Four decades of regional climate exposure and adult blood pressure in the Northern Finland Birth Cohort 1966

Climate exposures have been associated with cardiovascular health, but most studies focus on short-term exposure and individual climate parameters. This study explored the use of longitudinal multidimensional clustering in studying climate exposures over the life-course, in relation to adult blood pressure (BP). Annual averages of seven climate exposures were linked to the residential coordinates of the Northern Finland Birth Cohort 1966 (n = 4,225). Individual climate trajectories were grouped by a non-parametric algorithm for clustering joint trajectories (kml3d) across youth (4-24y) and adulthood (25-46y). Generalized linear models were used to assess the relationship between climate clusters and clinically measured systolic BP (SBP) and diastolic BP (DBP) at 46 years, adjusting for relevant confounders. Two youth clusters (A and B) were identified, while three clusters (A, B and C) emerged in adulthood. Compared to cluster A, the reference at both stages, B describes a colder northern climate, while C represents a transition to a warmer southern climate. Results show that growing up in the coldest climate (B) was associated with lower SBP (−1.13 mmHg, 95%CI −2.21, −0.05). Adult exposure to the warmest southern climate (C) was associated with lower SBP (−4.17 mmHg, 95%CI −5.38, −2.97) and DBP (−1.90 mmHg, 95%CI −2.72, −1.08). Youth and adult climate exposures were independently associated with adult BP. Future studies should assess to which extent health inequality plays a role. Our results show that kml3d clustering can identify distinct regional climates, facilitating observational studies on climate exposure.