Wern Yew Ding, MBChB
Intracerebral hemorrhage (ICH) is a life-threatening condition associated with poor prognosis. About one in three patients die within the first month of an event. Among those who survive, severe functional disability often ensues. Concerningly, there is no definitive medical treatment for ICH, and the role of surgery remains debatable despite its use in various forms. Hence, the best treatment for ICH may ultimately be prevention. For the prevention of ICH, it is important that the relevant risk factors are identified and managed accordingly.
In this brief report from Geer et al., the authors evaluated the effects of obstructive sleep apnea (OSA) as an independent risk factor for non-traumatic ICH. This was predicated on the premise that OSA causes a cycle of abnormal physiology including hypoxaemia, sympathetic activation, and hemodynamic disturbance, and shares common pathophysiology with ICH. For this analysis, 5808 patients were enrolled as part of the multicenter, case-controlled ERICH (Ethnic/Racial Variations of Intracerebral Hemorrhage) study. Controls were selected at random, independent of exposure, to balance cases by age, sex, race/ethnicity, and metropolitan area. The risk of OSA was determined using the Berlin Questionnaire (BQ), which has previously been validated for this purpose and classifies patients as high or low risk. Patients with non-traumatic ICH had significantly higher rates of OSA compared to controls (OR 2.28 [95% CI, 2.05 – 2.55]). Furthermore, OSA was an independent risk factor for ICH in this patient cohort after controlling for potential confounders.
There are a few items worth noting from this study. Firstly, being identified as high risk of OSA using the BQ is not diagnostic for the condition, which requires polysomnography. Secondly, of the 2896 patients who had completed the BQ, 1600 were done by proxy, which introduces the possibility of diagnostic misclassification. Nonetheless, patients at high risk of OSA, as identified by the BQ, were more likely males with hypertension, coronary artery disease, diabetes mellitus, hyperlipidaemia and higher mean body mass index. These are all known risk factors for OSA and, therefore, provide some reassurance towards the use of the BQ in this manner. Thirdly, it appears surprising that increasing age and alcohol use were found to be protective against ICH within the multivariable logistic regression model. Overall, this is an important topic and the role and mechanism(s) by which OSA may contribute to ICH warrant further investigation.
