The Frank Stinchfield Award: Total Hip Arthroplasty for Femoral Neck Fracture Is Not a Typical DRG 470: A Propensity-matched Cohort Study

Background Hip fractures are a major public health concern. For displaced femoral neck fractures, the needs for medical services during hospitalization and extending beyond hospital discharge after total hip arthroplasty (THA) may be different than the needs after THA performed for osteoarthritis (OA), yet these differences are largely uncharacterized, and the Medicare Severity Diagnosis-Related Groups system does not distinguish between THA performed for fracture and OA.

Questions/purposes (1) What are the differences in in-hospital and 30-day postoperative clinical outcomes for THA performed for femoral neck fracture versus OA? (2) Is a patient’s fracture status, that is whether or not a patient has a femoral neck fracture, associated with differences in in-hospital and 30-day postoperative clinical outcomes after THA?

Methods The National Surgical Quality Improvement Program (NSQIP) database, which contains outcomes for surgical patients up to 30 days after discharge, was used to identify patients undergoing THA for OA and femoral neck fracture. OA and fracture cohorts were matched one-to-one using propensity scores based on age, gender, American Society of Anesthesiologists grade, and medical comorbidities. Propensity scores represented the conditional probabilities for each patient having a femoral neck fracture based on their individual characteristics, excluding their actual fracture status. Outcomes of interest included operative time, length of stay (LOS), complications, transfusion, discharge destination, and readmission. There were 42,692 patients identified (41,739 OA; 953 femoral neck fractures) with 953 patients in each group for the matched analysis.

Results For patients with fracture, operative times were slightly longer (98 versus 92 minutes, p = 0.015), they experienced longer LOS (6 versus 4 days, p < 0.001), and the overall frequency of complications was greater compared with patients with OA (16% versus 6%, p < 0.001). Although the frequency of preoperative transfusions was higher in the fracture group (2.0% versus 0.2%, p = 0.002), the frequency of postoperative transfusion was not different between groups (27% versus 24%, p = 0.157). Having a femoral neck fracture versus OA was strongly associated with any postoperative complication (odds ratio [OR], 2.8; 95% confidence interval [CI], 2.1-3.8]; p < 0.001), unplanned readmission (OR, 1.8; 95% CI, 1.0-3.2; p = 0.049), and discharge to an inpatient facility (OR, 1.7; 95% CI, 1.4-2.0; p < 0.001).

Conclusions Compared with THA for OA, THA for femoral neck fracture is associated with greater rates of complications, longer LOS, more likely discharge to continued inpatient care, and higher rates of unplanned readmission. This implies higher resource utilization for patients with a fracture. These differences exist despite matching of other preoperative risk factors. As healthcare reimbursement moves toward bundled payment models, it would seem important to differentiate patients and procedures based on the resource utilization they represent to healthcare systems. These results show different expected resource utilization in these two fundamentally different groups of patients undergoing hip arthroplasty, suggesting a need to modify healthcare policy to maintain access to THA for all patients.

Level of Evidence Level III, therapeutic study.