Decline of pediatric admissions with Haemophilus influenzae type b in New York State, 1982 through 1993: relation to immunizations.

OBJECTIVES: To evaluate the impact of vaccination for Haemophilus influenzae type b (Hib) on pediatric hospital admissions in New York State, and to identify risk factors in children who continue to be admitted for Hib invasive disease. METHODS: Retrospective review of hospitalizations in New York state from 1982 through 1993 and a survey of immunization records from physician offices in Monroe Country, New York. RESULTS: In 1982, 769 children were admitted to New York state hospitals for Hib-related conditions; by 1993, this had decreased to 133. Significant declines during the study period occurred in the age-adjusted admission rates for Hib meningitis, septicemia, pneumonia, and epiglottitis, but not for arthritis and osteomyelitis. In 1993 alone, 712 admissions, 18 deaths, and 135 episodes of morbidity were avoided. Since 1991, the rates of admissions for Hib-related conditions have remained fairly constant. Minority subjects continue to be twice as likely as white subjects to be admitted for invasive Hib disease (0.44 vs 0.17/100,000). Children living in urban Rochester also are more likely to be admitted and less likely to be completely immunized against Hib (61%) than those living in suburban areas (82%). CONCLUSIONS: Although Hib vaccine has had a major impact on hospital admissions for Hib-related conditions, the goal of completely eliminating Hib disease will require programs targeted at groups at high risk, such as minorities and those living in cities.

Hospitalization for lower respiratory tract illness in infants: variation in rates among counties in New York State and areas within Monroe County.

OBJECTIVE: Lower respiratory tract illness (LRI) is the most common serious illness in childhood and the most common reason for hospitalization of infants beyond the neonatal period. This study assessed the potential for cost savings from reduction in hospitalization for LRI. SETTING AND SAMPLE: LRI hospitalization rates for children in the first 2 years of life (infants) were studied for the 62 counties of New York State and six socioeconomic areas within Monroe County (Rochester) for the years 1985 through 1991. DESIGN: Analysis of small area variations. RESULTS: LRI accounted for 51.2% of infant hospitalizations in New York State. The overall LRI hospitalization rate for New York's 62 counties was 27.0 per 1000 child-years and ranged, among the 18 most populous counties, from 10.7 for Monroe County to 39.3 for the Bronx. Unemployment rate was the strongest predictor of LRI hospitalization rates for counties, explaining 29% of the variance in multiple regression analysis. Within Monroe County, LRI hospitalization rates followed a geographic gradient from the inner city (22.5) to the rest of the city (12.2), and to the suburbs (7.3). Deaths from LRI were uncommon (0.36% of state LRI hospitalizations) and varied little between inner city (0.42%) and suburbs (0.51%). If LRI hospitalization rates for Monroe County suburban children prevailed for the entire state, 10,439 hospitalizations and $32,916,000 would be saved annually. CONCLUSIONS: A large portion of the increased cost of health care for children living in poverty is attributable to hospitalization for LRI in infants. Physician discretion in decision making and factors associated with socioeconomic status are probably major determinants of variation. Well-coordinated follow-up of acute illness visits, home monitoring by visiting nurses, and empirically based clinical guidelines for management of LRI might yield both substantial cost savings and better service to families.

Variation in severity of respiratory syncytial virus infections with subtype.

Two major subtypes of respiratory syncytial virus have been identified. This study assessed the hypothesis that A-subtype infections were more severe than B-subtype infections among the 157 infants hospitalized in two hospitals in Rochester, N.Y., during two winters. Severity was measured both by specific clinical observations and by a severity index that was derived empirically. Among all subjects, several clinical observations suggested that A-subtype infections were more severe. For example, mechanical ventilation was required in 12.6% of those with A-subtype compared with 1.6% of those with B-subtype infection (relative risk = 7.88; p = 0.01). Among high-risk infants (infants with underlying conditions or age 3 months or less at admission), carbon dioxide tension greater than 45 mm Hg was found in 37.0% of those with A-subtype compared with 12.0% of those with B-subtype infection (relative risk = 3.08; p = 0.04). In discrete multivariate (logit) analysis, effects of subtype (odds ratio = 6.59; p less than 0.01) on severity remained after adjustment for other statistically significant effects of age less than 3 months, underlying condition, and premature birth. The finding that A-subtype infections were more severe might have important implications for vaccine development, studies of the virulence of respiratory syncytial virus, clinical management (e.g., selection for antiviral therapy), and long-term prognosis.

Normal pulmonary function measurements and airway reactivity in childhood after mild bronchiolitis.

Concern about the long-term sequelae of bronchiolitis has been raised through studies of children hospitalized for bronchiolitis, but the long-term sequelae of mild bronchiolitis have not been studied. We assessed the hypothesis that 25 children with mild bronchiolitis (index subjects) were at greater risk for abnormalities of pulmonary function or airway reactivity to cold air between the ages of 8 and 12 years than were randomly selected, matched controls. There were no consistent differences in pulmonary function or airway reactivity between index and control groups. Airway hyperreactivity was found in five control subjects and three index subjects, and all children with symptomatic asthma were identified by cold air challenge. Our data suggest that children with a history of mild bronchiolitis are not at increased risk between ages 8 and 12 years for airway hyperreactivity or for abnormalities in pulmonary function.