Dear Editor,

We read with interest the study by Heikkinen et al [1] and the letter by Bala, Ryan and Murphy [2] on bronchiolitis hospital admissions and of Palivizumab prophylaxis. We would like to add our experience on the issue.

Our retrospective study covered the period from 01.01.1995 to 31.12.2000 i.e. a 6-year period before Palivizumab prophylaxis became available in Greece. We looked into hospital admissions with the clinical diagnosis of bronchiolitis of infants born less than 32 weeks of gestation within one year after discharge from our NICU. We did not specifically look for RSV diagnosis as in Greece rapid laboratory testing for this virus became widely available as late as 1999. Information was collected and analysed using NICU and follow up medical notes; medical notes of the hospital the infants were admitted in case of bronchiolitis as well as parental questionnaire and direct telephone contact.

During the study period 289 infants were discharged and 5 deaths (1.7%) occurred following discharge, all unrelated to respiratory disease. Of the remaining 284 infants, 242 (85%) were traced and were included in this analysis. The median gestational age was 29 weeks (24-31 weeks) and the median birthweight was 1200g (550-1810g). Mechanical ventilation received 161 (66.5%) and oxygen administration at 36 weeks required 11 (4.5%). No infant was discharged home on oxygen. Total admissions to hospital within one year of discharge involved 56 infants (23.1%), while 25 (10.3%) were admitted with the clinical diagnosis of bronchiolitis. None of these infants required intensive care including mechanical ventilation and the median length of hospitalisation was 7 days (5-14 days). There were no deaths.

Using logistic regression analysis of probable factors influencing bronchiolitis hospital admission revealed that the presence of older siblings at home significantly increased the chance of admission (OR 5.5 95%CI 2.69 13.82, p <_0.001 particularly="particularly" if="if" the="the" older="older" sibling="sibling" was="was" attending="attending" nursery="nursery" or="or" school="school" _6.25="_6.25" _95ci="_95ci" _2.63="_2.63" _16.67="_16.67" p0.001.="p0.001." eighty="eighty" percent="percent" of="of" _25="_25" infants="infants" had="had" siblings.="siblings." no="no" association="association" found="found" with="with" other="other" factors="factors" such="such" as="as" peri="peri" neonatal="neonatal" gestational="gestational" age="age" birthweight="birthweight" prenatal="prenatal" administration="administration" steroids="steroids" mechanical="mechanical" ventilation="ventilation" surfactant="surfactant" oxygen="oxygen" dependency="dependency" at="at" _28="_28" days="days" _36="_36" weeks="weeks" maternal="maternal" milk="milk" family="family" history="history" asthma="asthma" parental="parental" smoking="smoking" pet="pet" in="in" household="household" sleeping="sleeping" arrangement.="arrangement." p="p"> Since no information regarding RSV infection was available we hypothesised that all episodes of bronchiolitis necessitating admission to hospital were due to RSV. Using American Academy recommendations [3] and the results of the Impact Study [4], prophylaxis of 17.1 infants with the monoclonal antibody (Palivizumab) would be required to avert 1 hospital admission. It was estimated that Palivizumab prophylaxis would reduce hospital costs by 29400€ but would have cost 575000€. Prophylaxis of the infants with older sibling(s) i.e. 36% of 242 infants of this study would have included 20 out of 25 hospitalised infants (80%) because of bronchiolitis. We entirely endorse the conclusions by Heikkinen et al [1] and Bala et al [2]

References

(1). Heikkinen T, Valkonen H, Lehtonen L et al. Hospital admission of high risk infants for respiratory syncytial virus infection: implications for palivizumab prophylaxis. Arch Dis Child Fetal Neonatal Ed 2005; 90:F64 -F68

(2). Bala P, Ryan CA, Murphy BP. Hospital admissions for bronchiolitis in preterm infants in the absence of respiratory syncytial virus prophylaxis. Arch Dis Child Feta Neonatal Ed 2005;90:92

(3). American Academy of Pediatrics. Prevention of respiratory syncytial virus infections: indications for the use of palivizumab and update on the use of RSV-IGIV. Pediatrics 1998;102:1211-16

(4). The Impact-RSV Study Group. Palivizumab, a humanized respiratory syncytial virus monoclonal antibody, reduces hospitalisation from respiratory syncytial virus infection in high risk infants. Pediatrics 1998;102:531-7