Impact of energy efficiency interventions in public housing buildings on cold-related mortality: A case-crossover analysis

Background: Interventions to mitigate fuel poverty and particularly energy efficiency façade retrofitting (EEFR) have demonstrated positive impacts on health but the impacts of EEFR interventions on cold-related mortality have not been studied in depth. We evaluated the impact of EEFR interventions in Barcelona on the association between cold outdoor temperatures and mortality (from all natural causes and from neoplasms, circulatory system and respiratory system causes) from 1986 to 2012. Methods: A time-stratified case-crossover analysis was used. Relative risks (RR) for death related to extreme cold (lowest fifth percentile) in the no-intervention and intervention groups were obtained for temperature lag windows covering the day of the death and the previous 20 days (0-2, 3-5, 6-8, 9-11, 12-14, 15-17, 18-20). The statistical significance of the observed changes was evaluated using the RR for the cold temperature-intervention interaction. Results: In men, interventions significantly increased the extreme cold-death association for the lag window 15-17 [interaction RR 2.23, 95% confidence interval (CI) 1.14-4.36]. The impacts were stronger for respiratory system causes and in men aged 75 or older. In women, on lag window 0-2, the extreme cold-death association was not significantly reduced when analysing all natural causes of death (interaction RR 0.46, 95% CI 0.21-1.01), but it was reduced significantly when analysing only deaths from neoplasms, circulatory system and respiratory system causes together. The impacts were stronger in women who died from circulatory system causes, in women with no education and in those aged 75 or older. Conclusions: EEFR interventions had differentiated effects on cold-related mortality in men and women. Differentiated effects were also observed by cause, educational level and age.