Hypertension and Risk of Post-Operative Cognitive Dysfunction (POCD): A Systematic Review and Meta-Analysis

Abstract

Background:Post-operative cognitive dysfunction (POCD) occurs frequently after major surgery. Hypertension is well-established as a risk factor for age-related cognitive impairment, but it is unclear whether or not it also increases the risk of POCD.Objective:To evaluate the role of hypertension in POCD risk in a systematic review and meta-analysis.Method:PubMed, Ovid SP and the Cochrane Database of Systematic Reviews were searched for longitudinal studies of adults undergoing surgery with reporting of hypertension, blood pressure and/or anti-hypertensive treatment associations with POCD as relative risks or odds ratios. Fixed-effects meta-analyses were performed using Review Manager (version 5.3).Results:Twenty-four studies on 4317 patients (mean age 63 years) were included. None of the studies had set out to assess hypertension as a risk factor for POCD. Hypertension was used as a categorical predictor throughout and only 2 studies adjusted for potential confounders. Across all 24 studies, hypertension was not significantly associated with POCD risk (RR 1.01; 95% CI 0.93, 1.09; p=0.82), though among 8 studies with >75% males, we found hypertension associations with a 27% increased risk of POCD (RR 1.27, 95% CI 1.07, 1.49; p=0.005).Conclusion:Our findings do not support the hypothesis that hypertension is a risk factor for POCD. However, since none of the studies included in our analysis were hypothesis-driven and most did not adjust for potential confounders, further systematic investigations are needed to evaluate the role of hypertension in the epidemiology of POCD.

Diabetes, but Not Hypertension and Obesity, Is Associated with Postoperative Cognitive Dysfunction

“…Hypertension and obesity were not independently associated with risk of POCD. These findings extend our previous meta-analyses which, largely based on unadjusted results of exploratory studies, had found significant associations for diabetes but not for obesity or hypertension with POCD risk [7, 8, 10]. …”

“…However, we did not see any significant influence of a prior history of hypertension on risk of POCD that was independent of its link to diabetes. The null finding suggests that vascular damage as a consequence of hypertension may only play a minor role in POCD development and replicates results of our meta-analysis of hypertension as a candidate risk factor for POCD [10]. Though we did not assess severity of hypertension which may be important in cognitive risk prediction [48], our finding warrants further enquiry particularly in view of established associations of this risk factor with cognitive impairment per se [15, 49, 50].…”

“…In line with its well-established role as a predictor of age-related cognitive impairment [12-16], we found in our meta-analysis that diabetes was associated with a 26% increased risk of POCD [8]. Findings were less clear for obesity [17], and hypertension was overall not associated with POCD [10]. However, studies included in those meta-analyses were largely exploratory and frequently failed to apply statistical adjustment for potential confounders, which is considered a major limitation.…”

“…Little is currently known about potential risk factors, which help to identify at-risk patients and shed light on underlying pathophysiology. In recent systematic reviews and meta-analyses [7-10], we have shown that patients with metabolic derangement may be at an increased risk of POCD. Indicators of metabolic derangement include classical vascular risk factors such as elevated blood glucose, elevated blood pressure, and obesity, which all tend to correlate [11].…”

Stability of neuropsychological test performance in older adults serving as normative controls for a study on postoperative cognitive dysfunction

“…There is substantial variation in the number and types of neuropsychological tests that have been used in POCD research, however [6]. This hampers comparability between studies and may account for inconsistent results in POCD incidence [7] and epidemiology [8]. Specifically, a priori evaluation of their psychometric properties including their stability over time as measured by test-retest reliability in relevant control samples is rarely considered in test selection.…”