Risk factors for pediatric invasive pneumococcal disease in the intermountain West, 1996-2002

PURPOSE: In response to concerns that the epidemiology of pediatric invasive pneumococcal disease (IPD) in the Intermountain West (i.e., Utah, Idaho, Wyoming, Montana, and parts of Arizona and Nevada) was poorly understood and might differ from elsewhere in the United States, a case-control study was undertaken to determine factors associated with IPD during 1996-2002. METHODS: A telephone questionnaire was administered to parents of children comprising 120 cases identified through hospital records and to parents of 156 age-matched controls located by random-digit di- aling. The unit of analysis was each matched case-control set. RESULTS: Underlying chronic illness was reported for 32 (27%) of the cases. For previously healthy children, breastfeeding had a protective benefit (adjusted odds ratio: 0.2; 95% confidence interval [CI] 0.1-0.6), while a history of tympanostomy tube surgery was a risk factor (adjusted odds ratio: 12.6; 95% Cl, 1.5-107.3). CONCLUSIONS: The presence of an underlying chronic illness was the strongest risk factor for IPD. Except for a history of tympanostomy tube surgery, the factors associated with IPD in this investigation were similar to those reported from other geographic regions. Tympanostomy surgery might serve as a surrogate indicator for predisposition to recurrent otitis media or decreased ability to clear pneumococcal infection, raising risk for invasive disease. Pediatric clinicians should continue to encourage breastfeeding, and continued emphasis on pneumococcal vaccination should help prevent IPD.