Validation of reoperations due to infection in the Swedish Hip

29 Background: Complete or almost complete coverage of reoperations is essential to 30 enable a correct interpretation of data in arthroplasty registers. The completeness of 31 recordings due to infection is unknown in the Swedish Hip Arthroplasty Register 32 (SHAR). We therefore used the Swedish Prescribed Drug Register (SPDR) and 33 performed studies of medical records to evaluate this issue. 34 Methods: All patients registered for a primary Total Hip Replacement (THR) in the 35 SHAR between July 1, 2005 and December 31, 2008 were selected for the study 36 (45,531 patients with 49,219 THRs) and were matched with the SPDR. All patients 37 with a minimum of 4 weeks of continuous outpatient antibiotic treatment within 2 38 years after their primary THR (1,989 patients, with 2,219 THRs) were selected for a 39 medical records review to find the THRs reoperated due to infection. 40 Results: 599 (1.2%) of the THRs had been reoperated within 2 years after the index 41 operation and in 47% of these the prosthesis had been revised or extracted. 400 of 42 the THRs were registered for a reoperation in the SHAR resulting in a completeness 43 of 66%. 44 Conclusion: The completeness of registration due to early infection after THR was 45 low and questions whether register data can be used in order to evaluate changes in 46 postoperative infection rates. 47