Metabolic Syndrome Components and Its Impact on Acute Kidney Injury After Total Joint Arthroplasty.

Background: Metabolic syndrome (MetS) is an independent risk factor for postoperative complications. This study aimed to evaluate the associated risk of MetS for perioperative complications, especially urinary complications, in patients who underwent primary total knee arthroplasty (TKA) or total hip arthroplasty (THA).

Methods: We used a publicly available all-payer administrative database to identify patients undergoing TKA and THA from 2016 to 2020. The primary exposure of interest was MetS. Multivariable adjusted models based on propensity score matching were used to evaluate the association of MetS components with acute kidney injury (AKI), urinary tract infection (UTI), and acute posthemorrhagic anemia (APHA) in patients who underwent TKA and THA. A counterfactual-based mediation analysis was conducted to investigate the mediating effect of APHA on the relationship between MetS and AKI.

Results: The analysis included 2,097,940 (16.4% with MetS) THA and 3,073,310 (24.0% with MetS) TKA adult hospitalizations. Multivariable adjustment analysis indicated MetS was associated with an increased risk of AKI (odds ratio [OR] 1.78, 95% confidence interval [CI] 1.69 to 1.89 for THA; OR 1.88, 95% CI 1.79 to 1.96 for TKA), UTI (OR 1.13, 95% CI 1.03 to 1.23 for THA; OR 1.26, 95% CI 1.17 to 1.35 for TKA), and APHA (OR 1.17, 95% CI 1.14 to 1.20 for THA; OR 1.7, 95% CI 1.15 to 1.19 for TKA). The risk of AKI increased with the number of MetS components, with ORs ranging from 2.58 to 9.46 in TKA patients and from 2.22 to 5.75 in THA patients. This increase was particularly associated with diabetes and hypertension, which were the most significant associated risk factors. Furthermore, APHA mediated the association between MetS and AKI.

Conclusions: The prevalence of MetS is increasing in TKA and THA patients. Metabolic syndrome was associated with increased risk of AKI, UTI, and APHA. The risk of AKI increased with each additional MetS component, with diabetes and hypertension contributing most. In addition, APHA may play a partial mediating role in MetS-induced AKI.