Effect of cold temperatures on mortality in Cantabria (Northern Spain): a case-crossover study

Objectives: To determine the impact of low temperatures on mortality in a Spanish region that includes both rural and urban areas.

Study design: Case-crossover study.

Methods: A case-crossover study was conducted on the impact of cold temperatures on mortality in Cantabria, a Spanish region which includes both rural and urban areas, in 2004-2005. Odds ratios for several cold weather indicators were estimated using conditional logistic regression, adjusting for humidity and wind speed. Zero- to 6-day lags in the temperature effect were considered.

Results: Temperatures lower than the 5th percentile were strongly associated with mortality compared with temperatures above the 5th percentile (OR 3.40, 95% confidence interval 2.95-3.93 for 6-day lag). All temperature indices show a negative association with mortality; for instance, the maximum temperature had ORs of 0.71, 0.58, 0.32 and 0.16 for Quintiles 2-5 (reference: Quintile 1). This effect was common to all age groups.

Conclusion: Cold weather is strongly associated with mortality in small cities and rural areas.