Relative survival in patients with dementia with Lewy bodies and Parkinson’s disease dementia

INTRODUCTION: The understanding of survival in dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD) is limited, as well as the impact of these diagnoses in an ageing co-morbid population. METHODS: A retrospective study of 177 patients who received a DLB or PDD diagnosis between 1997–2014 at the Memory Clinic in Malmö, Sweden. Relative survival was evaluated by adjusting all-cause survival for expected survival, estimated from population life-tables, matched by sex, age and calendar year. Predictors of relative survival were investigated using multivariate regression modelling. RESULTS: At follow-up, 143 (81%) patients were deceased with a median survival of 4.1 years (IQR 2.6–6.0). After 10-years follow-up, the standardized mortality ratio was 3.44 (95% CI 2.92–4.04). Relative survival was worse with younger age at diagnosis (excess hazard ratio [eHR] 0.91, 95% CI 0.88–0.94 per year of age), female sex (eHR 1.45, 95% CI 1.01–2.09) and lower mini-mental state examination (eHR 0.93, 95% CI 0.90–0.96). Subgroup analysis (n = 141) showed higher mortality in DLB patients who were positive for APOE ɛ4 (eHR 2.00, 95% CI 1.35–2.97). CONCLUSION: The mortality is over three-times higher in patients diagnosed with dementia with Lewy bodies and Parkinson’s disease dementia during a ten-year follow-up, compared to persons in the general population. Excess mortality is found primarily in younger patients, females and carriers of APOE ε4. Further research is needed regarding survival and possible interventions, including disease-modifying treatments, to improve care for this patient group.