Of the 149 cases and controls 33 (22%) and 17 (11%) were treated with any sympathomimetic agent, yielding a crude OR of 2.2 (95% confidence interval [CI], 1.2-4.3). We adjusted for a number of possible confounders, notably, sex, age, prior hospitalizations for arrhythmia, asthma, COPD, myocardial infarction, and angina pectoris. In addition, we adjusted for the use of a broad range of drugs that may have direct proarrhythmic effects, give rise to hyperkalemia or hypokalemia, or are markers for a history of rhythm disturbances, such as digoxin, calcium channel inhibitors, β-blockers, oral anticoagulants, antiarrhythmics, angiotensin-converting enzyme inhibitors, corticosteroids, laxatives, diuretics, nitrates, neuroleptics, H1-antihistamines, antidepressants, and ibopamin. Adjusted ORs were 4.0 (95% CI, 1.0-15.1) for the use of any sympathomimetic drug and 15.7 (95% CI, 1.1-228.0) for the use of systemic sympathomimetic drugs (Table 2). Separate ORs for inhalation and nasal sympathomimetics and theophylline were not significantly associated with hospitalization for arrhythmia.