Associate Director, Epidemiology Johnson & Johnson, United States
Background: Few contemporary long bone non-union analyses have been performed in the United States.
Objectives: Our study was designed to provide a current understanding of non-union rates and risk factors.
Methods: The IBM® MarketScan® Commercial Claims and Encounters database was used for this analysis. Patients with long bone (femur, tibia or humerus) fracture in the inpatient setting, and a surgical fracture repair procedure, from Q4 2015 to most recent, were identified. Exclusion criteria included: polytrauma and amputation at index. The primary outcome was a diagnosis of non-union in the 2-years post-index. Additional outcomes included concurrent infection, and reoperation. Age, gender, comorbidities, fracture characteristics and severity were identified for all patients. Descriptive analyses were performed on all 3 cohorts separately. Crude and adjusted rates of non-union (using Poisson regressions with log link) were calculated. Risk ratios (RR) for non-union were estimated and presented with 95% confidence intervals.
Results: 12,770, 13,504 and 4,805 patients with femoral, tibial or humeral surgically-treated fractures were identified [(average age: 36-44, average Elixhauser Comorbidity Index (ECI): 1.04 (standard deviation (SD): 1.60) (tibia) to 1.61 (SD: 2.20) (femur)]. Shaft fractures affected 37.9% (femur), 57.1% (tibia) and 40.2% (humerus) cases, > 74% of all fractures were displaced, 18-27% were comminuted. For femur fractures, 2.7% were Gustilo Type III versus 9.7% for tibial fractures and < 1% for humerus fractures. The cumulative hazard for non-union at the 2-years post-index time point reached 8.5% (8.0%-9.1%), 9.1% (8.6%-9.7%) and 7.2% (6.4%-8.1%) in the femoral, tibial and humeral fracture cohorts, respectively. Complex fractures (open vs closed, Gustilo III vs Gustilo I-II) also increased risk for non-union (RR for Gustilo III fracture (vs closed) for femur: 1.96 (1.47-2.61), for tibia: 3.33 (2.85-3.88), risk ratio for open (vs closed) for humerus: 1.74 (1.30-2.33)). Risk ratios associated with patient comorbidities were lower than those related to fracture location or complexity.
Conclusions: Non-union post-fracture repair surgery is not uncommon with the greatest risk factors related to the severity and clinical presentation of the fracture.
