Scientific standards and the design of case-control research

Risk for delirium tremens in patients with alcohol withdrawal syndrome

To determine the characteristics associated with an increased risk for delirium tremens (DT) we performed a case-control study at the detoxification units of two hospitals. Cases met DSM-IV criteria for DT. For each case (n = 15), 3 controls (n = 45) were chosen. Eligibility criteria were applied equally to cases and controls. Cases were more likely than controls to report a prior complicated withdrawal (DT or alcohol withdrawal seizure) (53 vs. 27%, OR 3.1, 95% CI 0.94-10.55), have a systolic blood pressure greater than 145 mm Hg on admission (60 vs. 27%, OR 4.1, 95% CI 1.21-14.06), and have comorbidity scores of at least 1 (60 vs. 18%, OR 6.9, 95% CI 1.92-25.08). Zero cases (0%) and 15 (33%) controls had no prior complicated withdrawals and no adverse clinical features (systolic blood pressure >145 or comorbidity score >1). Compared to this group, the odds of being a case and having both prior complicated withdrawal and at least 1 adverse clinical feature was 44.8 (95% CI 4.36-460). Elevated blood pressure, prior complicated alcohol withdrawal and medical comorbidity, alone and in combination, are associated with an increased risk of delirium tremens.

Hospitalizations for aplastic anemia and agranulocytosis in Saskatchewan: incidence and associations with antecedent prescription drug use

A population-based study to estimate the incidence of hospitalizations for aplastic anemia and agranulocytosis and to evaluate associations between these disorders and antecedent prescription drug use was performed using the Saskatchewan administrative health care databases. Hospital charts and cancer registration data were utilized to apply strict diagnostic criteria to case identification. Estimates of the annual incidence of aplastic anemia and agranulocytosis were 2.7 and 3.0 per million, which are similar to those from other recent population-based studies with comparable case identification criteria. Only a small number of cases were available to evaluate potential drug causes, leading to an analysis of limited power. Nevertheless, significant associations were found between aplastic anemia and tocainide, gold salts, and antidepressants; and between agranulocytosis and anti-thyroids, trimethoprim-sulfamethoxazole, beta-lactams, sulfasalazine, chlorpromazine, carbamazepine, glyburide, and procainamide, although the associations with antibiotics may indicate a response to the disorders rather than a possible cause. These findings are generally consistent with the results of other case-control investigations.