Morbidity and mortality after RSV-associated hospitalizations among premature Canadian infants

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Abstract

Objective

To evaluate the impact of respiratory syncytial virus (RSV) infections on subsequent health care resource utilization in preterm infants.

Study design

Analysis of data from 2415 preterm infants (32 to 35 weeks gestational age [GA]) hospitalized for proven or probable RSV and matched to 20,254 control infants.

Results

Mean (SD) age at the index admission was 7.7 (5.5) months; 46% of the infants were male. Mean (SD) subsequent health services, excluding the index event, for the RSV cohort and control infants, respectively, were hospitalization, 2.96 (2.81) versus 1.28 (1.42); special care unit visits, 0.67 (1.70) versus 0.40 (0.33); respiratory therapy visits, 0:31 (0.70) versus 0.13 (0.37); physician consults, 3.61 (4.54) versus 0.89 (1.12); in-hospital procedures, 1.05 (4.02) versus 0.81 (1.51); outpatient visits, 18.4 (10.58) versus 7.54 (4.31); and mean (SD) inpatient days, 14.71 (18.69) versus 5.04 (7.09). All differences were statistically significant (P<.001). Diagnoses for the RSV and control cohorts were respiratory conditions (64% versus 13%), fever (2.7% versus 0.7%), anorexia (2.2% versus 0.6%), lack of normal physiological development (2.8% versus 1.1%; P<.05), overall deaths (8.1% versus 1.6%; P<.001), and sudden death (6.1% versus 0.3%; P<.001).

Conclusions

RSV hospitalization in healthy premature infants is associated with a significant increase in subsequent health care resource utilization and mortality. Results support prophylaxis of premature infants against RSV hospitalization.

Section snippets

Methods

Data for this study were obtained from the Canadian Institute of Health Information (CIHI): Discharge Abstract Database (DAD) and Hospital Morbidity Database (HMD). These databases capture all hospital separations including transfers, discharges, and deaths, with data on a per-patient basis that describe all elements of in-hospital care. The preterm infant cohort consisted of infants born between 1997 and 2000 at 32 to 35 weeks gestation, who were identified on the basis of the International

Results

A total of 2415 infants with RSV hospitalizations were identified. Of these, 2149 (88.9%) were hospitalized for probable RSV bronchiolitis, 114 (4.8%) for probable RSV pneumonia, and 152 (6.3%) for confirmed RSV pneumonia or bronchiolitis. The study included 20,254 matched control infants; 46% male and 54% female infants. The mean (SD) age at the index admission was 7.7 (5.5) months, with a range of 0.5 to 11.2 months and a median of 6.9 months. The mean duration of follow-up since the index

Discussion

There is strong evidence that preterm infants are at high risk for several chronic and acute conditions.1., 2., 3., 4., 5. Preterm infants are at increased risk of RSV infections severe enough to lead to hospitalization, and these infections and hospitalizations are potentially preventable.10., 11., 12., 13., 14., 15., 16., 17., 18., 19., 20., 21., 22., 23. Results from several studies show that prophylaxis with palivizumab (Synagis), a humanized immunoglobulin, monoclonal antibody, is safe and

Conclusions

Severe RSV infections leading to hospitalization in 32 to 35 weeks GA preterm infants are associated with an increased rate of morbidity, mortality, and health care use for respiratory conditions during the 1 to 4 years subsequent to the index infection. The results of our study identified an important signal regarding the impact of RSV infections on nonrespiratory morbidity and mortality that requires further investigation.

John V. Williams, MD, Pediatric Infectious Diseases, Vanderbilt University Medical Center, Nashville, Tenn:

In terms of your finding of a greater occurrence of fever in the follow-up period in infants hospitalized for RSV, I can't think of a biological explanation for recurrent fever after primary RSV infection. This suggests that there are in fact differences between the populations that are not apparent at first glance.

Dr Sampalis:

We removed from analysis all children with congenital abnormalities or any other chronic condition that might predispose them to hospitalizations, particularly for respiratory

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