HOSPITALIZATION FOR LOWER RESPIRATORY-DISEASE DURING 20 YRS AMONG UNDER 5 YR OLD CHILDREN IN STOCKHOLM COUNTY - A POPULATION-BASED SURVEY

Lower respiratory disease (LRD) is a common cause of hospitalization i n infants, and episodes of obstructive LRD increase the risk for asthm a later in life, The purpose of this study was to assess time trends a nd geographical variation of first time hospitalization for LRD among children in Stockholm County, Sweden. Data on first time admittance fo r LRD among children aged up to 5 yrs from 1973 through 1992 were obta ined from the Stockholm County Council hospital discharge register, an d population register data were used for estimation of the population at risk, Municipal data were available for 1982-1992 on outbreaks of r espiratory syncytial virus (RSV) infections and socio-economic factors . A total of 12,450 children had been hospitalized for the first time with LRD, For children aged <2 yrs a 100% increase in the rate of firs t time hospitalization for LRD was observed during the study period an d children aged up to 1 yr predominated (50%). The average yearly incr ease in the population based first time hospital admission rate for LR D was 1.82%. Males constituted 65% of the cases, Of the diagnoses, 89. 6% were consistent with obstructive LRD, e.g. asthma and obstructive b ronchitis, In children aged up to 1 yr, peaks in the rate of hospitali zation tended to coincide with outbreaks of RSV infections, Difference s in hospitalization between municipalities seemed to be partly explai ned by differences in the admission practices of the four paediatric h ospitals in the area. We conclude that the increased rate of hospitali zation for lower respiratory disease in infants of Stockholm County ma y reflect a true increase in the incidence of obstructive respiratory disease, However, several factors determine admittance to hospital and the results need to be interpreted with caution.