CHANGING TRENDS IN THE EPIDEMIOLOGY AND PATHOGENESIS OF NEONATAL CHRONIC LUNG-DISEASE

Objective: To assess the role of specific risk factors that may predis pose preterm infants with mild or no initial respiratory distress synd rome to the development of chronic lung disease (CLD). Study design: C linical data were collected prospectively from 119 ventilator-supporte d preterm infants with birth weights between 500 and 1000 gm, who surv ived more than 28 days and required fewer than 3 days of treatment wit h fraction of inspired oxygen > 25% during the first 5 days of life. L ogistic regression analysis was used in a multivariate assessment of r isk factors for CLD. Results: Chronic lung disease occurred in 44 of t he patients (37%). The analysis showed that low birth weight, patent d uctus arteriosus (PDA), and sepsis were significant risk factors for C LD. The corresponding odds ratios for CLD and their 95% confidence int ervals (CI) were as follows: 2.9 per 100 gm birth weight decrement (CI , 1.7 to 4.8); 6.2 (CI, 2.1 to 18.4) for PDA; and 4.4 (CI, 1.3 to 14.5 ) for sepsis. When sepsis and PDA occurred simultaneously, the odds ra tio for CLD increased to 48.3 (CI, 6.3 to >100) in comparison with inf ants without these conditions. Episodes of PDA were categorized as eit her early (occurring during the first week of life) or late (after the first week), and the respective odds ratios for CLD were 2.8 (CI, 0.8 to 9.4) and 21.1 (CI, 5.6 to 80) in comparison with infants without P DA. For the duration of symptomatic PDA, the odds ratio for CLD was 3. 5 per week that the PDA remained open (CI, 1.9 to 6.5). Conclusion: CL D is a frequent sequela in very low birth weight infants with mild or no respiratory distress syndrome. In this population, the development of late episodes of PDA, usually in association with a nosocomial infe ction, seems to play a primary role in the pathogenesis of CLD.