蒙古職業病研究(1986-2006)

Abstract

Objective: The purpose was to determine the incidence rates, time trends, and the standardized mortality ratios for major occupational diseases and to estimate the life expectancy (LE), quality-adjusted life expectancy (QALE), and their losses, in patients with pneumoconiosis in Mongolia. Methods: We retrieved information from all 4598 patients who were diagnosed and registered as having occupational diseases by the National Center of Workplace Condition and Occupational Diseases (NCWCOD) in Mongolia during 1986-2006. We established life tables for the registered cohort of occupational diseases and the general population of Mongolia by linking to all registered death certificates during the period 1986-2006, obtained from the State Centre for Civil Registration and Information. We estimated age-, gender-, and cause-specific mortality rate and standardized mortality ratio (SMR) for patients with occupational respiratory disease (n=1859). All patients diagnosed with occupational pneumoconiosis (n=432) were recruited, which were linked to the National Mortality Registry of Mongolia to obtain the survival function. We simulated the age, and the gender-matched reference group based on the life table in 2000. The survival ratio between patients and referents was used to extrapolate and calculate the life expectancy. The average expected years of life loss of pneumoconiosis was the mean lifetime survival difference between patients and referents. We adopted the utility values for workers with pneumoconiosis based on EQ-5D established by the UK studies, which were multiplied with the survival function to estimate the QALE. The loss of QALE from pneumoconiosis was calculated by subtracting the area under the quality-adjusted survival curve of pneumoconiosis from that of the age- & gender-matched referents. Throughout all the analysis, we used SAS software (SAS, NC, Version 9.1), LTAS.Net program and MC_QAS package. Results: There is a general increasing trend for new cases and incidence rates of reported occupational respiratory diseases (ORD), musculoskeletal disorders (MSD), cardiovascular diseases, skin diseases, toxic hepatitis, and noise induced hearing loss. The overall cumulative incidence rates in workers aged 30-59 years (CIR30-59) of ORD and MSD have increased from 3.0% to 4.4% and from 2.9% to 5.1%, respectively. A total of 98751.9 person-years at risk accrued, in which 405 cases (8.8%) were recorded as deceased during the observation period. SMRs were increased for occupational respiratory diseases (9.1, 95% CI of 7.7-10.7), lung cancer (10.1, 95% CI of 5.4-17.3) and pneumoconiosis (194.4, 95% CI of 163.2-229.8). One-third of the lung cancer cases were attributable to silicosis or anthraco-silicosis and 32.4% to asbestoses. There was no certified occupationally related mesothelioma, though its incidence and mortality rates increased during the last decade according to the national cancer registry of Mongolia. The life expectancy and EYLL of a patient with pneumoconiosis were 18.1 and 9.5 years, respectively; QALE and loss of QALE were 15.1 and 12.5 QALYs (quality-adjusted life years), respectively, indicating 45% of health gap. Conclusion: The industrialization of Mongolia over the last two decades has raised a concern on occupational health. There are increased incidences of occupational diseases during the last two decades because of the improvement of the surveillance system and expanded employment in industrial sectors of coal and metal ores mining, construction, and power generation. Such a rapid industrialization and development of the mining sector has contributed to an increasing trend of risk for mortality from occupational respiratory diseases and lung cancer in Mongolia. The health inequality for miners in Mongolia must be taken care of through proactive prevention, exposure monitoring and control, early diagnosis and management of pneumoconiosis. Actions must also be taken immediately to allocate more resources for the development of health manpower on early recognition of occupational diseases and establishment of a comprehensive hazard communication system.