Local population differences and the needs of people with cognitive impairment.
Variations in local population age structure have attracted less attention than national population ageing. As moderate and severe cognitive impairment is a major cause of need for long-term care, population-based estimates of the numbers and characteristics of this group were calculated, to explore the effects of local differences. The UK Office of Population Census and Surveys (OPCS) study of disability in adults (N > 14000) was reanalysed. A group with moderate or severe cognitive impairments was identified and age-specific estimators of sociodemographic characteristics, household types, disabilities and service use were combined with population estimates for district health authorities in England and Wales. The proportion of the 65 plus population who are 85 plus varies from 8% to 15% across districts, equivalent to national population projections for 1986 and 2031 respectively. The estimated prevalence of the study group varies from 53 to 70 per 1000 population aged 65 plus, with 34-48% of cases aged 85 plus. Curiously, the proportion with severe disabilities varies little across districts. If national norms applied, local rates of institutionalization would vary from 18 to 27 per 1000 aged 65 plus. Local differences in population age structure age large compared to national changes over decades. Local differences have substantial effects on overall prevalence and on the proportion of the cognitively impaired who would be institutionalized if national patterns applied. Service design should be influenced by these complex variations, with estimates modified by local surveys.