RSV Detection and Antibiotic Prescribing Decisions for Pediatric Respiratory Tract Infections

Respiratory syncytial virus (RSV) is a leading cause of pediatric viral lower respiratory tract infections (VLRTIs), often leading to inappropriate antibiotic use. Although rapid antigen diagnostic tests (Ag-RDTs) support clinical diagnosis, their effect on antibiotic prescribing in community settings remains uncertain.

To evaluate the association of RSV Ag-RDT implementation with antibiotic prescribing practices for infants and children assessed for LRTIs.

This retrospective cohort study used data from a community-based primary care setting involving family pediatricians in Italy participating in the Pedianet network. Data were collected between December 2023 and May 2024 from children aged 9 to 36 months with symptoms of VLRTI who underwent RSV Ag-RDT during the 2023-2024 respiratory epidemiologic season and historical matched cohorts.

Children with RSV-positive and RSV-negative Ag-RDT results were compared with each other and with matched historical (2022-2023) and contemporaneous (2023-2024) cohorts of children with clinically diagnosed VLRTIs or bronchiolitis who did not undergo laboratory testing.

The primary outcome was antibiotic prescribing within 14 days of diagnosis. Prescriptions associated with suspected or confirmed bacterial infections (such as elevated C-reactive protein levels or documented coinfections) were excluded. Relative risks (RRs) and 95% CIs were estimated using log-binomial regression models.

Among 256 cases (median age, 15.06 [IQR, 11.61-22.72] months; 133 males [51.95%]), 79 (30.86%) were RSV positive and 177 (69.14%) were RSV negative. These 2 groups were comparable in age, with RSV-negative children slightly younger (median age, 14.95 [IQR, 11.66-22.67] vs 15.34 [IQR, 11.40-23.10] months), and in sex distribution, with a higher proportion of females among RSV-positive cases (41 [51.90%] vs 82 [46.33%]). Antibiotic prescribing was lower in RSV-positive than RSV-negative children (0.18 [95% CI, 0.10-0.25] vs 0.29 [95% CI, 0.22-0.35] prescriptions per 10 person-days) and was associated with a reduction in risk of receiving an antibiotic prescription (RR, 0.52; 95% CI, 0.33-0.83). Implementation of RSV Ag-RDT was associated with lower antibiotic use for VLRTIs compared with a matched untested cohort (RR, 0.54 [95% CI, 0.44-0.66] in 2022-2023 and 0.61 [95% CI, 0.50-0.75] in 2023-2024) and for bronchiolitis in 2022-2023 (RR, 0.56 [95% CI, 0.33-0.95]) but not in 2023-2024 (RR, 0.75 [95% CI, 0.42-1.33]). Reductions were greater among RSV-positive cases: for VLRTIs, the RR was 0.33 (95% CI, 0.20-0.52) in 2022-2023 and 0.41 (95% CI, 0.25-0.67) in 2023-2024; for bronchiolitis, the RR was 0.33 (95% CI, 0.15-0.76) in 2022-2023, but the reduction was not significant in 2023-2024 (RR, 0.43 [95% CI, 0.18-1.00]).

In this cohort of 256 VLRTI cases, the findings suggest that RSV contributed to a broad range of VLRTIs across ages and that RSV Ag-RDT was a useful outpatient antimicrobial stewardship tool, particularly in bronchiolitis. Combined with universal immunoprophylaxis, widespread Ag-RDT use may improve diagnostic accuracy, resource allocation, and clinical outcomes.