Palivizumab immunoprophylaxis effectiveness in children with cystic fibrosis
Almut G Winterstein1, Efe Eworuke, Dandan Xu
1Department of Pharmaceutical Outcomes and Policy, College of Pharmacy, University of Florida, Gainesville, Florida 32610-0494, USA. almut@cop.ufl.edu
Insights
Effectiveness of palivizumab for preventing respiratory syncytial virus (RSV) hospitalizations in cystic fibrosis (CF) infants was inconclusive. While RSV hospitalization rates were low, palivizumab showed a potential benefit, but more data is needed.
Area of Science:
- Pediatric pulmonology
- Infectious disease epidemiology
- Pharmaceutical research
Background:
- Limited evidence exists on the efficacy of palivizumab for respiratory syncytial virus (RSV) immunoprophylaxis in children with cystic fibrosis (CF).
- Cystic fibrosis patients are at increased risk for severe respiratory infections, including those caused by RSV.
Purpose of the Study:
- To evaluate the effectiveness of palivizumab in preventing RSV-related hospitalizations and acute respiratory infections (ARI) in young children with CF.
- To assess the association between palivizumab use and hospitalization rates for RSV and ARI in a pediatric CF cohort.
Main Methods:
- A cohort of 1,974 infants (0-2 years) with CF was established using linked Medicaid and Cystic Fibrosis Registry data (1999-2006).
- Hospitalizations for RSV infections (RSV-ha) and acute respiratory infections (ARI-ha) were analyzed using Cox regression, adjusting for RSV risk factors and CF severity via propensity scores.
- Palivizumab exposure was categorized as current, former, or no exposure based on pharmacy and procedure claims.
Main Results:
- The cohort experienced low rates of RSV-ha (3.9/1,000 season months) and ARI-ha (26.2/1,000 season months).
- Adjusted analyses showed no statistically significant reduction in RSV-ha (HR: 0.57, 95% CI: 0.20-1.60) or ARI-ha (HR: 0.85, 95% CI: 0.59-1.21) with current palivizumab use compared to no use.
- Increasing age was associated with a 5.8% reduction in ARI-ha per month.
Conclusions:
- Low RSV hospitalization incidence in CF patients may indicate underdiagnosis of RSV or a limited role of RSV in respiratory infections in this population.
- While unadjusted and adjusted RSV hospitalization rates suggested a potential positive effect of palivizumab, the small number of events rendered results inconclusive.
- Palivizumab demonstrated no significant association with reduced hospitalizations for acute respiratory illness, suggesting a limited overall effect. Younger age was a significant risk factor for infection.
Background:
Evidence on the effectiveness of respiratory syncytial virus (RSV) immunoprophylaxis with palivizumab in children with cystic fibrosis (CF) is lacking.
Methods:
We utilized Medicaid Extract files from 27 states from 1999 to 2006 linked to the National Cystic Fibrosis Registry to establish a cohort of children 0-2 years with CF diagnosis. Eligible children entered the cohort after CF diagnosis and after RSV season onset, and were followed until season end, second birthday, death, or hospitalizations for reasons other then the study outcome. Two outcomes were examined: hospitalization for RSV infections (RSV-ha), or hospitalization for acute respiratory infections (ARI-ha). Palivizumab exposure was defined based on pharmacy or procedure claims as current (claim date plus 30 days), former (day 31-60 after a claim), and no exposure (days before the first or >60 days after any claim). Both outcomes were examined in a Cox regression model, adjusting for RSV risk factors and CF severity via exposure propensity score.
Results:
The matched cohort included 1,974 infants (2,875 infant seasons), who experienced 32 RSV-ha and 212 ARI-ha (3.9 and 26.2/1,000 season months, respectively). Compared to periods of no use, the adjusted hazard ratio for current use was 0.57 (95% confidence interval [CI]: 0.20-1.60) for RSV-related hospitalization and 0.85 (95% CI: 0.59-1.21) for ARI-related hospitalization. Each month of increasing age reduced the ARI-ha by 5.8%.
Conclusion:
RSV hospitalization incidence was low suggesting either little contribution of the virus to respiratory infections in patients with CF or lack of RSV testing. Unadjusted and adjusted RSV-hospitalization incidence rates suggested potentially positive effects of palivizumab, but results were inconclusive due to small event rates. Hospitalizations for acute respiratory illness with possible RSV contribution showed no association with palivizumab use, suggesting limited overall effect of palivizumab. Younger age greatly increased infection risk.
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