Socio-demographic differences in the onset and progression of disability in early old age: a longitudinal study

Objectives: to analyse socio-demographic differences in the onset and progression of disability. Design: analysis of a cohort of people aged 55-69 in 1988-9 and in 1994. Subjects: a representative sample of 3543 adults. Methods: we measured severity of disability at baseline and follow-up. We analysed variations in incidence and progression of disability by using logistic regression. Results: Baseline severity of disability was similar for men and women but varied by age group, social class, educational qualifications and housing tenure. At follow-up, 36% had worse disability, 12% better and 53% the same as at baseline. Increased severity of disability and new incidence of disability were associated with lower socioeconomic status, baseline self-rated health status, age and gender. High initial levels of disability were associated with improvement at follow-up. Conclusion: disability can be dynamic, although deterioration is more usual than improvement. The reasons for the associations found between disability and socioeconomic status are unclear.