Increasing high-density lipoprotein cholesterol relative to total cholesterol may increase the risk of stroke
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Although the inverse relationship between high-density lipoprotein (HDL)-cholesterol and coronary heart disease (CHD) is well established, the association between HDL-cholesterol and stroke is less clear, even when analyses are restrained to ischaemic stroke, which partake of a common aetiology with CHD. The study was conducted in order to investigate the relationship between HDL-cholesterol and stroke, especially for stroke subtypes. To this end, Cox survival models were applied to about 80000 participants of 25 cohort studies from the Asia Pacific Cohort Studies Collaboration, yielding an overall cohort with relatively high number of both stroke and CHD events and median follow-up of 6.8 years. After adjusting for age and regression dilution, hazard ratios for a 1 standard deviation (SD) towards lower HDL-cholesterol were 1.39 for CHD events, 0.90 for ischaemic stroke and 0.89 for haemorrhagic stroke. As total cholesterol (TC) increased relative to HDL-cholesterol, the risk of CHD increased, the risk of ischaemic stroke remained unchanged whilst the risk of haemorrhagic stroke decreased, a 1 SD increase in TC/HDL-cholesterol being associated with a 27% decrease in the risk of haemorrhagic stroke. In conclusion, whilst increases in HDL-cholesterol and decreases in TC relative to HDL-cholesterol were beneficial for CHD, no evidence of an association between either HDL-cholesterol or TC/HDL-cholesterol and ischaemic stroke were found. The authors suggest that stroke subtypes should be considered separately regarding the effects of lipoproteins.
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