The association between antidepressant use and orthostatic hypotension in older people: a matched cohort study

Abstract

Orthostatic hypotension (OH) is often reported as a significant potential adverse effect of antidepressant use but the association between phasic blood pressure (BP) and antidepressants has not yet been investigated. This cross-sectional study compares continuously measured phasic BP and prevalence of OH in a cohort of antidepressant users ≥50 years compared with an age- and sex-matched cohort not taking antidepressants. OH was defined as a drop in systolic BP ≥ 20 mm Hg or in diastolic BP ≥ 10 mm Hg at 30 seconds after standing, measured using continuous beat-to-beat finometry. Multilevel time × group interactions revealed significantly greater systolic and diastolic BP drop in antidepressant users than nonusers at 30 seconds after stand. The prevalence of OH among antidepressant users was 31% (63/206), compared with 17% in nonusers (X² = 9.7; P = .002). Unadjusted logistic regression models demonstrated that selective serotonin reuptake inhibitor use was associated with OH at an odds ratio of 2.11 (95% confidence interval: 1.25–3.57); P = .005, and this association was not attenuated when covariates including cardiac disease and depressive symptom burden were added. There was no statistically significant association between serotonin noradrenaline reuptake inhibitor or tricyclic antidepressant use and OH in unadjusted models although the study was not powered to detect changes within these subgroups. Older people taking antidepressants have a two-fold higher prevalence of OH than nonusers, highlighting the importance of screening the older antidepressant user for OH and dizziness and rationalizing medications to reduce the risk of falls within this vulnerable cohort.

Introduction

Antidepressant therapy is efficacious for depression in older people¹ but there are concerns regarding adverse effects, particularly in a frail, older population.²

Given the vascular basis of depression in later life,³ as well as the association between depression and falls,⁴ orthostatic hypotension (OH) is a significant potential adverse effect of antidepressant therapy.⁵

OH is common in older people and is defined as a drop in systolic blood pressure (BP) by at least 20 mm Hg or diastolic BP by at least 10 mm Hg within 3 minutes of standing.⁶ OH often coexists with depression in later life⁷ and is associated with falls and syncope, as well as cardiovascular disease and an increased all-cause mortality risk.8, 9 For diagnosis of OH, clinical practice has generally shifted toward increasing use of continuous orthostatic BP measurement rather than sphygmomanometer-based readings as this allows real-time tracking of BP,¹⁰ capturing dynamic BP shifts that are missed by other techniques.¹¹

Antidepressants in general are often listed as one of the drugs exacerbating OH.⁵ However, despite the reported association between antidepressants and OH, there has been relatively limited research to date examining their impact on continuously measured orthostatic BP. The aim of this study therefore was to estimate the association of antidepressant use with OH, defined using phasic BP technology, and clarify the strength of association of regularly prescribed antidepressants with OH in a cohort of community-dwelling older people.