Mortality in Parkinson's disease: A systematic review and meta-analysis

Authors


  • Funding agencies: This study was supported by the Chief Scientist Office of the Scottish Government (Clinical Academic Fellowship CAF/12/05) and the University of Aberdeen.

  • Relevant conflicts of interest/financial disclosures: Dr. Macleod is funded by a Clinical Academic Fellowship from the Scottish Chief Scientist Office. Dr. Taylor received funding from the University of Aberdeen to carry out the research related to this manuscript. Dr. Counsell reports no financial disclosures relating to the research covered in the manuscript. We declare we have no conflicts of interest.

  • Full financial disclosures and author roles may be found in the online version of this article.

Abstract

This study was undertaken to perform a systematic review and meta-analysis of studies of mortality in Parkinson's disease (PD) and to investigate which factors were associated with mortality. We conducted comprehensive searches of studies reporting a ratio of mortality in PD versus controls, descriptive survival measures, or factors predicting survival; assessed study quality; and extracted relevant data. Descriptive analysis, meta-analysis, and meta-regression were performed as appropriate. Eighty-eight studies were included in the review with variable study methods and quality. Almost all studies reported increased mortality in PD (vs. controls), with mortality ratios ranging from 0.9 to 3.8, with major between-study heterogeneity. Inception cohorts were more consistent with a pooled mortality ratio of approximately 1.5. Inception cohorts, measurements at longer follow-up duration, and older study recruitment year were associated with lower mortality ratios, but these findings were not robust in sensitivity analyses. Within studies, mortality ratios increased over time. No robust evidence was found that mortality has decreased after the introduction of levodopa (L-dopa). On average, PD survival reduced by approximately 5% every year of follow-up, although there was significant heterogeneity. In post-mortem studies, mean duration until death ranged from 6.9 to 14.3 years. Increasing age and presence of dementia were most commonly associated with increased mortality. Parkinson's disease is associated with increased mortality, but major heterogeneity is seen in estimates of mortality, which is probably explained by variable methodology and patient selection. Individual-patient-data meta-analysis of high-quality inception studies with long-term follow-up would be the optimal way to investigate the factors influencing mortality. © 2014 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

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