Should equivocal Bordetella pertussis PCR results in children be reported to public health?

Introduction Real-time polymerase chain reaction (PCR) is the preferred method for the diagnosis of pertussis. In Quebec, positive and equivocal results are reportable to public health; in contrast, in Ontario equivocal results are not reportable. Objective To determine the clinical significance of equivocal, compared with positive results, in children with suspected pertussis. Methods Retrospective cohort of consecutive patients seen at the Centre Hospitalier Universitaire Sainte-Justine in Montreal, Quebec, with suspected pertussis and tested with a bacterial multiplex PCR (including Bordetella pertussis) between 2015 and 2017. Medical records were reviewed using a standardized form. Univariate analyses (Student's t-test and chi-square test) and multivariable logistic regression were used to compare cases of positive and equivocal results. Results Of the 1,526 multiplex PCR performed, 109 were positive and 24 equivocal. Both groups were similar in terms of demographics and disease severity assessments, but patients in the equivocal group had less paroxysmal cough (33.3% vs 79.8%, adjusted odds ratio [aOR] 0.11, 95% confidence interval [CI] 0.04-0.29) and whoop (0% vs 18.3%, p