Background:
Cardiovascular disease (CVD) and dementia have profound impacts on the morbidity and disability burden in older people. Uncertainty remains regarding the future incidence of these conditions. We forecast future levels of morbidity and disability in England and Wales up to 2040 under two scenarios regarding CVD and dementia future trends.
Methods:
We developed a probabilistic Markov model (IMPACT-BAM) which follows the transitions of the England and Wales population into health states characterised by the presence or absence of CVD, dementia and disability to 2040. Data sources include national health registers (ONS) and cohort studies (HSE, Whitehall II and ELSA). Modelled CVD and Non-CVD mortality and prevalence trends for disability and morbidity were used to estimate trends in life expectancy (LE), morbidity-free life expectancy (MFLE) and disability-free life expectancy (DFLE). We assumed that CVD incidence and mortality will continue their current trends and modelled two scenarios: Scenario A assumes constant dementia incidence, a common assumption when projecting future burden of dementia; Scenario B assumes 2% annual decline in dementia incidence, as suggested in UK population-based cohorts.
Results:
In 2011, LE at age 65 was 18.4 years for men and 21.0 years for women. In Scenario A, LE at 65 in 2040 will increase to 26.7 and 24.8 years in men and women. DFLE at 65 will increase (by 5.5 years in men and 2.8 years in women, to 21.7 and 20.7 years respectively). MFLE at 65 will increase slightly (by 1.5 years in men and 1.4 in women, to 10.7 and 13.2 years respectively). Disability prevalence would increase by 3.1% to 14.4% ( 1,081,483 of 7,510,299) in men and decrease slightly (by 0.6% to 14% (1,214,754 of 8,676,813)) in women. In Scenario B, LE at 65 in 2040 will increase to a similar degree as in Scenario A, but DFLE and MFLE will increase faster (DFLE: by 7.5 years in men and 4.6 in women, to 23.7 and 22.5 years respectively; MFLE: by 4.5 years for both genders to 13.8 years in men and 16.3 in women). Disability prevalence will slightly increase (by 0.8% to 12.1% (908,746 of 7,510,299)) in men and decrease by 3.0% to 11.4% (989,157 of 8,676,813) in women.
Conclusions:
The future disability burden crucially depends on assumptions about future dementia incidence trends. If the dementia incidence continues unchanged, the duration of morbidity and disability will be prolonged. However, if dementia incidence decreases (as suggested in the UK and mirroring CVD declines) we could live more years in good health, with morbidity compressed into a shorter period before death.
The future of life expectancy and life expectancy inequalities in England and Wales: Bayesian spatiotemporal forecasting