THE CROSS-SECTIONAL AND LONGITUDINAL ASSOCIATIONS BETWEEN HOME ENERGY EFFICIENCY AND HYPERTENSION

Objective: Indoor temperature is a wider determinant of hypertension, but the relationship between hypertension and policy-relevant measures affecting the indoor temperature is unclear. Our study aimed to determine the associations between home energy efficiency and hypertension in a large cohort of adults living in Wales. Design and method: We performed a population-level retrospective study using data available via the Wales-wide Secure Anonymised Information Linkage (SAIL) Databank. Energy Performance Certificate (EPC), Welsh Demographic Service, GP and 2021 Census datasets were cleaned and linked. The study population included all adults recorded as living in Wales, having a valid EPC and registered at a GP providing data to SAIL as of 21/3/2021, and with 2021 Census data linked. The exposure variables studied were wall insulation presence/type and EPC rating (a proxy for household-level energy efficiency), and the outcome was first GP-coded diagnosis of hypertension. Covariates were: age, sex, education level, employment status, heating type, window type, building age, building size, tenure type, urban/rural category and deprivation score. An initial cross-sectional study (outcome being first diagnosis prior to 21/3/2021) was performed with multivariate logistic regression, with survival analyses performed with Cox regression for this address period, after excluding those previously diagnosed. Results: 835812 people were included in the cross-sectional analysis, and from this cohort, 712569 were included in longitudinal analysis, with a median (IQR) follow-up time of 48 (29-81) months. Cavity wall insulation was associated with a significantly lower odds of having hypertension in the cross-sectional analysis, but this was not statistically significant in the longitudinal analysis. Aggregate energy efficiency ratings did not show statistically significant associations with the odds or hazard ratios for hypertension (Table 1). In both analyses, important confounders were identified as age, sex, education level, employment, deprivation and rural/urban category.Conclusions: Neither wall insulation type or aggregate energy efficiency ratings showed a clear association with hypertension in fully-adjusted analyses, counter to our expectations given blood pressure’s established relationship with indoor temperatures. Limitations include unrepresentative EPC coverage, and undiagnosed hypertension varying differentially with energy efficiency. Further research should investigate how specific energy efficiency measures influence indoor temperatures.