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Objectives Osteoarticular infection (OAI) is a feared complication of Staphylococcus aureus bacteraemia (SAB) and is associated with poor outcomes. We aimed to explore the risk of OAI and death following SAB in patients with and without rheumatoid arthritis (RA) and to identify risk factors for OAI in patients with RA. Methods Danish nationwide cohort study of all patients with microbiologically verified first-time SAB between 2006–18. We identified RA, SAB, comorbidities, and RA-related characteristics (e.g. orthopaedic implants and antirheumatic treatment) in national registries including the rheumatology registry DANBIO. We estimated the cumulative incidence of OAI and death and adjusted hazard ratios (HRs, multivariate Cox regression). Results We identified 18 274 patients with SAB (n  = 367 with RA). The 90-day cumulative incidence of OAI was 23.1% (95% CI 18.8; 27.6) for patients with RA and 12.5% (12.1; 13.0) for patients without RA (non-RA) [HR 1.93 (1.54; 2.41)]. For RA patients with orthopaedic implants cumulative incidence was 29.4% (22.9; 36.2) [HR 1.75 (1.08; 2.85)], and for current users of tumor necrosis factor inhibitors (TNFi) it was 41.9% (27.0; 56.1) [HR 2.27 (1.29; 3.98) compared with non-users]. All-cause 90-day mortality following SAB was similar in RA [35.4% (30.6; 40.3)] and non-RA [33.9% (33.2; 34.5), HR 1.04 (0.87; 1.24)]. Conclusion Following SAB, almost one in four patients with RA contracted OAI corresponding to a doubled risk compared with non-RA. In RA, orthopaedic implants and current TNFi use were associated with approximately doubled OAI risk. One in three died within 90 days in both RA and non-RA. These findings encourage vigilance in RA patients with SAB to avoid treatment delay of OAI. [ABSTRACT FROM AUTHOR]

Aims: The purpose of this study was to validate the diagnosis of periprosthetic joint infection (PJI) in the Danish Hip Arthroplasty Register (DHR)., Patients and Methods: We identified a cohort of patients from the DHR who had undergone primary total hip arthroplasty (THA) since 1 January 2005 and followed them until first-time revision, death, emigration or until 31 December 2012. Revision for PJI, as registered in the DHR, was validated against a benchmark which included information from microbiology databases, prescription registers, clinical biochemistry registers and clinical records. We estimated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for PJI in the DHR alone and in the DHR when combined with microbiology databases., Results: In total, 1382 of the 37 826 primary THAs in the DHR were registered as having been revised for any cause once 26 patients with errors in registration had been excluded: 232 of these were for PJI. For this group, the sensitivity was 67%, specificity 95%, PPV 77%, and NPV 92%. Combining the data from the DHR with those from microbiology databases increased the sensitivity to 90% and also improved specificity (100%), PPV (98%) and NPV (98%)., Conclusion: Only two thirds of revisions for PJI were captured in the DHR and only 77% of the PJI reported to the DHR could be confirmed to be infected., Take Home Message: combining the data from the DHR with those from microbiology databases substantially improved the validity of the diagnosis of PJI and should enable future register-based studies., (©2016 The British Editorial Society of Bone & Joint Surgery.)