A population based study

Abstract

To determine the morbidity and mortality from childhood Haemophilus influenzae type b (Hib) meningitis in a well defined population. Retrospective survey 1985-1987 and prospective surveillance of hospital laboratories 1989-1990. Information on outcome of meningitis was obtained from hospital records and attending physicians and, in 1989-1990, from a survey of the children's parents. Sydney Statistical Division, which had a population of children aged 0-4 years of 229,165 in 1986 and 263,758 in 1990. Eligible children were aged from one month to four years and had clinical and microbiological evidence of Hib meningitis on standard criteria. There were 229 eligible children. Twelve were excluded (seven died and five had pre-existing neurological deficits). A neurological deficit was detected at the time of hospital discharge in 45 patients (21%) and persisted for 12 months or longer in 29 patients (13%). Follow-up information was available for 165 (96%) children who were normal at the time of hospital discharge and persistent deficits were recorded in 12 (7%) of these children. Forty-one children (19%) had readily recognisable neurological or hearing problems: nine (4%) had persistent severe neurological deficits and seven (3%) had severe hearing loss requiring hearing aids or a cochlear implant. Age had a significant influence on outcome. The youngest children were significantly more likely to be admitted to intensive care. Severe neurological deficits showed a significant negative trend with increasing age (P = 0.03). Severe unilateral or bilateral sensorineural loss (odds ratio [OR] 8.0, 95% confidence interval [CI] 1.5-81) and ataxia at discharge (OR 13.3, 95% CI 2.8-128) were noticeably more common in children over two years of age, with a significant positive trend (P < or = 0.001) with increasing age. Patients requiring intensive care were much more likely to have an adverse outcome, particularly if positive pressure ventilation was needed. These data provide population-based estimates of the minimum incidence of adverse outcomes from Hib meningitis in an urban community with good access to medical services. This is important in assessing the impact of Hib vaccination, as meningitis is responsible for most of the long-term morbidity from childhood invasive Hib disease. Determination of the relationship between morbidity and age is important for assessing alternative vaccine strategies.