Multiplex PCR point of care testing versus routine, laboratory-based testing in the treatment of adults with respiratory tract infections: a quasi-randomised study assessing impact on length of stay and antimicrobial use

Andrews, Denise; Chetty, Yumela; Cooper, Ben S.; Virk, Manjinder; Glass, Stephen K; Letters, Andrew; Kelly, Philip A.; Sudhanva, Malur; Jeyaratnam, Dakshika

We found no evidence for an association between respiratory multiplex PCR (BioFire FilmArray®) POC testing and length of hospital stay when compared to our routine, laboratory-based respiratory PCR and serology testing. There was an association between POC testing and the antibiotic prescribing decision within 24 h after the result. POC testing also produced results considerably faster than laboratory-based assays. We did not investigate whether the POC results actually influenced decision making and the association with the prescribing decision may only reflect that the FilmArray® result was available before the antibiotics were prescribed and not that the prescriber considered the FilmArray® result in their decision making. Similar percentages of patients Analysed with a negative binomial regression All models adjusted for age, sex, Charlson and Potts scores, day of week, and admission values of WCC and CRP and used multiple imputation to account for missing data. The CURB-65 score was not available for 59% of patients, and was therefore not adjusted for in statistical models. There was less than 5% missing data for all covariates. Missing outcome variables 1) Antibiotics within 72 h and 2) Antibiotics at any time: missing data for 13 patients in the control arm and 10 patients in the intervention arm, 3) Time to antibiotics in the first 72 h: missing data for 1 patient in the intervention arm, 4) duration of antibiotics: missing data for 4 patients in the control arm and 13 in the intervention arm, 5) readmission: missing data for 1 patient in intervention arm, 6) mortality: missing data for 1 patient in intervention arm Control arm de-escalate: 2 stop ≥1 antimicrobial, 3 substitution of Beta-lactam with narrower spectrum Beta-lactam. Intervention arm de-escalate: 2 stop ≥1 antimicrobial, 2 substitution of Beta-lactam with narrower spectrum Beta-lactam, 2 substitution of Beta-lactam with narrower spectrum Beta-lactam and atypical agent was stopped. Control arm escalate: 4 add antibiotic to existing antibiotics (all agents against atypical pneumonia). Intervention arm escalate: 19 add antibiotics to existing antibiotics (14 agents against atypical pneumonia, 5 addition of agents against 'typical pneumonia' to atypical agent e.g. Beta-lactam or teicoplanin with ciprofloxacin if penicillin allergic), 7 substitution of Beta-lactam with broader spectrum Beta-lactam received antibiotics in both study arms. There were no significant differences for the remaining secondary outcomes between the two study arms. The hypothesis was that POC testing would reduce the length of stay. However, though the POC test was 1 day faster than laboratory-based testing, the results were available later than anticipated. This was not due to testing performance of FilmArray®, which took only 65 min but related to a delay in the processing of the specimen by the clinical staff on the ward. Sixty-eight percent of POC tests were performed by study investigators reflecting the fact that the study protocol was not initiated by clinical staff as soon as the patient was admitted to the study ward in many cases. Instead testing was delayed until the study investigators visiting the study wards initiated the study protocol. This resulted in a significant delay in time to results. This is in contrast to a trial of MRSA POC screening by our AMU ward staff that had a TAT from admission of 3.7 h [20] . MRSA testing is mandatory and most patients were eligible for inclusion.