Study cohort characteristics
diabetes, cardio-vascular disease, SDB
DIABETES
In interpreting our results it is important to understand the characteristics of the study cohort. This was not a randomised community-recruited population-based study. We targeted a specific clinic group (i.e. patients referred to a sleep clinic for assessment of SDB) and then screened for and eliminated diabetes as a cardio-vascular risk factor. Consequently, our study group was also not a generalised sleep clinic population sample. Rather, we aimed to test for associations between specific SDB metrics and specific micro-vascular characteristics (retinal vessel calibre) in an environment where the influence of known cardio-vascular disease risk factors was absent, minimised or controlled. The rationale for this approach assumed that SDB influences were likely to be small compared with well-known systemic risk factors, such as diabetes, and therefore, would be more likely detected in the absence of such major confounders. Previous published studies that have attempted to quantify associations between retinal vessel calibre and SDB have not attempted to minimise other cardiovascular risk factors [