A multilevel proportional hazards model was used to determine the prognostic factors affecting hospitalisations for recurrent diarrhoeal disease in infants and young children. All infants born in 1996 who had index gastroenteritis admission to Western Australian (WA) hospitals during their first year of life were included in our study cohort (n = 486). There were 618 hospital admissions for infectious diarrhoea over the 6-year follow-up period. Aboriginal children stayed significantly longer in hospital than their non-Aboriginal peers, and comorbidities such as dehydration, gastrointestinal sugar intolerance, failure to thrive, iron deficiency anaemia and certain infections (genitourinary, scabies and/or otitis media) were all significantly associated with the delayed discharge of patients. Substantial variations among patients (variance = 0.660) and between health service regions of WA (variance = 0.296) were found. Over 30% of the total variation could be attributed to the heterogeneity between health districts. For any two patients in the same health district, the within-region (intraclass) correlation was estimated to be 0.309.
In the absence of detailed socio-demographic data, application of the standard survival procedure may lead to incorrect inferences due to regional clustering and repeated observations on individuals. By accounting for latent patient and regional effects, the multilevel analysis clearly confirmed the high burden of infectious diarrhoea among Aboriginal infants and children, and their much longer hospital stays. Coexisting morbidities contributed to the prolonged and recurrent hospitalisations. Findings of this epidemiological study indicated the need of multifaceted clinical disease prevention and hygiene promotion strategies to control the disease.