[Investigation of the factors that contribute to the onset of insomnia in hypertensive patients by using a post-marketing surveillance database].

Many factors contribute to the onset of insomnia. However, few studies have identified the factors related to the onset of insomnia in hypertensive patients. We conducted a pharmacoepidemiologic study to examine the incidence of insomnia in hypertensive patients by using a post-marketing surveillance database. The insomnia onset was defined as the time of first prescription of hypnotics. The insomnia incidence rate in hypertensive patients under antihypertensive therapy was 0.77/100 person-years. The median insomnia onset date was 5 weeks. The insomnia type in 50.2% of the patients was difficulty in initiating sleep. We assessed the factors contributing to insomnia by using a nested case-control design. We selected 10 time-matched controls for every case. The hypotensive effect induced by antihypertensive therapy on the case group was lesser than that on the control group (p<0.01). The odds ratios (ORs) were estimated using multivariate conditional logistic regression. The factors contributing to insomnia onset were α blockers (OR, 2.38; 95% confidence interval [CI], 1.14-4.98), β blockers (OR, 1.54; 95% CI, 0.99-2.39), and calcium channel blockers (OR, 0.62; 95% CI, 0.43-0.90) compared with angiotensin-converting enzyme inhibitors; female sex (OR, 1.76; 95% CI, 1.27-2.44); complication of gastric/duodenal disorders (OR, 2.35; 95% CI, 1.14-4.86) or musculoskeletal system/connective tissue disorders (OR, 2.43; 95% CI, 1.23-4.79); and concomitant antihypertensive therapy (OR, 0.44; 95% CI, 0.31-0.63). This study identified the potential factors that may help to predict insomnia onset in hypertensive patients under antihypertensive therapy.