Background: In the "fourth stage" of epidemiological transition, the distribution of non-communicable diseases is expected to shift to more advanced ages, but age-specific changes beyond 80 years of age have not been reported.
Methods: This study aimed to evaluate demographic and health transitions in a population aged 80 years and over in the United Kingdom from 1990 to 2014, using primary care electronic health records. Epidemiological analysis of chronic morbidities and age-related impairments included a cohort of 299,495 participants, with stratified sampling by five-year age group up to 100 years and over. Cause-specific proportional hazards models were used to estimate hazard ratios for incidence rates over time.
Results: Between 1990 and 2014, nonagenarians and centenarians increased as a proportion of the over-80 population, as did the male-to-female ratio among individuals aged 80 to 95 years. A lower risk of coronary heart disease (HR 0.54, 95% confidence interval [CI]: 0.50-0.58), stroke (0.83, 0.76-0.90) and chronic obstructive pulmonary disease (0.59, 0.54-0.64) was observed among 80-84 year-olds in 2010-2014 compared to 1995-1999. By contrast, the risk of type II diabetes (2.18, 1.96-2.42), cancer (1.52, 1.43-1.61), dementia (2.94, 2.70-3.21), cognitive impairment (5.57, 5.01-6.20), and musculoskeletal pain (1.26, 1.21-1.32) was greater in 2010-2014 compared to 1995-1999.
Conclusions: Redistribution of the over-80 population to older ages, and declining age-specific incidence of cardiovascular and respiratory diseases in over-80s, are consistent with the "fourth stage" of epidemiologic transition, but increases in diabetes, cancer, and age-related impairment show new emerging epidemiological patterns in the senior elderly.
Keywords: Chronic disease; Epidemiological transition; Epidemiology; Incidence; Morbidity; Primary care; Senior elderly; UK; Very old.