摘要：Objectives. We examined the potential influences of certain selection factors on the utility of the Coal Workers’ Health Surveillance Program (CWHSP) data for tracking disease distribution and trends. Methods. We combined data from the CWHSP and the Energy Information Administration to examine any influence of variable worker participation on observed disease prevalence. We evaluated effects of differential participation by coal mining region, temporal changes in employment, and active surveillance efforts. Results. The published findings of pneumoconiosis distribution and trends from the CWHSP were robust compared with the various participation factors that might have affected their validity for population-based estimates of disease burden. Exploration of factors that could potentially bias the findings generally led to small increases in the primary estimates, mostly for the early years of the program. Conclusions. We confirmed previously reported findings that there was a high prevalence of coal worker pneumoconiosis (CWP) around 1970–1974, a substantial decline in 1995–1999, and indications of an increase since then. Overall our findings suggest that the previously reported distribution and trends in CWP prevalence were broadly accurate. Twenty years ago, the National Institute for Occupational Safety and Health (NIOSH) reported on the trend in pneumoconiosis prevalence among US coal miners for 1970–1986. 1 The primary conclusions from those data were that the reduction in underground coal mine dust exposure mandated by federal regulations in 1969 led to lower prevalence of pneumoconiosis among underground coal miners. Overall, these results and conclusions were uncontroversial. Since that time, NIOSH has continued to report findings from the Coal Workers’ Health Surveillance Program (CWHSP) in the scientific literature, 2 in government reports, 3,4 and on the NIOSH Web site. 5,6 Figure A (available as a supplement to the online version of this article at http://www.ajph.org ) shows trends in the national prevalence of coal worker pneumoconiosis (CWP) from 1970 to 2009 as reported on the Web site in early 2012. In addition to showing the previously reported decline in prevalence from 1970 to 1986, it also indicates an increase in CWP prevalence in recent years. NIOSH and others have recently reported on and investigated this phenomenon. 7–15 These more recent findings have generated concern among the public health community and others. 16–19 In reporting CWHSP statistics, NIOSH is aware that the data are collected primarily for worker monitoring. That is, the purpose is to prevent CWP progression in affected miners via secondary prevention. The use of any data for public health surveillance is potentially vulnerable to various factors that could affect its integrity and validity. For instance, these data are susceptible to potential biases from worker participation and selection effects, as well as to effects related to temporal changes in employment and participation among coal mining regions across the country. Coal is ranked based on carbon content, with the highest rank coals (those with the highest carbon content) associated with increased risk of development and progression of CWP. We compiled this report to examine such issues. Our objectives were to formally address the following questions. (1) Do the overall data, as shown in Figure A, provide an accurate picture of temporal trends in national pneumoconiosis prevalence among underground coal miners? (2) Do the national figures conceal trends of concern or interest in specific regions? (3) Are there factors that affect the utility of the program data for population-based surveillance?
