# Primary septic arthritis in the elderly – a forgotten killer? Five-year survival and risk factors in a retrospective cohort study

## TL;DR

Primary septic arthritis in elderly patients has high mortality, with survival influenced by age, health status, and joint involvement.

## Contribution

This study identifies key risk factors for 5-year survival in elderly patients with primary septic arthritis.

## Key findings

- Survival rates were 76% at 1 year and 54% at 5 years.
- Age, ASA PS classification, CCI, joint involvement, and implants significantly affect survival.
- Patients with implants had notably shorter survival times.

## Abstract

Primary septic arthritis is an acute emergency associated with high morbidity and mortality in older adults. Rapid diagnosis and treatment are crucial. The study evaluates 5-year survival and identifies prognostic risk factors in elderly patients with primary septic arthritis, including age, American Society of Anesthesiology Physical Status (ASA PS) classification, Charlson Comorbidity Index (CCI), joint involvement, implants, and pathogen spectrum.

50 patients aged ≥ 60 years treated for primary septic arthritis at two hospitals between 2008 and 2020 were included. Demographic, clinical, and microbiological data were collected retrospectively. Survival was assessed by Kaplan–Meier analysis, with log-rank tests to compare subgroups.

The mean age was 71.2 years. Overall survival was 76% at 1 year and 54% at 5 years. Survival declined significantly with increasing age (p = 0.004), higher ASA PS classification (p < 0.001), higher CCI (p = 0.006), joint involvement (p = 0.027), and presence of implants (p < 0.001). Diabetes mellitus, osteoarthritis, and synovial culture status showed no significant effect. Mean survival by joint ranged from 3.65 for the knee to 2.41 years for the shoulder. Patients with implants had markedly shorter survival (1.1 years vs. 3.84 years). Pathogens were isolated in 70% of cases, most frequently Staphylococcus aureus (38%).

Primary septic arthritis in older adults remains a life-threatening condition with high early- and mid-term mortality. Survival is strongly determined by age, ASA PS classification, CCI, joint involvement, and presence of implants, while comorbidities and pathogen detection show no prognostic relevance.