Orthostatic hypotension in patients with Alzheimer's disease: a meta-analysis of prospective studies.

Background Orthostatic hypotension (OH) is a clinical sign associated with severe adverse health outcomes in older adults. It has been reported to be common in patients with Alzheimer's disease (AD). The present meta-analysis aimed to investigate the prevalence and risk of OH in AD patients. Methods English-language articles published from January 1990 to August 2020 were searched in PubMed, ScienceDirect, Cochrane, and Web of Science with the keywords "Alzheimer" and "autonomic dysfunction" or "dysautonomia" or "postural hypotension" or "orthostatic hypotension." All prospective clinical studies (case-control, cohort, and cross-sectional studies, and randomized controlled trials) that were regarded as pertinent were included in this study. For quality assessment, the Newcastle-Ottawa Scale was used. Odds ratios (OR) and risk ratios (RR) were extracted with 95% confidence intervals (CI) and combined using the random effects model after logarithmic transformation. The prevalence in the AD patients was also combined using the random effects model. Results The meta-analysis involved 11 studies (7 case-control and 4 case series) to assess the risk of OH in AD. It was found that AD increased the risk of OH with an RR of 1.98 (95% CI: 0.97-4.04) and an OR of 2.53 (95% CI:1.10-5.86) compared to healthy controls, and OH was present in 28% (95% CI: 0.17-0.40) of 500 AD patients. Conclusion There is an elevated risk of OH in AD by nearly 2.5-fold. Therefore, the evaluation of postural blood pressure changes should definitely be among the follow-up and treatment goals of AD