- To explore gender differences in morbidity and total health care utilization 5 years prior to diagnosis of obstructive sleep apnea (OSA). Case-control study; patients were recruited between January 2001 and April 2003. Two university-affiliated sleep laboratories. 289 women (22-81 years) with OSA were matched with 289 men with OSA for age, body mass index (BMI), and apnea-hypopnea index (AHI). All OSA patients were matched 1:1 with healthy controls by age, geographic area, and primary physician. Women with OSA compared to men with OSA have lower perceived health status and Functional Outcomes of Sleep Questionnaire score (54.5% vs. 28.4%, P <0.05 and 67.5+/-21.4 vs. 76+/-20.1, P <0.05, respectively). Compared to men with OSA, women with OSA have higher risk of hypothyroidism (OR 4.7; 95% CI, 2.3-10) and arthropathy (OR 1.6, 95% CI, 1.1-2.2) and lower risk for CVD (OR 0.7; 95% CI, 0.5-0.91). Compared to controls, both women and men with OSA had 1.8 times higher 5-year total costs (P <0.0001). Compared to men with OSA, expenditures for women with OSA are 1.3 times higher (P <0.0001). The multiple logistic regression (adjusting for BMI, AHI) revealed that age (OR 1.04; 95% CI, 1.01-1.07), antipsychotic and anxiolytic drugs (OR 2.3; 95% CI, 1.2-4.4), and asthma (OR 2.4; 95% CI, 1.1-5.6) are independent determinants for "most costly" OSA women. Compared to men with similar OSA severity, women are heavier users of health care resources. Low FOSQ score and poor perceived health status in addition to overuse of psychoactive drugs are associated with high health care utilization among women with OSA.