American journal of epidemiology
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Meta Analysis
Antiviral effects on influenza viral transmission and pathogenicity: observations from household-based trials.
Four household-based, randomized clinical trials, two each of zanamivir and oseltamivir, were designed primarily to estimate the effect of postexposure prophylaxis on preventing influenza illness in household contacts. However, the effect of influenza antivirals on infectiousness as well as on the ability of the virus to cause disease--the pathogenicity--have important public health consequences. The authors show how such studies can provide estimates of pathogenicity, antiviral efficacy for pathogenicity, and the antiviral effect on infectiousness. ⋯ Pathogenicity in controls ranged from 44% (95% CI: 33, 55) to 66% (95% CI: 48, 72). Efficacy in reducing pathogenicity for zanamivir was 52% (95% CI: 19, 72) and 56% (95% CI: 14, 77) in the two studies; for oseltamivir, it was 56% (95% CI: 10, 73) and 79% (95% CI: 45, 92). Studies of influenza antivirals in transmission units would be improved if randomization schemes were used that allow estimation of the antiviral effect on infectiousness from individual studies.
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Women with a previous stillbirth are known to be at increased risk of stillbirth in subsequent pregnancies. However, few studies have addressed the association between other complications of pregnancy and the future risk of stillbirth. Using linkage of national pregnancy and perinatal death registries, the authors performed a retrospective cohort study of 133,163 women having a second birth in Scotland between 1992 and 2001 whose first infant was liveborn. ⋯ There was a statistically significant positive interaction between previous delivery of a SGA infant and previous preeclampsia (p = 0.01): Women with this combination in their first pregnancy had an approximately fivefold risk of unexplained stillbirth in the second pregnancy (HR = 4.95, 95% CI: 2.63, 9.32). Associations were stronger with SGA unexplained stillbirths. The authors conclude that complicated first births of liveborn infants are associated with an increased risk of unexplained stillbirth in the next pregnancy.
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Pollution from motor vehicles constitutes a major environmental health problem. The present paper describes associations between diesel and gasoline engine emissions and lung cancer, as evidenced in a 1979-1985 population-based case-control study in Montreal, Canada. Cases were 857 male lung cancer patients. ⋯ When population controls were studied, the odds ratios, after adjustments for potential confounders, were 1.2 (95% confidence interval: 0.8, 1.8) for any exposure and 1.6 (95% confidence interval: 0.9, 2.8) for substantial exposure. Confidence intervals between risk estimates derived from the two control groups overlapped considerably. These results provide some limited support for the hypothesis of an excess lung cancer risk due to diesel exhaust but no support for an increase in risk due to gasoline exhaust.