Background: Pneumonia and urinary tract infections (UTIs) increase morbidity and mortality. There is little epidemiological evidence from large population-based studies on risk factors for these infections and subsequent mortality in total hip arthroplasty (THA) patients.
Aim: To examine the risk factors of postoperative pneumonia and UTI after THA and their impact on survival.
Patients and methods: We used the Danish Hip Arthroplasty Register to identify THAs due to osteoarthritis registered from 2000 to 2013. We collected data about comorbidities, mortality and infections in relation to primary hospitalization and potential predictive variables from administrative databases. Regression models were used to estimate associations between potential risk factors and infection, and subsequently, between infection and mortality.
Results: In total 84,812 THAs were included. The cumulative incidence of pneumonia and UTI within 7 days of the primary procedure were 0.21 (95% confidence interval [CI]: 0.18-0.25) and 0.29 (95% CI: 0.26-0.33), respectively. Patient-related risk factors for infection were being 80 years or older, gender and a comorbidity burden at time of surgery. The hazard ratio (HR) of dying within 90 days of the primary THA was 10.67 (95% CI: 5.79-19.57) compared to patients without pneumonia. For patients with UTIs, the HR was 1.64 (95% CI: 0.41-6.59) compared to those without a UTI.
Conclusion: Pneumonia was associated with an increased short-term risk of dying, despite adjustment for coexisting comorbidity and other potential confounders. Age, gender and comorbidity were the most important risk factors for pneumonia and UTIs. Individual initiatives to reduce the risk of pneumonia in select patient groups may be essential to the effort to optimize outcomes after a THA.
Keywords: mortality; pneumonia; prognosis; risk factor; total hip arthroplasty; urinary tract infection.