Assessing Clinical Improvement of Infants Hospitalized for Respiratory Syncytial Virus-Related Critical Illness

Abstract

Background: Pediatric respiratory syncytial virus (RSV)-related acute lower respiratory tract infection (LRTI) commonly requires hospitalization. The Clinical Progression Scale-Pediatrics (CPS-Ped) measures level of respiratory support and degree of hypoxia across a range of disease severity, but it has not been applied in infants hospitalized with severe RSV-LRTI.

Methods: We analyzed data from a prospective surveillance registry of infants hospitalized for RSV-related complications across 39 pediatric intensive care units in the United States from October through December 2022. We assigned CPS-Ped (0 = discharged home at respiratory baseline to 8 = death) at admission and days 2-7, 10, and 14. We identified predictors of clinical improvement (CPS-Ped ≤2 or 3-point decrease) by day 7 using multivariable log-binomial regression models and estimated the sample size (80% power) to detect 15% between-group clinical improvement with CPS-Ped versus hospital length of stay (LOS).

Results: Of 585 hospitalized infants, 138 (23.6%) received invasive mechanical ventilation (IMV) and 1 died. Failure to clinically improve by day 7 occurred in 205 (35%) infants and was associated with age <3 months, prematurity, underlying respiratory condition, and IMV in the first 24 hours in the multivariable analysis. The estimated sample size per arm required for detecting a 15% clinical improvement in a potential study was 584 using CPS-Ped clinical improvement versus 2031 for hospital LOS.

Conclusions: CPS-Ped can be used to capture a range of disease severity and track clinical improvement in infants who develop RSV-related critical illness and could be useful for evaluating therapeutic interventions for RSV.

Keywords: acute hypoxic respiratory failure; acute respiratory distress syndrome; intensive care unit; outcome; pediatric.

Figure 1.

Distribution of the Clinical Progression Scale–Pediatrics (CPS-Ped) by hospital day through day 14. Infants are color-coded by CPS-Ped on admission (hospital day 1) and days 2–7, 10, and 14. The legend includes the score definitions for CPS-Ped. ^aPediatric acute respiratory distress syndrome definitions based on the Second Pediatric Acute Lung Injury Consensus Conference [24]. Formulas: oxygenation index = (fraction of inspired oxygen [FiO₂] × mean airway pressure × 100) / partial pressure of oxygen; oxygenation saturation index = (FiO₂ × mean airway pressure × 100) / oxygen saturation. ^bNew respiratory support includes infants who are discharged from the hospital on new oxygen, new noninvasive positive pressure ventilation, or new ventilator dependence. Abbreviations: HFNC, high-flow nasal cannula; IMV, invasive mechanical ventilation; NIPPV, noninvasive positive pressure ventilation; PARDS, pediatric acute respiratory distress syndrome.

Figure 2.

Predictors of failure to clinically improve by day 7. Clinical improvement was defined as Clinical Progression Scale–Pediatrics (CPS-Ped) of ≤2 or a decrease from maximum score by 3 points at day 7. *Clinically significant results. Abbreviations: CI, confidence interval; PR, prevalence ratio.