Reflective Subcategories, Localizations and Factorization Systems: Corrigenda C. Cassidy, M. Hébert and G. M. Kelly, 1980 Mathematics subject classification (Amer. Math. Soc.): 18 A 20.

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Background: Observational studies have suggested that accelerated surgery is associated with improved outcomes in patients with a hip fracture. The HIP ATTACK trial assessed whether accelerated surgery could reduce mortality and major complications. Methods:We randomised 2970 patients from 69 hospitals in 17 countries. Patients with a hip fracture that required surgery and were ≥45 years of age were eligible. Patients were randomly assigned to accelerated surgery (goal of surgery within 6 hours of diagnosis; 1487 patients) or standard care (1483 patients). The co-primary outcomes were 1.) mortality, and 2.) a composite of major complications (i.e., mortality and non-fatal myocardial infarction, stroke, venous thromboembolism, sepsis, pneumonia, life-threatening bleeding, and major bleeding) at 90 days after randomisation. Outcome adjudicators were masked to treatment allocation, and patients were analysed according to the intention-to-treat principle; ClinicalTrials.gov, NCT02027896. Findings:The median time from hip fracture diagnosis to surgery was 6 hours (interquartile range [IQR] 4-9) in the accelerated-surgery group and 24 hours (IQR 10-42) in the standard-care group, p<0.0001. Death occurred in 140 patients (9%) assigned to accelerated surgery and 154 patients (10%) assigned to standard care; hazard ratio (HR) 0.91, 95% CI 0.72-1.14; absolute risk reduction (ARR) 1%, 95% CI -1-3%; p=0.40. The primary composite outcome occurred in 321 patients (22%) randomised to accelerated surgery and 331 patients (22%) randomised to standard care; HR 0.97, 95% CI 0.83-1.13; ARR 1%, 95% CI -2-3%; p=0.71.Interpretation: Among patients with a hip fracture, accelerated surgery did not significantly lower the risk of mortality or a composite of major complications compared to standard care.

This work is a detailed analysis of the relationship between reflective subcategories of a category and factorization systems supported by the category.