# Impact of SARS-CoV-2 subvariants on postoperative outcomes in geriatric hip fracture patients – a multinational multicentre study

## TL;DR

This study examines how different SARS-CoV-2 subvariants affect outcomes in elderly patients who had hip fracture surgery.

## Contribution

The study provides new insights into how specific SARS-CoV-2 subvariants influence postoperative mortality and hospitalization in geriatric hip fracture patients.

## Key findings

- During the Delta and Omicron periods, patients with SARS-CoV-2 had higher mortality and longer hospital stays.
- In the Alpha period, SARS-CoV-2 comorbidity did not significantly affect mortality or hospitalization duration.
- SARS-CoV-2-positive patients showed lower pre-fracture mobility and were more likely to be institutionalized.

## Abstract

Hip fractures (HF) are among the most prevalent diagnoses in geriatric traumatology, with persistently high incidence even during the COVID-19 pandemic. Concomitant SARS-CoV-2 infection adds clinical complexity and has been associated with increased mortality and prolonged hospitalisation. This study aimed to assess the impact of SARS-CoV-2 subvariants B.1.1.7 (Alpha), B.1.617.2 (Delta), and B.1.1.529 (Omicron) on postoperative outcomes in patients undergoing surgical treatment for HF.

A retrospective multicentre study was conducted using data from the German Registry for Geriatric Trauma (ATR-DGU®) between March 2021 and April 2022 across 119 hospitals. 12,707 patients undergoing HF surgery were included and stratified by predominant subvariant periods: Alpha (n = 3714), Delta (n = 5434), and Omicron (n = 3559). Each cohort was further stratified by SARS-CoV-2 status at admission.

During the Alpha period, in-hospital mortality and length of stay were similar between COVID-19-comorbid (8.3%, 13 days) and SARS-CoV-2-negative patients (5.4%, 15 days). In the Delta and Omicron periods, mortality was significantly higher among COVID-19-comorbid patients (14.3% and 13.9%) compared to SARS-CoV-2-negative patients (5.8%, p = 0.017; 5.7%, p < 0.001), with longer hospitalisations (17 vs. 15 days, p < 0.05). COVID-19-comorbid patients were more frequently institutionalised and exhibited lower levels of pre-fracture mobility compared to SARS-CoV-2-negative patients.

COVID-19-positive patients showed lower mortality during the Alpha period and higher mortality during the Delta and Omicron periods. Overall, COVID-19 comorbidity was associated with increased in-hospital mortality and longer hospitalisation. These observations may be influenced by unmeasured confounding.

Not applicable. This retrospective study used anonymized data from the German Registry for Geriatric Trauma (ATR-DGU®) and was approved by the ethics committee of the University of Muenster (reference number: 2022-268-f-S). This study was conducted in accordance with the Declaration of Helsinki.