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Background Acute hand injury is the leading cause of occupational injury treated in United States' hospital emergency departments (e.g., laceration, crush or fracture). To identify risk factors for traumatic hand injuries, we conducted a case-crossover study of transient exposures (e.g., being rushed) for acute occupational traumatic hand injury. Methods The case-crossover method, which uses subjects as their own controls, was used to identify risk factors for occupational hand injury. Two hundred and thirty-two subjects were recruited from 17 occupational health clinics in New England and interviewed by telephone a median of 1.2 days after their injury. The a priori hazard period was de®ned as 10 min before the injury. Two control periods were used: one was 60±70 min prior to the injury (matched-pair interval analysis); the other was the total work-time exposed, on average, in the previous month (usual frequency analysis). Results In the usual frequency analysis, the relative risk for using malfunctioning or different-from-usual equipment or tools in the hazard period was 25.5 (95% con®dence interval 18.4±35.2). Relative risks were also signi®cantly elevated for performing a task using an unusual work method, doing an unusual task, being distracted, or being rushed. Wearing gloves appeared to be protective (relative risk 0.8, 95% CI 0.5± 1.2). Matched-pair interval analysis, where appropriate, provided similar ®ndings but had much wider con®dence intervals. Conclusions This study demonstrates that the case-crossover design is a feasible and ef®cient method for studying transient risk factors for sudden-onset traumatic occupational hand injury. The usual frequency analysis proved more useful than the match-pair approach to control period selection.

In a population-based case-control study of parous women less than 45 years of age, we evaluated the relations of various pregnancy characteristics to maternal breast cancer risk. Cases (N = 1,239) diagnosed with in situ or invasive breast cancer from 1990 to 1992 in Atlanta, GA, Seattle/Puget Sound, WA, and five counties in central New Jersey, and population controls (N = 1,166) identified by random-digit dialing, were interviewed regarding the details of their pregnancies. We used logistic regression to estimate relative risks (RR) and 95% confidence intervals (CI) and to adjust for breast cancer risk factors. Women who reported nausea or vomiting in their first pregnancy had a slightly lower risk of breast cancer (RR = 0.87; 95% CI = 0.72-1.0). We found no strong or consistent associations for maternal risk related to gestational length, pregnancy weight gain, gestational diabetes, pregnancy hypertension, or gender of the offspring, although we found some evidence for reductions in risk for toxemia (RR = 0.81; 95% CI = 0.61-1.1) and specific sex (RR for female twins vs singletons = 0.48; 95% CI = 0.20-1.3) and timing characteristics of twinning. Overall, these data provide little support for the hypothesis that pregnancy hormone levels are associated with subsequent maternal risk of breast cancer in young women.

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Background-While several studies have examined associations between temperature and cardiovascular-disease-related mortality, fewer have investigated the association between temperature and the development of acute myocardial infarction (MI). Moreover, little is known about who is most susceptible to the effects of temperature. Methods-We analyzed data from the Worcester Heart Attack Study, a community-wide investigation of acute MI in residents of the Worcester (MA) metropolitan area. We used a casecrossover approach to examine the association of apparent temperature with acute MI occurrence and with all-cause in-hospital and post-discharge mortality. We examined effect modification by sociodemographic characteristics, medical history, clinical complications, and physical environment. Results-A decrease in an interquartile range (IQR) in apparent temperature was associated with an increased risk of acute MI on the same day (hazard ratio=1.15 [95% confidence interval= 1.01-1.31]). Extreme cold during the 2 days prior was associated with an increased risk of acute MI (1.36 [1.07-1.74]). Extreme heat during the two days prior was also associated with an increased risk of mortality (1.44 [1.06-1.96]). Persons living in areas with greater poverty were more susceptible to heat.

We thank Dr Palatini for his discussion of how the relationship between coffee consumption and heart failure may be impacted by the CYP1A2 gene. As we noted 1 , previous studies have shown that the CYP1A2 gene modifies the association between coffee consumption and myocardial infarction. We agree that further research is necessary to examine whether the presence of certain polymorphisms also modify the risk of developing heart failure. In our meta-analysis, we summarized the findings from 5 studies that showed only moderate between-study heterogeneity (I 2 =37.5%); only one 2 of the included studies reported an increased risk of heart failure with higher levels of coffee consumption, but it did not include adjustment for any potential confounders. It is possible that the results were consistent because all the included studies were conducted in Sweden and Finland, countries that may have a similar prevalence of allele frequencies for the CYPIA2 gene. Further work is needed to examine whether the relationship is affected by gene and environment interactions. DisclosuresNone. References