COMPREHENSIVE ANALYSIS OF RISK-FACTORS FOR ACQUISITION OF PSEUDOMONAS-AERUGINOSA IN YOUNG-CHILDREN WITH CYSTIC-FIBROSIS

The objective of this study was to identify risk factors of significan ce for acquisition of Pseudomonas aeruginosa by children with cystic f ibrosis (CF). Our working hypothesis is that exposure of infants and y oung children with CF to older, infected patients increases their risk for acquiring this organism. A special opportunity arose to study thi s question in detail, as we have been performing a randomized clinical trial of neonatal screening for CF throughout the state of Wisconsin during the period of 1985-1994. Patients were selected for this study based on either early identification through screening or diagnosis by standard methods. A longitudinal protocol employed at Wisconsin's two CF Centers includes routine cultures of respiratory secretions and co llection of clinical, demographic, and activity information on patient s and their families. Previous observations in our trial revealed that one center at an old hospital in an urban location showed a significa ntly shorter time to acquisition of P, aeruginosa for CF patients foll owed there. To study the center effect further, we performed statistic al analyses using survival curves and stepwise regression analysis of all life history covariates available. The results of these analyses s howed that the statistically significant correlations involve the foll owing risk factors: 1) center and old hospital (r = 0.42); 2) center a nd original physician (r = 0.61); 3) center and exposure to pseudomona s-positive patients (r = 0.29); and 4) population density and urban lo cation (r = 0.49). The final statistical model demonstrated that incre ased risk due to aerosol use (odds ratio = 3.45, P = 0.014) and a prot ective effect associated with education of the mother (odds ratio = 0. 81, P = 0.024) were the most significant factors for acquisition of P, aeruginosa. The previously observed center effect was confined to the 1985-1990 interval at the old hospital (odds ratio = 4.43, P < 0.001) . We conclude that multiple factors are involved in increasing the ris k of young children with CF to acquire P. aeruginosa, and that the obs erved center effect can best be explained by a combination of factors. These results suggest that facilities and methods used to care for yo ung children with CF can significantly influence their likelihood of a cquiring pseudomonas in the respiratory tract. Pediatr Pulmonol. 1998; 26:81-88. (C) 1998 Wiley-Liss, Inc.