How cold waves influence LDL cholesterol levels? A regional study for Campinas, Sao Paulo, Brazil

The increase in deaths from cardiovascular diseases in extreme temperature events, particularly during cold waves, is a phenomenon already reported in the literature. One of its mechanisms is the increased likelihood of atherosclerotic plaque formation due to higher concentrations of low-density lipoprotein cholesterol (LDL-c) in the blood at periods of lower temperatures. This study adopts a data science approach to check evidence of this mechanism in a sample population of Campinas, a city in the southeast region of Brazil, with over 1 million inhabitants. We integrated climate and health datasets and processed over 1,677,424 LDL-c exam results combined with minimum and maximum daily air temperature data in the city in eleven years (2008-2018). The data were stratified into sex and age groups, and we analyzed the difference in distributions of LDL-c levels for those exposed to cold waves versus control days. We also analyzed differences in the distributions up to ten days (lags) after an exposure. Cold waves were defined as at least three consecutive days with minimum and maximum temperatures below their 10th percentiles, considering a 30-year climate normal (1961-1990). In particular, we analyzed the effect of cold waves on LDL-c levels above the reference value. Our analyses identified nine cold waves in the period and statistically relevant effects on exam results. The amount LDL-c exams with levels above reference value were 3.32% greater for women between 20 and 65 years old (lag 2), 9.27%, 7.39%, and 4.06% for women over 65 (lags 0, 2, and 7, respectively), and 11.45% for men over 65 (lag 4).