Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)This study aims to analyze whether the interval from hospital admission to surgery may be used as a surrogate of the actual gap from fracture to surgery when investigating in-hospital hip fracture mortality. After analyzing 3,754 hip fracture admissions, we concluded that those intervals might be used interchangeably without misinterpretation bias. The debate regarding the influence of time to surgery in hip fracture (HF) mortality is one of the most controversial issues in the HF medical literature. Most previous investigations actually analyzed the time from hospital admission to surgery as a surrogate of the less easily available gap from fracture to surgery. Notwithstanding, the assumption of equivalency between those intervals remains untested. We analyzed 3,754 hospital admissions of elderly patients due to HF in Quebec, Canada. We compared the performance as predictors of in-hospital mortality of the delay from admission to surgery and the actual gap from fracture to surgery using univariate and multiple logistic regression analysis. The mean times from fracture to surgery and from admission to surgery were 1.84 and 1.02 days (P < 0.001), respectively. On univariate logistic regression, both times were slightly significant as mortality predictors, yielding similar odds ratios of 1.08 (P < 0.001) for time from fracture to surgery and 1.11 (P < 0.001) for time from admission to surgery. After accounting for other covariates, neither times remained significant mortality predictors. The gap from admission to surgery may be used as a surrogate of the actual delay from fracture to surgery when studying in-hospital HF mortality.205723729Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)