Sleep-Disordered Breathing as a Risk Factor for Cerebrovascular Disease

Background and Purpose— The evidence that obstructive sleep apnea/hypopnea (OSAH) is a risk factor for ischemic cerebrovascular disease is inconclusive. We explored this relationship in transient ischemic attack (TIA) patients because they are less likely than stroke patients to have OSAH as a consequence of cerebrovascular disease.Methods— We performed a case-control study among 86 patients with TIA from a hospital neurovascular clinic, matched for age (±5 years) and sex with controls from the referring local family practice registers.Results— Forty-nine of the 86 matched pairs were male and the body mass index was similar among cases and controls. The primary outcome measure, the apnea/hypopnea index [AHI=number of (apneas+hypopneas)/h slept, measured during overnight polysomnography and scored blind to case-control status], was the same for cases and controls (21/hour). However, the median number of 4% desaturations during sleep was slightly greater in the cases (12/hour) than controls (6/hour,P =0.04). There were the expected associations between TIA and higher fibrinogen levels (TIA 3.3, control 3.0 g/L,P =0.01), previous myocardial infarction (TIA 22, control 6%,P =0.007), a history of ever smoking (TIA 71, control 54%,P =0.01), hypertension (TIA 51, control 21%,P =0.001), and raised cholesterol (TIA 27, control 10%,P =0.01), with a weak trend for diabetes mellitus (TIA 10, control 6%,P =0.4).Conclusion— OSAH does not appear to be strongly associated with TIAs.