Risk of Staphylococcus aureus bacteraemia in patients with rheumatoid arthritis and the effect of orthopaedic implants on the risk: a nationwide observational cohort study

Abstract

Objective

It remains disputed how much the risk of Staphylococcus aureus bacteraemia (SAB) is increased in patients with rheumatoid arthritis (RA), and the extent to which orthopaedic implants explain the risk. We assessed SAB incidence rates (IRs) and incidence rate ratios (IRRs), comparing RA patients with a general population cohort (GPC) and individuals with versus without orthopaedic implants.

Method

Danish residents aged ≥ 18 years without prior RA or SAB (=GPC) were followed up for RA and microbiologically verified SAB events (1996–2017). IRRs were calculated by age- and sex-stratified Poisson regression adjusted for age, comorbidities, calendar year, and socioeconomic status.

Results

The GPC comprised 5 398 690 individuals. We identified 33 567 incident RA patients (=RA cohort) (median follow-up 7.3 years, IQR 3.6–12.3). We observed 25 023 SAB events (n = 224 in the RA cohort). IRs per 100 000 person-years were 81.0 (RA cohort) and 29.9 (GPC). IRs increased with age. Adjusted IRRs in 18–59-year-old RA patients were 2.6 (95% confidence interval 1.8–3.7) for women and 1.8 (1.1–3.1) for men, compared with same sex and age group GPC. IRRs declined with age. Compared with the GPC without implants, IRRs for RA patients with implants ranged from 1.9 (1.3–2.8) (women ≥ 70 years) to 5.3 (2.2–12.8) (18–59-year-old men).

Conclusion

In this nationwide registry-based cohort study RA was a risk factor for SAB, and orthopaedic implants further increased the risk. Clinicians should be aware of potential SAB in patients with RA and orthopaedic implants.

Acknowledgements

We wish to thank patient representative Pia Lüchau Pedersen for her contribution to the development of the hypothesis and the Danish Rheumatism Association and Beckett-Fonden for their financial support.

Authors contributions

Sabine Sparre Dieperink, Merete Lund Hetland, Bente Glintborg, Louise Bruun Oestergaard, Mette Nørgaard, Thomas Benfield, Frank Mehnert, and Andreas Petersen contributed to the hypotheses and study design. Statistical analyses were performed by Sabine Sparre Dieperink, Louise Bruun Oestergaard, Frank Mehnert, and Christian Torp-Pedersen. All authors contributed to the interpretation of data and critical revision of the manuscript.

Disclosure statement

SSD received financial support from The Danish Rheumatism Association and Beckett-Fonden for the submitted work; outside the submitted work, BG received research grants from Pfizer, AbbVie and BMS; TB had contracts as principal investigator in clinical studies and received research grants, honorariums and consulting fees from Novo Nordisk Foundation, Simonsen Foundation, Lundbeck Foundation, Kai Foundation, Erik and Susanna Olesen’s Charitable Fund, GSK, Pfizer, Boehringer Ingelheim, Gilead Sciences, MSD, Roche, Novartis, Kancera AB and AbbVie and received trial medication for a clinical trial from Eli-Lilly; CTP received research grants from Bayer and Novo Nordisk Foundation; MLH received research grants from AbbVie, Biogen, BMS, Celltrion, Eli-Lilly, Janssen Biologics B.V, Lundbeck Foundation, MSD, Pfizer, Roche, Samsung Biopies, Sandoz and Novartis and chairs the steering committee of the Danish Rheumatology Quality Registry (DANBIO), which receives public funding from the hospital owners and funding from pharmaceutical companies and co-chairs EuroSpA, which generates real-world evidence of treatment of psoriatic arthritis and axial spondyloarthritis based on secondary data and is partly funded by Novartis.

Supplementary material

Supplemental data for this article can be accessed https://doi.org/10.1080/03009742.2022.2049057.

Additional information

Funding

This study was partly funded by the Danish Rheumatism Association [grant numbers R163-A5715 and R188-A6548] and by Beckett-Fonden [application reference number 19-2-5090].