Impact of trauma centre accreditation on mortality and complications in a Canadian trauma system: an interrupted time series analysis

Background Periodic external accreditation visits aiming to determine whether trauma centres are fulfilling the criteria for optimal care are part of most trauma systems. However, despite the growing trend towards accreditation of trauma centres, its impact on patient outcomes remains unclear. In addition, a recent systematic review found inconsistent results on the association between accreditation and patient outcomes, mostly due to the lack of robust controls. We aim to address these gaps by assessing the impact of trauma centre accreditation on patient outcomes, specifically in-hospital mortality and complications, using an interrupted time series (ITS) design. Methods We included all major trauma admissions to five level I and four level II trauma centres in Quebec, Canada between 2008 and 2017. In order to perform ITS, we first obtained monthly and quarterly estimates of the proportions of in-hospital mortality and complications, respectively, for level I and level II centres. Prognostic scores were used to standardise these proportions to account for changes in patient case mix and segmented regressions with autocorrelated errors were used to estimate changes in levels and trends in both outcomes following accreditation. Results There were 51 035 admissions, including 20 165 for major trauma during the study period. After accounting for changes in patient case mix and secular trend in studied outcomes, we globally did not observe an association between accreditation and patient outcomes. However, associations were heterogeneous across centres. For example, in a level II centre with worsening preaccreditation outcomes, accreditation led to -9.08 (95% CI -13.29 to -4.87) and -9.60 (95% CI -15.77 to -3.43) percentage point reductions in mortality and complications, respectively. Conclusion Accreditation seemed to be beneficial for centres that were experiencing a decrease in performance preceding accreditation.