Per Hviid Gundtoft

The “true” incidence of surgically treated deep prosthetic joint infection after 32,896 primary total hip arthroplasties: A prospective cohort study

Background and purpose — It has been suggested that the risk of prosthetic joint infection (PJI) in patients with total hip arthroplasty (THA) may be underestimated if based only on arthroplasty registry data. We therefore wanted to estimate the “true” incidence of PJI in THA using several data sources. Patients and methods — We searched the Danish Hip Arthroplasty Register (DHR) for primary THAs performed between 2005 and 2011. Using the DHR and the Danish National Register of Patients (NRP), we identified first revisions for any reason and those that were due to PJI. PJIs were also identified using an algorithm incorporating data from microbiological, prescription, and clinical biochemistry databases and clinical findings from the medical records. We calculated cumulative incidence with 95% confidence interval. Results — 32,896 primary THAs were identified. Of these, 1,546 had first-time revisions reported to the DHR and/or the NRP. For the DHR only, the 1- and 5-year cumulative incidences of PJI were 0.51% (0.44–0.59) and 0.64% (0.51–0.79). For the NRP only, the 1- and 5-year cumulative incidences of PJI were 0.48% (0.41–0.56) and 0.57% (0.45–0.71). The corresponding 1- and 5-year cumulative incidences estimated with the algorithm were 0.86% (0.77–0.97) and 1.03% (0.87–1.22). The incidences of PJI based on the DHR and the NRP were consistently 40% lower than those estimated using the algorithm covering several data sources. Interpretation — Using several available data sources, the “true” incidence of PJI following primary THA was estimated to be approximately 40% higher than previously reported by national registries alone.

Validation of the diagnosis 'prosthetic joint infection' in the Danish Hip Arthroplasty Register

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.

Increased Mortality After Prosthetic Joint Infection in Primary THA

BackgroundRevision for prosthetic joint infection (PJI) has a major effect on patients’ health but it remains unclear if early PJI after primary THA is associated with a high mortality.Questions/Purposes(1) Do patients with a revision for PJI within 1 year of primary THA have increased mortality compared with patients who do not undergo revision for any reason within 1 year of primary THA? (2) Do patients who undergo a revision for PJI within 1 year of primary THA have an increased mortality risk compared with patients who undergo an aseptic revision? (3) Are there particular bacteria among patients with PJI that are associated with an increased risk of death?MethodsThis population-based cohort study was based on the longitudinally maintained Danish Hip Arthroplasty Register on primary THA performed in Denmark from 2005 to 2014. Data from the Danish Hip Arthroplasty Register were linked to microbiology databases, the National Register of Patients, and the Civil Registration System to obtain data on microbiology, comorbidity, and vital status on all patients. Because reporting to the register is compulsory for all public and private hospitals in Denmark, the completeness of registration is 98% for primary THA and 92% for revisions (2016 annual report). The mortality risk for the patients who underwent revision for PJI within 1 year from implantation of primary THA was compared with (1) the mortality risk for patients who did not undergo revision for any reason within 1 year of primary THA; and (2) the mortality risk for patients who underwent an aseptic revision. A total of 68,504 primary THAs in 59,954 patients were identified, of those 445 primary THAs underwent revision for PJI, 1350 primary THAs underwent revision for other causes and the remaining 66,709 primary THAs did not undergo revision. Patients were followed from implantation of primary THA until death or 1 year of followup, or, in case of a revision, 1 year from the date of revision.ResultsWithin 1 year of primary THA, 8% (95% CI, 6%–11%) of patients who underwent revision for PJI died. The adjusted relative mortality risk for patients with revision for PJI was 2.18 (95% CI, 1.54–3.08) compared with the patients who did not undergo revision for any cause (p < 0.001). The adjusted relative mortality risk for patients with revisions for PJI compared with patients with aseptic revision was 1.87 (95% CI, 1.11–3.15; p = 0.019). Patients with enterococci-infected THA had a 3.10 (95% CI, 1.66–5.81) higher mortality risk than patients infected with other bacteria (p < 0.001).ConclusionsRevision for PJI within 1 year after primary THA induces an increased mortality risk during the first year after the revision surgery. This study should incentivize further studies on prevention of PJI and on risk to patients with the perspective to reduce mortality in patients who have had THA in general and for patients with PJI specifically.Level of EvidenceLevel III, therapeutic study.

The Danish Hip Arthroplasty Register

Aim of database The aim of the Danish Hip Arthroplasty Register (DHR) is to continuously monitor and improve the quality of treatment of primary and revision total hip arthroplasty (THA) in Denmark. Study population The DHR is a Danish nationwide arthroplasty register established in January 1995. All Danish orthopedic departments – both public and private – report to the register, and registration is compulsory. Main variables The main variables in the register include civil registration number, indication for primary and revision surgery, operation date and side, and postoperative complications. Completeness of primary and revision surgery is evaluated annually and validation of a number of variables has been carried out. Descriptive data A total of 139,525 primary THAs and 22,118 revisions have been registered in the DHR between January 1, 1995 and December 31, 2014. Since 1995, completeness of procedure registration has been high, being 97.8% and 92.0% in 2014 for primary THAs and revisions, respectively. Several risk factors, such as comorbidity, age, specific primary diagnosis and fixation types for failure of primary THAs, and postoperative complications, have been identified through the DHR. Approximately 9,000 primary THAs and 1,500 revisions are reported to the register annually. Conclusion The DHR is important for monitoring and improvement of treatment with THA and is a valuable tool for research in THA surgery due to the high quality of prospective collected data with long-term follow-up and high completeness. The register can be used for population-based epidemiology studies of THA surgery and can be linked to a range of other national databases.

One-year incidence of prosthetic joint infection in total hip arthroplasty: a cohort study with linkage of the Danish Hip Arthroplasty Register and Danish Microbiology Databases

OBJECTIVE To examine the trend of Prosthetic Joint Infections (PJI) following primary total hip arthroplasty (THA) and the antimicrobial resistance of the bacteria causing these infections. MATERIALS AND METHODS We identified a population-based cohort of patients in the Danish Hip Arthroplasty Register (DHR) who had primary THA and received their surgery in Jutland or Funen between 2005 and 2014. We followed the patients until revision, emigration, death, or up to 1-year of follow-up. Data from the DHR were combined with those from microbiology databases, the National Register of Patients, and the Civil Registration System. We estimated the cumulative 1-year incidence of PJI for two 5-year periods; 2005-2009 and 2010-2014. The hazard ratio of PJI as a measure of relative risk after adjusting for multiple risk factors was calculated. RESULTS Of 48,867 primary THAs identified, 1120 underwent revision within 1 year. Of these, 271 were due to PJI. The incidence of PJI was 0.53% (95% confidence interval (CI): 0.44; 0.63) during 2005-2009 and 0.57% (95% CI: 0.49; 0.67) during 2010-2014. The adjusted relative risk was 1.05 (95% CI: 0.82; 1.34) for the 2010-2014 period vs the 2005-2009 period. The most common micro-organisms identified in the 271 PJI were Staphylococcus aureus (36%) and coagulase-negative staphylococci (CoNS) (33%); others commonly identified included Enterobacteriaceae, enterococci, and streptococci. Antimicrobial resistance to beta-lactams and gentamicin did not change during the study period. CONCLUSION The risk of PJI within 1-year after primary THA and the antimicrobial resistance of the most prevalent bacteria remained unchanged during the 2005-2014 study period.