Rurality, deprivation, and excess winter mortality: an ecological study.

The reasons for the higher levels of excess winter mortality in Britain, compared with countries with colder winters, are unclear. Ecological studies suggest that both increased outdoor and indoor cold exposure relating to poor housing energy efficiency and lack of adequate clothing and physical activity when outdoors are important. 2 It seems plausible that excess winter mortality would be greater in more deprived areas as deprived populations are more likely to live in poor quality energy inefficient housing and are less likely to be car owners. Two British studies have found no association between area deprivation and excess winter mortality, but both were based in single district health authorities and may not have had the power to detect an association. 4 Furthermore, both studies were based in urban areas and were unable to assess the association between excess winter mortality and rurality. It has been suggested that rural areas in Britain are at increased risk of excess winter mortality and that government action should be targeted at these areas. A range of features— poor quality housing, high proportion of detached houses, lack of access to gas networks, and low take up of government energy efficiency grants—may make rural populations vulnerable to indoor cold exposure. Outdoor occupations and poor public transport systems in rural areas may increase outdoor cold exposure. The aim of this study was to assess the association between both rurality, and area deprivation, and excess winter mortality in a large region of England with a population of nearly six million and a distribution of both urban and rural areas. METHODS AND RESULTS The age sex standardised seasonality ratio was calculated for each ward of the South West Region using data aggregated over a five year period 1994–1998. Mortality data by month were obtained from the Office of National Statistics and population data were calculated by linearly projecting between the under-enumeration adjusted 1991 census population estimates and the mid-1996 estimates. Rates were standardised, using the direct method of standardisation, to the WHO European standard population. Confidence intervals for seasonality ratios were calculated using Breslow-Day’s method. Population density, a measure of rurality, and Townsend deprivation scores were calculated for each ward using small area statistics data from the 1991 census. Both seasonality ratios and Townsend deprivation scores were normally distributed across the wards. Population density was approximately log normal. Pearson’s correlation coefficients and partial coefficients were used to assess the associations between the log of population density and seasonality ratios and between Townsend deprivation scores and seasonality ratios. Over the five year period of the study 279 513 deaths in total occurred with 54 681 deaths in 1994 (the smallest number) and 56 262 in 1997 (the year with the highest number of deaths). The associations between deprivation and rurality and excess winter mortality were assessed across 1169 wards and we had 85% power to detect a correlation at the 5% level of significance. Neither population density nor Townsend deprivation scores were associated with excess winter mortality (table 1). Pearson’s correlation coefficient (95% confidence intervals) for