Clinical and financial benefits of rapid detection of respiratory viruses: an outcomes study

To assess the expected benefits of rapid reporting of respiratory viruses, we compared patients whose samples were processed using standard techniques such as enzyme immunoassays, shell vial assays, and culture tube assays (year 1) to patients whose samples were processed with the same standard techniques in addition to immunofluorescent testing (FA) directly on cytocentrifuged samples (year 2). The cytospin FA screened for influenza A and B viruses, respiratory syncytial virus (RSV), parainfluenza viruses 1 to 3, and adenovirus (DAKO Diagnostics Ltd.). The specificity of the cytospin FA for all viruses was 100%. The sensitivities for influenza A virus and RSV were 90 and 98%, respectively, but the sensitivities for influenza B virus and adenovirus were unacceptable (14.3 and 0%, respectively). However, since the former viruses account for >85% of our isolates from clinical specimens, the cytospin FA is an excellent screening test since the positive result was available within hours. The mean turnaround time for all positive viruses was 4.5 days in year 1 and 0.9 day in year 2 (P = 0.001). This rapid reporting resulted in physicians having access to information sooner, enabling more appropriate treatment. The mean length of stay in the hospital for inpatients with respiratory viral isolates was 10.6 days for year 1 versus 5.3 days for year 2. Mean variable costs for these patients was $7,893 in year 1 and $2,177 in year 2. After subtracting reagent costs and technological time, the savings in variable costs was $144,332/year. Summarizing, the cytospin FA markedly decreased turnaround time and was associated with decreased mortality, length of stay, and costs and with better antibiotic stewardship.