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Deaths in collective dwellings and inequalities in small-area mortality: an ecological study in the Madrid region (Spain)
  1. A Gandarillas1,
  2. M F Domínguez-Berjón1,
  3. B Zorrilla1,
  4. I Galán1,
  5. I Duque2,
  6. J Segura del Pozo1
  1. 1Directorate-General for Public Health, Madrid Regional Health Authority, Madrid, Spain
  2. 2Subdirectorate-General for Population, Immigration Statistics (National Statistics Institute), Madrid, Spain
  1. Correspondence to Dr Ana Gandarillas, Servicio de Epidemiología, Subdirección de Promoción de la Salud y Prevención, Dirección General de Atención Primaria, Consejería de Sanidad. Comunidad de Madrid, C/Julián Camarillo, 4b, 2a planta, Madrid 28037, Spain; ana.gandarillas{at}


Background Increasing numbers of elderly persons reside and die in institutions, yet there are few studies that analyse the effect of this on mortality in small areas and its ensuing effect on the association between material deprivation and mortality.

Methods A cross-sectional, ecological study in the region of Madrid covering 3906 census tracts (median 1000 inhabitants), using mortality data for 1996–2003 and socioeconomic deprivation from the 2001 census. Standardised mortality ratios (SMR) were calculated for each census tract. Using the Besag–York–Mollié model, RR of dying and their 95% CI according to the deprivation index considered (with the fourth quartile, Q, being the most unfavourable situation) were calculated for deaths among: the total population and the population excluding residents who died in institutions.

Results 6% of the deceased had been residing in institutions, which affected 16.5% of census sections (644) and accounted for 17% of the variability in SMR among men and 10% among women, p<0.001. Mortality increased with socioeconomic deprivation, whereas the RR for the total population in Q4 with respect to Q1 was 1.46 among men (95% CI 1.41 to 1.50) and 1.12 among women (95% CI 1.08 to 1.17), these figures rose to 1.48 (95% CI 1.43 to 1.53) and 1.14 (95% CI 1.10 to 1.18), respectively, for the population excluding residents who died in institutions.

Conclusions Deaths of residents in institutions affect the variation in small-area mortality, and confound the relationship between mortality and socioeconomic deprivation. This variable should be recorded in mortality statistics so that its effect can be controlled for in subsequent analyses.

  • Ageing RB
  • collective dwellings
  • inequalities SI
  • mortality SI
  • small-area analysis
  • small area SI
  • socioeconomic factors
  • spatial analysis

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  • Funding This study formed part of the MEDEA project (Mortality in small areas in Spain, and socio-economic and environmental inequalities), and was funded by the Ministry of Health and Consumer Affairs, Spain (FIS: PI040069).

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.