costs is the ‘contingent valuation method’ (CVM), a stated preference method based upon the elicitation of levels of willingness to pay (WTP) facilitated through surveys. This study is amongst the first of its kind to apply CVM to the estimation of the cost of the removal of physical pain resulting from permanently-disabling occupational injuries. We assume that a painkilling drug has been invented to mitigate physical pain with the advantages of validity and instantaneity, and without any side effects. The WTP of each of the respondents is determined by a two-step sequential-bidding process. The maximum WTP under log normal distribution was NT$1,791/day (US$ 65.1), whilst under Weibull distribution it was NT$1,913/day (US$ 69.6). Older respondents, those with higher household income, fall injuries, longer periods of hospitalization, or with a perceived demand for the painkilling drug in excess of one day, displayed a positive independent effect on the eliciting of their WTP. In addition, respondents with higher ‘out of pocket’ expenses, or where the interview took place two years or more after the injury occurred, responded with a lower WTP.