A systematic review and meta-analysis of the correlation between operation time and postoperative delirium in total hip arthroplasty

Abstract

Background: Delirium is a common postoperative complication of total hip arthroplasty (THA), excessively long time surgery may be one of the factors associated with it. This article aimed to employ literature retrieval and meta-analysis to investigate the correlation between operation time and postoperative delirium in THA. Methods: The databases of PubMed and Springerlink libraries were searched for retrospective case-control studies on delirium-related factors after THA. The retrieved studies were screened according to the inclusion criteria. Newcastle-Ottawa scale (NOS) was used to assess the quality of literatures. After extracting the data of included literatures, RevMan 5.3.5 software was used to analyze the data and obtain a forest plot and funnel plot. Results: A total of 137 literatures were initially screened in this study. According to the inclusion and exclusion criteria and literature quality evaluation, 6 studies were finally included, involving a total of 3,494 patients. The NOS scores were above 6 points in all 6 literatures. Meta-analysis revealed statistical heterogeneity among the 6 studies (I2=80%, P=0.0002). The random effects model was used, revealing that the operation time of patients with postoperative delirium was longer, and the difference was statistically significant [standardized mean difference (SMD) =0.43, 95% confidence interval (CI): 0.20 to 0.66, P=0.0003]. The 6 studies were divided into unilateral or bilateral THA subgroups according to the type of surgery. Homogeneity was detected between the internal literatures: bilateral subgroup (I2=5%, P=0.37), unilateral subgroup (I2=0%, P=0.78). Postoperative delirium was associated with longer operation time in both subgroups, which was consistent with the combined analysis: bilateral subgroup (SMD =0.25, 95% CI: 0.12 to 0.37, P=0.0001), unilateral subgroup (SMD =0.70, 95% CI: 0.55 to 0.84, P=0.0001). Discussion: Operation time is one of the related factors of delirium after THA. The longer the operation time, the greater the possibility of delirium.