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The Application of IMPACT in the Elderly with TBI

Taylor and Francis

Background: The International Mission for Prognosis and Clinical Trial Design in TBI (IMPACT) prognostic models have been used to predict outcome following traumatic brain injury (TBI). These models were derived in a cohort primarily composed of randomized controlled trial participants and may not be valid for older patients seen in clinical practice. Patients and Methods: Using data from the National Study on Costs and Outcomes of Trauma (NSCOT) we identified adult patients presenting to US hospitals between July 2001 and November 2002 with non-penetrating moderate or severe TBI (GCS ≤12). The cohort was split into older (65-84 years) and younger (18-64 years) age strata and the predicted risks of death and unfavorable outcome were calculated using the IMPACT core and lab models. Model calibration and discrimination in the older stratum was compared to that in the younger stratum. Results: We identified 202 older patients (weighted n = 268) and 613 younger patients (weighted n = 1,682) with moderate or severe non-penetrating TBI. Older patients more commonly had multiple co-morbidities and used antiplatelets or anticoagulants prior to injury. Older patients were more frequently injured in a fall and three times more likely to be dead within 6 months of injury. IMPACT model discrimination did not differ significantly between older and younger age strata and was generally adequate (c-statistic for the core model predicting death by 6 months, 0.81 [0.77 – 0.84] versus 0.75 [0.66 – 0.84], respectively; p=0.26). IMPACT model calibration was poor for both older and younger strata (Hosmer-Lemeshow p-value for the core model for death by 6 months was 0.01 versus <0.0001, respectively). Pre-specified qualitative graphical evaluation suggested substantial under-prediction of mortality in the oldest decades of life but not among younger patients. Discussion: The examined IMPACT prognostic models demonstrated adequate discrimination but poor calibration in both older and younger strata of a population-based sample of patients with moderate-to-severe TBI. These models should be used with caution when stratifying geriatric TBI populations for the purposes of risk adjustment or clinical trial design.

Postprint

eng

Vancouver : University of British Columbia Library

10.14288/1.0412189

Non UBC; Medicine, Faculty of; Medicine, Department of

10.3109/02699052.2016.1146964

Faculty; Researcher

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