We examined serum bilirubin and various liver-function enzymes as possible risk factors for angiographically documented coronary artery disease (CAD). The studies involved a "training" set of 619 men for whom complete data on all risk factors considered were available, and a "test" set of 258 men for whom some risk factor data were not available. In both study groups, the liver enzymes were not related to CAD; however, In[total bilirubin] was inversely and statistically significantly related to the presence of CAD, both univariately and multivariately after adjustment for the established risk factors of age, total cholesterol, high-density lipoprotein cholesterol, smoking history, and systolic blood pressure. A 50% decrease in total bilirubin was associated with a 47% increase in the odds of being in a more severe CAD category. Our data suggest that serum bilirubin is an inverse and independent risk factor for CAD, with an association equivalent in degree to that of systolic blood pressure.
This is the second of two studies done to determine whether moderate Gz exposure facilitates back disability. Cumulative trauma (repeated moderate to high G) exposures could be a precipitant of back pain in the military population. There is at present no reliable method of predicting who will suffer from back pain. We looked at officer back disability rates at separation from the Air Force (1972-1993). We compared non-rated Air Force officers to pilots and navigators exposed to low G and moderate to high G. We found no significant differences between aircrew and non-aircrew individuals until 1985, when the rates for aircrew fell below those of non-rated officers. Moderate G exposure does not seem to be a predictor of subsequent back disability. We recommend a larger prospective study of all rated and non-rated officers. We recommend that each separating officer undergo a detailed physical examination and answer a detailed back questionnaire.
Sandblom and colleagues state: "In a Cox proportional hazard analysis, the hazard ratio for death from prostate cancer was 1.23 (0.94 to 1.62; P=0.13) and 1.58 (1.06 to 2.36; P=0.024) after adjustment for age at start of the study." 1 Does the hazard ratio of 1.23 mean that being assigned to the uninvited group increases prostate cancer mortality by 23% compared with the invited group, or that only those in the uninvited group with prostate cancer have 23% more deaths than the invited group with prostate cancer? In other words, what is the denominator?Is the hazard ratio of 1.23 unadjusted for age at assignment while 1.58 was adjusted for age? Was adjustment for age pre-specified before the investigators analysed their death rates or was this post hoc analysis? If post hoc analysis, how many mortality risk factors were tested for an effect on case rate mortality? If the assignment to group was based on date of birth, the age distributions of the two groups should be nearly the same. Why then was the Cox proportional hazard analysis adjusted for age at the start of the study?Screening detects more slow growing or comparatively benign cancers such that case rate mortality with prostate cancers alone in the denominator will favour screening over no screening with fewer slow growing prostate cancers. Moreover, screening symptom-free men is intended to detect at an earlier stage before metastasis. Detecting any cancer at an earlier stage prolongs survival after diagnosis even if no treatment is given to any case in either group. Therefore both prostate cancer mortality and all cause mortality should be compared by assigned group beginning on the day of assignment, not day of diagnosis.
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