Case-control study of cancer risk in tetraethyl lead manufacturing.

A case-control study was conducted to investigate the relative risk of cancer detection among Du Pont employees who worked in a tetraethyl lead (TEL) manufacturing area. The study's objective was to determine whether the employees' risk of developing or dying from cancer was associated with occupational exposure to TEL. All malignant neoplasms detected in the active and pensioned employee population during the period 1956-1987 were studied. TEL exposure was estimated by the following measures: ever employed in the TEL area, years of employment in TEL, TEL exposure rank, and the TEL cumulative exposure index. TEL manufacturing exposed employees to both organic and inorganic lead compounds. Because the underlying data did not permit the exposure assessment to distinguish between organic and inorganic lead, the TEL exposure measures reflect exposure to the TEL manufacturing process itself. The effects of latency, cigarette smoking habits, and exposures to other known or suspected carcinogens at the plant were also assessed. A strong association was observed between exposure to the TEL manufacturing process and rectal cancer (the odds ratio was 3.7 with 90% confidence limits of 1.3-10.2 for the analysis of ever/never exposed to TEL). An exposure-response relationship was noted with a fourfold elevation in the odds ratio at the high-very high cumulative exposure level. These patterns were even more pronounced after assuming a 10 year latency. Similar results were obtained for cancers of the sigmoid colon. These findings suggest that exposure to the TEL manufacturing process may have played a causal role in the colorectal cancer experience at the plant. This position is supported by the graded exposure-response relationships, the consistency of the results across exposure measures, the specificity of the health outcome (i.e., colorectal cancer), and the strength of the association. However, the evidence for causality is not compelling. This is the first report of an association between TEL manufacturing and colorectal cancer, and the evidence is compatible with a wide range of causal (i.e., indirect vs. direct acting; initiating vs. promoting) and noncausal (i.e., statistical and methodological bias; coincidence) interpretations.

Does physician performance explain interspecialty differences in malpractice claim rates?

Physician specialty has been consistently associated with different malpractice claim rates, with neurosurgery, orthopedics, and obstetrics and gynecology having the highest rates. Whether these differences reflect physician performance or other aspects of patient care that are unique for each specialty is unclear. A retrospective cohort study was performed including 12,829 physicians involved in 8,221 closed cases from 1977 to 1991. For each case an assessment was made whether the plaintiff received an award and whether the physician care of the patient was indefensible. An award was made to the plaintiff in 42% of cases. Physician care was considered indefensible in 23% of the cases. The specialties with the highest award rates were anesthesiology (58.3%), obstetrics and gynecology (47.5%), and radiology (43.0%). Neurosurgery had the lowest rate of award (30.2%). The specialties with the highest indefensibility rates were radiology (36%), obstetrics and gynecology (27%), and anesthesiology (27%). Neurosurgery had the lowest indefensibility rate (10%). These results were unchanged after controlling for physician age, degree, site of training, certification status, and severity of patient injury. In conclusion, differences in award rate and indefensibility are present, but not large enough to explain the large variation in specialty claim rates. This suggests that the variation in malpractice rates results from factors other than a meaningful difference in physician performance.

Physician demographics and the risk of medical malpractice.

PURPOSE: This study was undertaken to clarify which, if any, physician demographic characteristics are associated with an increased rate of medical malpractice claims. METHODS: We analyzed the malpractice experience of 9,250 physicians insured for at least 2 years from 1977 to 1987 in the state of New Jersey. After adjusting for years at risk, physician claims per year was categorized into low, medium, and high. RESULTS: Male physicians were three times as likely to be in the high-claims group as female physicians, even after adjusting for other demographic variables (relative risk, 3.1; 99% confidence interval, 2.2 to 4.4). Specialty was strongly associated with claims rate, with neurosurgery, orthopedics, and obstetrics/gynecology having 7 to 12 times the number of claims per year as psychiatry, the specialty with the fewest claims. The rate of claims varied with age (p < 0.001) and peaked at approximately age 40. No association was evident between claims rate and a physician's site of training or type of degree. CONCLUSION: Male physicians are three times as likely to be in a high-claims category as female physicians. We suspect that the most likely explanation for this finding is that women interact more effectively with patients. Understanding the reasons for the variation in claim rates between physicians may lead to the development of methods to reduce the overall rate of malpractice claims.

Epidemiologic study of lung cancer mortality in workers exposed to titanium tetrachloride.

A study was done to examine whether workers exposed to titanium tetrachloride had significantly higher risks of lung cancer, chronic respiratory disease, pleural thickening/plaques, or pulmonary fibrosis than referent groups. A total of 2477 employees from two titanium dioxide plants were studied. Of that group, 969 employees exposed to titanium tetrachloride were observed from 1956 through 1985 for cancer and chronic respiratory disease incidence and from 1935 through 1983 for mortality. A cross-sectional sample of 398 employees was evaluated for chest roentgenogram abnormalities. Cohort analyses showed that the risk of developing lung cancer and other fatal respiratory diseases was not statistically significantly higher for the titanium tetrachloride-exposed workers than for the referent group. Nested case-control analyses found no statistically significant association between titanium tetrachloride exposure and risk of lung cancer, chronic respiratory disease, and chest roentgenogram abnormalities. No cases of pulmonary fibrosis were observed among titanium tetrachloride-exposed employees. Smoking was found to be a strong predictor of lung cancer mortality in the nonexposed employees with an increased risk of dying from lung cancer up to 7-fold higher in current smokers than in nonsmokers.