BACKGROUND: Trauma centers (TCs) vary in the inclusion of patients with isolated hip fractures (IHFs) in their registries. This inconsistent case ascertainment may have significant implications on the assessment of TC performance and external benchmarking efforts.

METHODS: Data were derived from the National Trauma Data Bank (2007-8.1). We included patients (aged 16 years or older) with Injury Severity Score value ≥ 9 who were admitted to Level I and II TCs. To ensure data quality, we limited the study to TC that routinely reported comorbidities and Abbreviated Injury Scale codes. IHF were defined as patients, aged 65 years or older, injured as a result of falls, with Abbreviated Injury Scale codes for hip fracture and without other significant injuries. TCs were stratified according to their reported inclusion of IHF in their registry. Observed-to-expected mortality ratios were used to rank TC performance first with and then, without the inclusion of patients with IHF.

RESULTS: In total, 91,152 patients in 132 TCs were identified; 5% (n = 4,448) were IHF. The proportion of IHF per TC varied significantly, ranging from 0% to 31%. When risk-adjusted mortality was evaluated, excluding patients with IHF had significant effects: 37% (n = 49) of TCs changed their performance rank by ≥ 3 (range, 1-25) and 12% of centers changed their performance quintile. The greatest change in rank performance was evident in centers that routinely include IHF in their registries.

CONCLUSIONS: Given the fact that IHFs in the elderly significantly influence risk-adjusted outcomes and are variably reported by TCs, these patients should be excluded from subsequent benchmarking efforts.