Predictors of in-hospital mortality in nonsurgical departments: a multivariable regression analysis of 2 855 029 hospitalizations.

In‑hospital mortality is a relevant outcome of hospital admissions. This study aimed to identify predictors independently associated with in‑hospital mortality in nonsurgical departments. In 2014, the Polish National Health Fund database provided data on 2 855 029 hospitalizations of adults, which were not related with surgical procedures. Patients' age and sex, diagnosis‑related group category assigned to the hospitalization, length of stay, types of hospital and admission, and day of the week and month of admission were analyzed as mortality predictors. The mean (SD) in‑hospital mortality rate was 4.1% (0.01%). Odds ratios for in‑hospital death increased with patients' age. The female sex was associated with lower odds ratios of death than the male sex. Among the diagnosis‑related groups assigned to hospitalizations, the highest mortality was found in patients with vascular diseases (11.95%). Considering the length of stay, the lowest mortality occurred during 5- to 7‑day (2.63%). Compared with teaching hospitals, the odds ratio of death was 1.31‑fold higher for regional hospitals, 1.35‑fold higher for private hospitals, and 1.48‑fold higher for district and city hospitals; 92% of all in‑hospital deaths occurred after urgent and emergency admissions. Hospital admissions at weekends or on other nonworking days (public holidays) were significant predictors of in‑hospital mortality. Differences in mortality rates were found between particular months, but no seasonal relationship was established. Age, male sex, emergency admission, admission at the weekend or on another nonworking day (during public holidays), and hospitalization in a district, city, private, or regional hospital (compared with a university hospital) were factors associated with higher mortality in nonsurgical departments.