Operating room ventilation-Validation of reported data on 108 067 primary total hip arthroplasties in the Norwegian Arthroplasty Register

Rationale, aims, and objectives The true effect of laminar airflow (LAF) systems on postoperative infection is disputed, partly due to uncertainty regarding the validity of ventilation data in register studies. The aim of this study was to validate the information on operating room (OR) ventilation reported by the orthopaedic surgeons to the Norwegian Arthroplasty Register (NAR) after primary total hip arthroplasty (THA). Method Forty of the 62 public orthopaedic units performing primary THA in Norway during the period 1987-2015 were included. The hospitals' current and previous ventilation systems were evaluated in cooperation with the hospitals head engineer. We identified the type of ventilation system reported to the NAR and compared the information with the factual ventilation in the specific ORs at the time of primary THA. Results A total of 108 067 primary THAs were eligible for assessment. None of the hospitals performed THA in true "greenhouse" (GH) ventilation. Fifty-seven percent of the primary THAs were performed in ORs with LAF and 43% in ORs with conventional, turbulent ventilation (CV). Comparing the reported data with the validated data, LAF was reported with a sensitivity of 86%, specificity of 89%, and positive predictive value (PPV) of 92%, with an accuracy of 88%. CV was reported with a sensitivity of 89%, specificity of 87%, and PPV of 84%, with an accuracy of 88%. The total, mean misreporting rate was 12%. Conclusions Surgeons were not fully aware of what kind of ventilation system they operated in. This study indicates that conclusions based on ventilation data reported on THA in the NAR should not be interpreted without considering the inaccuracy of the data.