Unconscious trauma patients: outcome differences between southern Finland and Germany-lesson learned from trauma-registry comparisons

Purpose: International trauma registry comparisons are scarce and lack standardised methodology. Recently, we performed a 6-year comparison between southern Finland and Germany. Because an outcome difference emerged in the subgroup of unconscious trauma patients, we aimed to identify factors associated with such difference and to further explore the role of trauma registries for evaluating trauma-care quality.

Methods: Unconscious patients [Glasgow Coma Scale (GCS) 3-8] with severe blunt trauma [Injury Severity Score (ISS) ≥16] from Helsinki University Hospital's trauma registry (TR-THEL) and the German Trauma Registry (TR-DGU) were compared from 2006 to 2011. The primary outcome measure was 30-day in-hospital mortality. Expected mortality was calculated by Revised Injury Severity Classification (RISC) score. Patients were separated into clinically relevant subgroups, for which the standardised mortality ratios (SMR) were calculated and compared between the two trauma registries in order to identify patient groups explaining outcome differences.

Results: Of the 5243 patients from the TR-DGU and 398 from the TR-THEL included, nine subgroups were identified and analyzed separately. Poorer outcome appeared in the Finnish patients with penetrating head injury, and in Finnish patients under 60 years with isolated head injury [TR-DGU SMR = 1.06 (95 % CI = 0.94-1.18) vs. TR-THEL SMR = 2.35 (95 % CI = 1.20-3.50), p = 0.001 and TR-DGU SMR = 1.01 (95 % CI = 0.87-1.16) vs. TR-THEL SMR = 1.40 (95 % CI = 0.99-1.81), p = 0.030]. A closer analysis of these subgroups in the TR-THEL revealed early treatment limitations due to their very poor prognosis, which was not accounted for by the RISC.

Conclusion: Trauma registry comparison has several pitfalls needing acknowledgement: the explanation for outcome differences between trauma systems can be a coincidence, a weakness in the scoring system, true variation in the standard of care, or hospitals' reluctance to include patients with hopeless prognosis in registry. We believe, however, that such comparisons are a feasible method for quality control.