Respiratory syncytial virus morbidity, premorbid factors, seasonality, and implications for prophylaxis

Abstract

Objectives: We investigated factors associated with morbidity and pediatric intensive care unit (PICU) admission in children with respiratory syncytial virus (RSV) infection and explored seasonality and implication of prophylaxis.

Methods: A retrospective study between 2006 and 2008 of every child with a laboratory-confirmed RSV infection was included.

Results: Six hundred seventy RSV admissions were identified. Ten (1.5%) required PICU admissions. Children admitted to PICU were younger than non-PICU admissions (median [interquartile range] age, 0.3 [0.11-0.48] vs 1.18 [0.46-2.49] years; P = .001). Odds associated with PICU admissions included history of chronic lung disease (odds ratio [95% confidence interval], 18.08 [2.29-114.95]; P = .010), history of acyanotic heart disease (7.61 [1.04-42.59], P = .043), and neurodevelopmental conditions (mental retardation, cerebral palsy, or neuromuscular disease; 8.41 [1.63-38.57], P = .012). Odds of bacterial coinfections was 13.50 (1.77-81.29), P = .017. There appeared no significant PICU predilection in terms of sex, history of prematurity, cyanotic heart disease, seizure disorders, chromosomal disorders, or malignancy. Admissions associated with proven RSV infections accounted for 2.4% of PICU annual admissions. The duration of PICU stay was generally brief (median, 3 days). However, median length of hospital stay was significantly longer in the PICU category (8.5 vs 3 days, P < .001). There was no death in the study period. Only 5 (0.75%) of 665 patients were readmitted to the pediatric infectious disease isolation ward in consecutive years, and none required PICU support. Twenty (3%) of admissions involved neonates younger than 30 days. There was no definite seasonality, but incidence was lowest between October and January.

Conclusions: Most infants have mild disease and do not require PICU support. Young infants with history of chronic lung disease, congenital heart disease, and neurodevelopmental conditions appear to be at significantly increased risk for PICU support. There is no winter seasonality for RSV disease in Hong Kong. Therefore, any prophylaxis for at-risk population should provide adequate coverage for the warmer months in subtropical regions.