Seasonal fluctuations of cardiovascular risk markers in patients referred to coronary angiography.

Seasonal variation in cardiovascular disease (CVD) is well documented. Data on seasonal fluctuations in cardiovascular risk markers are relatively sparse but may be relevant for CVD risk classification and treatment. We aimed to quantify the presence, magnitude, and timing of seasonality across various cardiovascular risk markers in patients referred to coronary angiography. In this retrospective, cross-sectional study, we analysed cardiovascular risk markers in 3316 patients referred to coronary angiography between July 1997 and January 2000 from the Ludwigshafen Risk and Cardiovascular Health (LURIC) study. Seasonal patterns were assessed using robust cosinor regressions, while correcting for age and sex. For each cardiovascular risk marker, we evaluated seasonality, peak date and magnitude (difference between peak and nadir) of seasonal fluctuations. Accordingly, we analysed 24 different cardiovascular risk markers and corrected for the false discovery rate (FDR). Overall, 16 cardiovascular risk markers showed significant seasonal dependency, of which the following had Cohen's d higher than 0.2 (peak-nadir difference): 25-hydroxyvitamin D (10.28 ng/mL), LDL cholesterol (15.36 mg/dL), HbA1c (0.31%), Omega-3 Index (0.45%), HDL (3.18 mg/dL), HOMA Index (0.54), calcium (0.03 mmol/L), and ApoB (5.6 mg/dL). Timing of peaks varied starkly. The seasonality in cardiovascular risk markers of patients referred to coronary angiography indicates that diagnostic and therapeutic thresholds for these markers should consider the date of assessment. Diverse seasonality timings suggest that the underlying mechanisms for seasonal fluctuations are likely multifactorial. Further research should evaluate the individual and environmental factors that may cause these seasonal fluctuations.