Association of Obstructive Sleep Apnea Diagnosis and Incidence of Subsequent Stroke Diagnosis Among Veterans

Introduction: Obstructive sleep apnea (OSA) is associated with long-term health outcomes. We aimed to test the association between preexisting OSA diagnosis and subsequent incident stroke diagnosis in a large long-term cohort of veteran patients.

Methods: This retrospective cohort study included all veteran patients diagnosed with OSA between 1993 and 2013 by ICD-9 diagnosis codes in any Veterans Affairs facility and veteran patients without an OSA diagnosis, matched by age and index year. First stroke diagnoses were identified by ICD-9 codes for the time-period at least 2 years after OSA diagnosis to avoid reverse causality. We tested the association between OSA diagnosis and subsequent incident stroke diagnosis using multivariate Cox regression adjusting for potential confounders.

Results: The cohort included 1,711,979 patients (853,300 with and 858,679 without an OSA diagnosis), mean age 57+/-13 years, predominantly male (95%), a minority with an obesity diagnosis (32%), and median follow-up 5.9 years (range, 3.7-8.9). The proportion of patients diagnosed with stroke was higher in those with vs without an OSA diagnosis (2.0% vs 0.8%; mean difference 1.2%; 95% confidence interval [CI], 1.2%-1.3%; p< 0.001). After adjusting for age, sex, race, smoking status, alcohol use, obesity, index year, and comorbidity, the hazard of incident stroke was 4% higher in patients with vs without an OSA diagnosis (hazard ratio, 1.04; 95% CI, 1.01-1.07; p=0.008). Obesity diagnosis and male sex had greater independent associations with stroke diagnosis.

Conclusions: Preexisting OSA diagnosis is independently associated with incidence stroke diagnosis in this large veteran cohort. Future mediation analyses will help determine the relative impact of OSA versus other risk factors where they share a common causal pathway.