Effective interventions for potentially modifiable late-onset dementia risk factors: a costs and cost-effectiveness modelling study

Background The potential economic value of interventions to prevent late-onset dementia is unknown. We modelled this for potentially modifiable dementia risk factors. Methods We searched PubMed and Web of Science from inception to March 2020 and included interventions that (a) successfully targeted any of nine pre-specified potentially modifiable risk factors (hypertension, diabetes, hearing loss, obesity, physical inactivity, social isolation, depression, cigarette smoking and less childhood education), (b) had robust evidence that the intervention improved risk or risk behaviour and (c) are feasible in an adult population. We established when in the life-course each intervention would be delivered. We calculated dementia incidence reduction from: annual incidence of dementia in people with each risk factor; population attributable fraction for each risk, corrected for risk factor clustering, and how effectively the intervention controls the risk factor. We calculated the discounted value of lifetime health gain and impact on cost (including NHS, social care and carer costs) per person eligible for treatment. We estimated annual total expenditure on the fully operational intervention programme in England. Findings We found effective treatments for hypertension, stopping smoking, diabetes prevention and hearing loss. Treatments for stopping smoking and provision of hearing aids reduced cost. Treatment of hypertension was cost-effective by reference to standard UK thresholds. The three interventions when fully implemented would save £1·863 billion annually in England, reduce dementia prevalence by 8·5% and produce QALY gains. The intervention for diabetes was unlikely to be cost-effective in terms of impact on dementia alone. Interpretation There is a strong case for implementing the three effective interventions on grounds of cost-effectiveness and quality of life gains, as well as for improvements in general health. There is considerable room for the interventions to remain cost-saving or cost-effective even with variations in dementia incidence and costs and effectiveness of interventions