- OBJECTIVES: To determine whether elderly subjects with obstructive sleep apnea (OSA) had different morbidity and health care utilization than elderly subjects without OSA and middle-aged patients with OSA 2 years before diagnosis. DESIGN: Case-control study between January 2001 and April 2003. SETTING: Two sleep–wake disorders centers. PARTICIPANTS: One hundred fifty-eight elderly and 1,166 middle-aged (aged 67–89 and 40–64, respectively) patients with OSA were matched 1:1 with healthy controls according to age, sex, geographic area, and primary physician. MEASUREMENTS: Polysomnography, medical diagnoses, and healthcare utilization. RESULTS: Healthcare costs 2 years before diagnosis were more than 1.8 times as high for elderly and middle-aged patients with OSA as for controls (P<.001). Expenditures of elderly patients with OSA were 1.9 times as high as for middle-aged patients with OSA (P<.001). Multiple logistic regression analysis (adjusting for age, body mass index, and apnea hypopnea index) revealed that cardiovascular disease (CVD) (odds ratio (OR)=4.1, 95% confidence interval (CI)=1.8–9.3) and use of psychoactive drugs (OR=3.8, 95% CI=1.5–10.1) are independent determinants for the top-third most-costly elderly patients with OSA. CONCLUSION: Elderly patients with OSA have high healthcare utilization because of CVD morbidity and use of psychoactive medications. Therefore, OSA has clinical significance in elderly people.