Regional differences and mortality-associated risk factors among older patients with septic shock: Administrative data analysis with multilevel logistic regression modeling

Abstract

Abstract Background Older patients with septic shock are generally difficult to treat, have poor outcomes because of frailty and vulnerability, and may be highly sensitive to the quality of clinical care. Therefore, differences in treatment that arise from variations in intensive care unit (ICU) policies and each physician may influence mortality. We hypothesized that regional variability exists in mortality among older patients with septic shock, and investigated mortality-associated factors. Methods Administrative medical claims data were analyzed; participants were enrolled from April 2015 to March 2020. In Japan, engagement of at least one ICU physician exclusively at the ICU is a mandatory requirement to claim governmental incentive. In this study, ICU physicians were differentiated as “intensivist” and “ICU-dedicated physician” based on whether they were board-certified or not, respectively, in intensive care medicine. The primary outcome was the 28-day mortality after ICU admission. Data from nine secondary medical areas with ICU facilities were analyzed. We calculated and compared the 28-day mortality by each area. To adjust for patient characteristics and hospital profiles, multilevel logistic regression analyses were conducted. Results Among our 1,238 participants, mortality varied from 18.3–41.4% across nine areas. Based on multilevel logistic analyses, the model including variables on patient characteristics and hospital profiles was best-fitted, and these variables did not vary significantly across the nine areas. Age group, post-surgical admission, and the number of ICU beds per intensivist were significantly associated with mortality. The adjusted odds ratio for the ratio of ICU beds to intensivist was 2.25 (95% CI [1.36–3.72], p < 0.01), compared with no intensivist versus one or more intensivists for four ICU beds. Conclusions Regional mortality variability of older patients with septic shock was ascertained through our analysis. Mortality may be influenced by whether the ICU physicians are board-certified in intensive care medicine. To ensure quality care of older patients with septic shock, standard criteria, similar to those applied to intensivists, should be considered and applied to ICU physicians.