Relationship between outdoor temperature and cardiovascular disease risk factors in older people.

Background Previous studies demonstrated that lower outdoor temperatures increase the levels of established cardiovascular disease risk factors, such as blood pressure and lipids. Whether or not low temperatures increase novel cardiovascular disease risk factors levels is not well studied. The aim was to investigate associations of outdoor temperature with a comprehensive range of established and novel cardiovascular disease risk factors in two large Northern European studies of older adults, in whom cardiovascular disease risk is increased. Design and methods Data came from the British Regional Heart Study (4252 men aged 60-79 years) and the Prospective Study of Pravastatin in the Elderly at Risk (5804 men and women aged 70-82 years). Associations between outdoor temperature and cardiovascular disease risk factors were quantified in each study and then pooled using a random effects model. Results With a 5℃ lower mean temperature, total cholesterol was 0.04 mmol/l (95% confidence interval (CI) 0.02-0.07) higher, low density lipoprotein cholesterol was 0.02 mmol/l (95% CI 0.01-0.05) higher and SBP was 1.12 mm Hg (95% CI 0.60-1.64) higher. Among novel cardiovascular disease risk factors, C-reactive protein was 3.3% (95% CI 1.0-5.6%) higher, interleukin-6 was 2.7% (95% CI 1.1-4.3%) higher, and vitamin D was 11.2% (95% CI 1.0-20.4%) lower. Conclusions Lower outdoor temperature was associated with adverse effects on cholesterol, blood pressure, circulating inflammatory markers, and vitamin D in two older populations. Public health approaches to protect the elderly against low temperatures could help in reducing the levels of several cardiovascular disease risk factors.