Periprosthetic Joint Infection Following Total Knee Arthroplasty Is Associated with a Significantly Elevated Risk of Mortality: A Population-Level Database Study.

BACKGROUND: Periprosthetic joint infection (PJI) is the most common reason for revision total knee arthroplasty (TKA). Recent evidence has demonstrated that patients who develop PJI within 1 year following total hip arthroplasty have a significantly elevated risk of mortality within 10 years. Thus, the aim of this study was to compare long-term mortality rates between patients who did and did not develop PJI within 1 year following the index TKA. METHODS: This was a retrospective population-level database study. All eligible participants interacted with a single-payer public health-care system. The primary outcome measure was mortality at 10 years following index TKA; 1- and 5-year mortality were also compared. Mortality was compared for propensity-score-matched groups. RESULTS: Of the total of 263,204 patients who underwent primary TKA in the study period (mean age and standard deviation, 67.9 ± 9.3 years), 1,228 (0.5%) subsequently developed PJI within 1 year. Across the entire sample, patients who developed PJI within 1 year following the index TKA were more likely to be male, have frailty, and have a Charlson-Deyo score of >0; they also had significantly higher rates of congestive heart failure and chronic obstructive pulmonary disease compared with those who did not develop PJI within 1 year. A total of 1,202 patients who developed PJI within 1 year of the index TKA were matched to 1,202 patients who did not develop PJI within 1 year of the index TKA, with standardized differences of <0.10 for all covariates, indicating a robust match. After matching, TKA recipients who developed PJI in the first year had a significantly higher 10-year mortality rate (7.2% [86] versus 1.6% [19]; absolute risk difference = 5.45% [95% confidence interval (CI) = 3.41% to 7.74%]; hazard ratio = 4.66 [95% CI = 2.84 to 7.66]). CONCLUSIONS: Patients who developed PJI within 1 year following TKA were at significantly higher risk for mortality at 10 years post-TKA compared with those who did not develop PJI within 1 year following TKA. The etiological factors leading to this increased risk remain unclear and warrant further investigation alongside efforts to further the prevention, diagnosis, and management of PJI. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.