SEVERITY OF RESPIRATORY SYNCYTIAL VIRUS-INFECTION INFLUENCED BY CLINICAL RISK-FACTORS AND SUBTYPE-A AND SUBTYPE-B IN HOSPITALIZED CHILDREN

Background Since it is possible to identify the subgroups of RSV, A-su btype and B-subtype, there are findings indicating that the subtype ma y influence severity of RSV infection. Our study was designed to asses s the hypothesis that A-subtype infections were more severe than B-sub type infections among hospitalized children. Patients All medical reco rds of patients hospitalized with RSV infection between March 1990 and March 1993 were reviewed. A total of 107 children with proven RSV inf ection were identified. Methods Nasal waste specimens for culture were obtained from infants with suspected RSV infection. Subtype determina tion was done on frozen virus cultures. The following risk factors wer e defined: age less than or equal to 3 months, weight < 5 kg, prematur ity and underlying cardiac or respiratory disease and immune deficienc y. To analyse the relationship between risk factors, subtype and sever ity a multivariate analysis was performed. Severity was measured by cl inical observations as following: pH, PCO2, SaO(2), oxygen supplementa tion, history of apnea and length of hospital stay. Main results Of th e enrolled patients 11 had underlying disease and 17 were premature. T he age range was 1 week to 4.2 years, median 3.5 months. 46 children w ere younger than 3 months, 33 had a weight of less than 5 kg. The isol ates of 84 children were typeable: 63 isolates were subtype A and 21 s ubtype B. Underlying disease and prematurity were associated with SaO( 2) < 87% (p =0.003) and oxygen supplementation (p = 0.017). A weight o f less than 5 kg was correlated with a PCO2 greater than or equal to 5 0 mmHg. The RSV subtype was not significantly correlated with severity . Conclusions RSV infection even in very young children is predominant ly influenced by underlying disease, prematurity and weight. The RSV s ubtype was no independent risk factor for an increased morbidity in th is retrospective study. Therefore, in our opinion, RSV subtype is less meaningful to predict the severity of RSV infection than known risk f actors.