ReviewPrevalence of orthostatic hypotension in Parkinson’s disease: A systematic review and meta-analysis
Introduction
In advanced Parkinson’s disease (PD), non-motor symptoms may be the major determinant of disability [1]. Orthostatic hypotension (OH) is one of the non-motor features in PD. It is thought to be the result of degeneration of the peripheral autonomic nervous system as part of the disease progress [2]. These abnormalities lead to an inadequate response to the gravitational force on the effective circulatory volume during standing due to defective vasoconstriction and excess venous pooling of blood [3]. Symptoms of OH mainly result from cerebral and retinal hypoperfusion and include dizziness, faintness, seeing black spots, and may even be accompanied by a transient loss of consciousness [4]. The occurrence of symptoms is directly related to the extent of the blood pressure drop, but autoregulation of the cerebral vasculature and baseline supine blood pressure probably also play a role. This hypothesis is supported by data showing that about one-third of patients with a systolic blood pressure drop of 60 mmHg or more during tilt-table testing are completely asymptomatic during the test [5].
By consensus, OH has been defined as a fall of ≥20 mmHg systolic or ≥10 mmHg diastolic blood pressure by 3 min of active standing or head up tilt [6]. Recently, the consensus-statement has been revised and a systolic fall of 30 mmHg was suggested for patients with an abnormally high supine blood pressure [7]. OH can be a debilitating problem and an association with increased mortality was shown for the general population [8]. Over recent decades, awareness of the impact of OH in PD has increased and consequently more research on this topic has come available. Furthermore, comprehensive reviews have been published concerning pathophysiology, diagnosis, and management of OH in PD [2], [9]. Despite the increasing amount of research concerning this subject, the prevalence of OH in PD stated in the literature has a wide range; i.e., 10–58% [10], [11], [12]. Accordingly, we conducted a systematic review of the literature in order to estimate the prevalence of OH in PD more precisely.
Section snippets
Literature search
We searched the electronic databases Medline and Embase using the entire time scale up to December 2009. The terms “Parkinson’s disease”, “Parkinson disease”, and “parkinsonism” were combined with “orthostatic hypotension” and “orthostatic intolerance”. The full search strategy is available in the Data supplement.
Study selection
After combining the search results, a list of titles and abstracts was evaluated by two independent reviewers (DCV and RMAdB) for eligible studies. Studies were selected according to
Literature search and study selection
Combining both the lists of titles and abstracts resulted in 836 records. Fig. 1 shows the results of the search and the study selection. A total of 80 full-text articles were selected for further review. Of these, 25 fulfilled our selection criteria. The other 55 articles were excluded for the following reasons: 33 studies reported a mean change of blood pressure after standing for the total patient group instead of the number of patients with OH; 8 studies used the presence or absence of
Discussion
This is the first systematic review investigating the prevalence of OH in PD. The prevalence we found lies in the range stated in previous non-systematic reviews concerning this subject. We found a large heterogeneity between studies. In addition, repeated analyses for several subgroups of studies with specific characteristics—e.g., sample size above 70, less risk for selection bias—also showed large heterogeneity between studies.
Though there was a large variety between studies, this is the
Acknowledgments
This study is funded by the Prinses Beatrix Fonds, the Hague, The Netherlands
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