Accuracy of death certificates for recording parkinsonian syndromes and associated dementia

Introduction
Death certification is often used to identify patients with certain diseases in epidemiologic research. There have been few studies looking at the accuracy of recording of parkinsonian diagnoses, any associated dementia and the cause of death on death certificates in people with parkinsonian conditions. This study aimed to assess this.

Methods
Data for these analyses were derived from a prospective incident cohort of degenerative/vascular parkinsonian syndromes with lifelong follow-up from Scotland, UK (the PINE study). In those who died, the available research and clinical care records were reviewed to establish the cause for each patient’s death. The sensitivity of death certificates was calculated to detect any parkinsonian diagnosis mentioned on the death certificate, the correct specific diagnosis and the presence of dementia. The causes of death were compared between clinical records and death certificates.

Results
Two hundred and seventy-seven patients had died (180 men), mean age at diagnosis and death 76.9 years and 81.9 years respectively. 66.8% of death certificates mentioned any parkinsonian syndrome but only 49.5% had the correct diagnosis. Sensitivity was highest for Parkinson’s disease, those who had parkinsonian-related deaths, had longer disease durations and died out of hospital. Death certificates detected 51.2% of those with dementia. The commonest causes of death were pneumonia, end-stage Parkinsonism and vascular disease with moderate agreement between case-note review and death certification.

Conclusion
Deaths certificates often do not mention underlying Parkinsonism or associated dementia and so epidemiological studies should not rely on this as a sole method of identifying cases or studying mortality.