Effect of Plasma Air Purifiers on Infection Rates in Orthopedic Surgery

Surgical site infection (SSI) following orthopedic surgery impacts patient outcomes. Airborne transmission is one potential route of infection. Despite their high cost and resource demands, modern ventilation systems have shown limited efficacy in reducing SSI rates. This trial investigated the effectiveness of a low-cost air purifier in reducing SSI rates after orthopedic surgery.

In a nationwide, multicenter, double-blind, cluster-randomized crossover, placebo-controlled superiority trial, we included all patients undergoing orthopedic surgery during the trial period. The intervention group underwent surgery in operating rooms with active Novaerus NV800 air purifiers, while the control group underwent surgery in operating rooms with the same air purifiers that were inactive. The primary end point was SSI within 12 weeks post surgery, defined as a postsurgery infection marker (PSIM), a custom composite outcome based on registry codes for prescribed antibiotics, diagnoses, and surgical procedures. Logistic regression was performed to evaluate the primary outcome.

Of the 40,547 patients analyzed, 19,869 were in the intervention group and 20,678 in the control group. The PSIM rate was 9.2% in the invention group, and 9.4% in the control group, with an odds ratio of 0.98 (95% confidence interval, 0.91 to 1.05) for the intervention group. This finding remained consistent across various subgroups based on diagnoses, hospital levels, and ventilation types.

In modern operating rooms equipped with standard, midrange airflow ventilation systems, the addition of wall-mounted plasma air purifiers did not reduce the PSIM rate after orthopedic surgery. (Funded by the Swedish Research Council; grant number, 2017-00198; ClinicalTrials.gov number, NCT02695368.).