Seasonality of mortality and in-hospital complications in hip fracture surgery: Retrospective cohort research using a nationwide inpatient database.

AIM

Among older patients undergoing hip fracture surgery, previous studies have shown a seasonal variation of in-hospital surgical complications. However, little is known about seasonal effects on mortality and systemic complications after hip fracture surgery. In the present study, we evaluated whether mortality and in-hospital systemic complications are influenced by seasonal differences.

METHODS

We enrolled patients from a nationwide database who underwent hip fracture surgery between 2010 and 2018. The primary outcome was in-hospital mortality. The secondary outcomes were in-hospital systemic complications. The association between the seasonality and in-hospital outcomes was investigated using multivariable Cox, logistic regression and causal mediation analysis.

RESULTS

With 425 856 patients (mean age 83.5 years; 79% women), overall in-hospital mortality was 5324 (1.2%). Fall and winter were associated with a higher mortality than spring (hazard ratio [HR] 1.16; P < 0.001; HR 1.14; P = 0.001, respectively). Across all the seasons, there were 36 834 overall systemic complications (8.6%), with respiratory infection being the most frequent (18 637 [4.4%]). Among these complications, only respiratory infection showed seasonal variation, with a higher prevalence in fall and winter. The mediated effect of respiratory infection on mortality was significantly higher in fall and winter compared with spring (fall, HR 1.06, proportion mediated 36.7%; winter, HR 1.14, proportion mediated 55.0%; all P < 0.001).

CONCLUSIONS

We found a significantly higher mortality in fall and winter after hip fracture surgery. Specifically, in winter, the increased in-hospital death was largely attributed to the increased incidence of respiratory infection. Geriatr Gerontol Int 2021; 21: 398-403.