Preoperative Hyponatremia is a Risk Factor for Adverse 30-Day Outcomes Following Total Hip Arthroplasty

The relationship between preoperative hyponatremia and 30-day outcomes following total hip arthroplasty (THA) is currently unknown. The present study used prospectively collected data to quantify the association between preoperative hyponatremia and odds of major morbidity (MM), longer length of stay, readmission, and reoperation within 30 days following THA. Patients who underwent THA between 2012 and 2014 were identified in the National Surgical Quality Improvement Program database using validated Current Procedural Terminology codes. Patients were included if they were either normonatremic or hyponatremic preoperatively. The outcome measures in this study were 30-day MM, hospital length of stay, 30-day readmission, and 30-day reoperation. A unique multivariable logistic regression model was used for each outcome to identify statistically significant associations between hyponatremia and the outcome of interest after adjusting for covariates. From 2012 to 2014, 59,236 THA procedures were recorded in National Surgical Quality Improvement Program, of which 55,611 patients were normonatremic and 3,051 patients were hyponatremic. After adjusting for covariates, preoperative hyponatremia was significantly associated with increased odds of MM (odds ratio [OR] = 1.14; 99% confidence interval [CI]: 1.01–1.30), 30-day reoperation (OR = 1.18; 99% CI: 1.02–1.36), and longer hospital length of stay (OR = 1.20; 99% CI: 1.13–1.27). Hyponatremia was not significantly associated with greater odds of 30-day readmission (OR = 0.91; 99% CI: 0.82–1.01). Preoperative hyponatremia was significantly associated with adverse 30-day outcomes following THA. As the U.S. health care system continues to transition toward value-based reimbursement that emphasizes health care quality, the results of the present study can be used to improve patient selection and preoperative counseling.