Background Septic arthritis (SA) is a serious condition associated with significant morbidity and prolonged hospital stays, posing a large economic burden to healthcare systems. It affects 2–10 people per 100,000 and there has been a suggestion that the incidence is increasing due to iatrogenic causes . Our local secondary centre, University Hospitals Coventry and Warwickshire NHS Trust (UHCW NHS Trust), provides care to Coventry and Rugby covering an estimated population of 550,000.
To investigate the incidence of native joint SA in the adult population in a secondary care hospital in the UK.
To investigate whether immunosuppression contributes significantly to the burden of SA.
Methods Patients were retrospectively identified on the basis of the International Classification of Diseases (ICD)-10 coding generated following discharge from hospital for all patients between 2007–11. Exclusion criteria included paediatric patients, diabetic foot, prosthetic joint infections and those who on review were not thought to have SA. The data was analysed using Excel. Formal ethical approval was obtained via the research and development department within the UHCW NHS Trust.
Results A total of 189 admissions were coded as SA. Of these, 103 were excluded (n=74 not thought to have SA on review of the notes, n=26 paediatric patients and n=3 prosthetic joints). Therefore, there were 86 adult admissions for 64 patients with SA.
The average age of these patients was 53.4 years, with the majority of them being males (n=43, 67.2%). The majority of patients had co-morbidities (n=44, 65.7%), with hypertension (n=10, 14.9%) and type 2 diabetes (n=10, 14.9%) being the most prevalent. Joint aspirates were performed on 63.2% (n=56) of admissions and blood cultures on 70.8% (n=63) of admissions. Staphylococcus aureus was the most commonly cultured microbe in both joint fluid (46.4%, n=13) and blood (42.9%, n=3). The knee was the commonest joint involved (n=31, 46.3%). Other commonly affected joints included the small joints of the hands (n=9, 13.4%) and shoulder/acromioclavicular/sternoclavicular joints (n=9, 13.4%).
Interestingly, 23 (35.9%) of the patients were immunocompromised. Of these, 4 patients had a diagnosis of rheumatoid arthritis (RA) and were on steroid treatment alone (n=2), or in combination with disease-modifying anti-rheumatic drugs (n=2). A total of 11 patients had a pre-existing rheumatological diagnosis of which RA was the most common condition (n=6). Two of these patients were not on immunosuppressants. The 5-year mortality was significant at 29.7% (n=19).
Conclusions Our local data showed the incidence of SA to be approximately 3 per 100,000, which is in keeping with proposed figures. Our cohort highlighted that those with pre-existing co-morbidities or those who were immunocompromised were at greatest risk. An ageing population with multiple co-morbidities means the incidence of SA is set to rise. Greater emphasis therefore needs to be placed on improving awareness and optimising treatment.
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Acknowledgements We would like to thank the PPMO team at UHCW NHS Trust.
Disclosure of Interest None declared