Lifestyle variables and the risk of myocardial infarction in the General Practice Research Database

<p>Abstract</p> <p>Background</p> <p>The primary objective of this study is to estimate the association between body mass index (BMI) and the risk of first acute myocardial infarction (AMI). As a secondary objective, we considered the association between other lifestyle variables, smoking and heavy alcohol use, and AMI risk.</p> <p>Methods</p> <p>This study was conducted in the general practice research database (GPRD) which is a database based on general practitioner records and is a representative sample of the United Kingdom population. We matched cases of first AMI as identified by diagnostic codes with up to 10 controls between January 1^st, 2001 and December 31^st, 2005 using incidence density sampling. We used multiple imputation to account for missing data.</p> <p>Results</p> <p>We identified 19,353 cases of first AMI which were matched on index date, GPRD practice and age to 192,821 controls. There was a modest amount of missing data in the database, and the patients with missing data had different risks than those with recorded values. We adjusted our analysis for each lifestyle variable jointly and also for age, sex, and number of hospitalizations in the past year. Although a record of underweight (BMI <18.0 kg/m²) did not alter the risk for AMI (adjusted odds ratio (OR): 1.00; 95% confidence interval (CI): 0.87–1.11) when compared with normal BMI (18.0–24.9 kg/m²), obesity (BMI ≥30 kg/m²) predicted an increased risk (adjusted OR: 1.41; 95% CI: 1.35–1.47). A history of smoking also predicted an increased risk of AMI (adjusted OR: 1.81; 95% CI: 1.75–1.87) as did heavy alcohol use (adjusted OR: 1.15; 95% CI: 1.06–1.26).</p> <p>Conclusion</p> <p>This study illustrates that obesity, smoking and heavy alcohol use, as recorded during routine care by a general practitioner, are important predictors of an increased risk of a first AMI. In contrast, low BMI does not increase the risk of a first AMI.</p

A case-control study examining the association between travel and deep venous thrombosis /

Background. This thesis explores the link between travel and deep venous thrombosis (DVT). While it is biologically plausible that prolonged travel is an independent risk factor for venous thromboembolic disease (VTE), epidemiological data to date are conflicting.Aim. To determine whether there is a independent association between travel and DVT.Methods. This was a multi-center case control study. Consecutive patients presenting to the vascular laboratory with clinically suspected DVT were eligible to participate. Cases were patients with confirmed DVT; controls were patients who had DVT ruled out. Travel history and clinical characteristics were determined though standardized interviewer-administered questionnaire. Genetic testing of Factor V Leiden and Prothrombin gene mutations were also performed. SAS was used to perform unconditional multivariate logistic regression analysis.Results. There were 359 cases and 359 controls. The crude and adjusted odds ratios (OR) for travel and DVT were 1.15 (95%CI: 0.78, 1.69) and 1.51 (95%CI: 0.91, 2.50) respectively. Travel of >=12 hours' duration had a higher OR estimate (2.82, 95%CI: 0.52, 15.24) than shorter travel durations (OR = 1.32, 95%CI: 0.63, 2.76), although this did not reach statistical significance. Analyzing plane and car travel separately showed that plane travel of >=12 hours duration had a crude and adjusted OR of 8.22 (95%CI: 1.02, 66.05) and 7.10 (95% CI: 0.70, 72.35). No such association was found with long durations of car travel.Interpretation. Plane travel appears to be a mild independent risk factor for DVT overall, although the adjusted OR does not achieve conventional levels of statistical significance. Plane travel durations of 12 hours or longer had the highest estimate of risk. This was not found to be true of car travel. These findings may have future implications regarding the use of thromboprophylaxis in travelers