Season, temperature and blood pressure: a complex interaction.

An increase in blood pressure values measured during winter either in the office, at home, or at ambulatory blood pressure monitoring was consistently observed. Besides potentially contributing to increase the risk for cardiovascular events during the cold season, long term blood pressure variations can influence results of clinical trials, epidemiological surveys, and require personalized management of antihypertensive medications in the single patient. Those variations are often considered as an effect of climate, due to the close correlation observed in various countries and in different settings between temperature and blood pressure among children, adults, and specially the elderly. However, obtaining true measurements of exposition is a main problem when investigating the effects of climate on human health especially when the aim is to disentangle the effects of climate from those of seasonality. The aim of the present note is not to provide a complete review of the literature demonstrating the implications of seasonal blood pressure changes in the clinical and experimental setting; rather it is to consider methodological aspects useful to investigate the interaction between seasonality and temperature on blood pressure and to make health care providers aware of the implications of environmental factors on blood pressure in clinical and research settings.