Hypovitaminosis D and orthostatic hypotension: A systematic review and meta-analysis

Orthostatic hypotension is a common condition among older adults and is associated with a range of deleterious outcomes. Recently, interest has developed in hypovitaminosis D (defined as low 25 hydroxiyvitamin D levels) as a potential risk factor for orthostatic hypotension. We conducted a systematic review and meta-analysis examining the association of orthostatic hypotension between study participants with and without hypovitaminosis D, including the adjustment of potential confounders (age, sex, BMI, renal function, comorbidities, seasonality, use of antihypertensive medications, and supplementation with cholecalciferol). A systematic literature search of major electronic databases from inception until 09/2015 was made for articles providing data on orthostatic hypotension and hypovitaminosis D. A random effects meta-analysis of cross-sectional studies investigating orthostatic hypotension prevalence comparing participants with vs. those without hypovitaminosis D was undertaken, calculating the odds ratios (ORs) and 95% confidence intervals (CIs). Of 317 initial hits, five cross-sectional studies were meta-analysed including 3646 participants (1270 with hypovitaminosis D and 2376 without). The participants with hypovitaminosis D had a higher prevalence of orthostatic hypotension (OR = 1.88; 95% CI: 1.25-2.84; I-2 = 68%) that was not affected by adjusting for a median of five potential confounders (OR - 2.03; 95% CI: 1.13-3.68; I-2 = 73%). People with orthostatic hypotension had significantly reduced serum vitamin D concentrations (standardized mean difference = -0.42; 95% CI: -0.72 to -0.12). One longitudinal study confirmed the association between hypovitaminosis D and orthostatic hypotension. Our meta-analysis highlights that hypovitaminosis D is associated with orthostatic hypotension, independent of potential confounders. Further longitudinal studies and clinical trials are required to confirm these findings.