Document 8XkQN6QB1Dj8J4xrjpYgOQ1K

American Journal of Industrial Medicine 24:249-250 (1993) LETTER TO THE EDITOR Diagnostic Bias in Occupational Epidemiologic Studies Key words: vinyl chloride exposures, mortality study, emphysema, brain cancer The study of vinyl chloride workers by Wong et al. [1991] is an important contribution to our knowledge of the health of people occupationally exposed to this substance. However, the discussion of findings with respect to two causes of death does not include some results that affect their evaluation. One is the apparent excess of brain cancer. There is a good deal of data in the literature showing that diagnostic bias is important when one tries to attribute death to brain cancer [Greenwald et al., 1981; Helseth et al., 1988; Kurland et al., 1982]. In particular, Greenwald et al. [1981] have shown that an excess of brain cancer in Kodak employees was associated with more thorough diagnostic studies and access to comprehensive medical care, rather than with chemical exposure history. The study by Wong et al. [1991] does not discuss diagnostic bias as a possible explanation of special importance, all the more so since there is no firm confirmation of this finding in other studies [Doll, 1988]. The second finding, the significance of which is affected by other factors, is the excess in emphysema mortality. This is a finding with an inverse dose-response relationship based on duration of employment and an ambiguous relationship with latency, accompanied by a complementary deficit of an almost equal magnitude for deaths due to other nonmalignant respiratory diseases (which can be confused with emphysema). In 1988, Sir Richard Doll dismissed this excess emphysema mortality as not being an effect of vinyl chloride exposure because of such inconsistencies. . Readers who do not know the literature would not be able to put those findings from the Wong et al. [1991] study in perspective without this kind of information. Hasmukh C. Shah, PhD Chemical Manufacturers Association Washington, DC 23039001 Address reprint requests to Dr. H.C. Shah, Manager, Vinyl Chloride Panel, Chemical Manufacturers Association, 2501 M Street, NW, Washington, DC, 20037. Accepted for publication December 15, 1992. 1993 Wiley-Liss, Inc. SSOSY 250 Shah REFERENCES Doll R (1988): Effects of exposure to vinyl chloride. An assessment of the evidence. Scand J Work Environ Health 14:61-78. Greenwald P, Friedlander BR, Lawrence CE (1981): Diagnostic sensitivity bias--An epidemiologic explanation for an apparent brain tumor excess. J Occup Med 10:690-694. Helseth A, Langmark F, Mork S (1988): Neoplasms of the central nervous system in Norway. 0. Descriptive epidemiology of intracranial neoplasms 1955-1984. APMIS 96:1066-1074. Kurland, L. Schoenberg BS, Annegers JF, Okazaki H, Molgaard CA (1982): The incidence of primary intracranial neoplasms in Rochester, Minnesota, 1935-1977. Ann NY Acad Sci 381:6-16. Wong O, Whorton MD, Follait DE, Ragland D (1991): An industry-wide epidemiologic study of vinyl chloride workers, 1942-1981. Am J Ind Med 20:317-334. 2383900, BFG27955 to