Morbidity patterns of extremely preterm infants: Relationships with respiratory outcome, growth achievement, and family impact during the first two years of life.

Abstract

Extremely low birth weight (ELBW; $<$1251 g) infants exhibit varying degrees of illness severity and stability. Most measures that assess morbidity, or illness, are static and evaluate infant status at a single time point or by creating summary scores. An alternative approach is presented. This study examined daily fluctuation of illness severity (i.e., morbidity pattern) over the first 6 weeks of life for 76 ELBW infants. Three groups of infants were identified: "well" infants (42.1%) had patterns of quick stabilization to low illness severity levels, "sick" infants (47.7%) exhibited patterns of recovery to moderate but varying levels of illness severity, and "unstable" infants (10.5%) demonstrated patterns that were highly unstable. Relationships of morbidity pattern with respiratory outcome, growth achievement, and family impact at 8 and 19 months corrected age were evaluated for 55 of these infants. Patterns predicted respiratory outcome at 8 months (p =.0067). Pattern and birth weight (BW) predicted outcome at 19 months (p =.0157). Although all infants had respiratory distress syndrome (RDS), and 57% had bronchopulmonary dysplasia (BPD) at term age, only 11.5% had moderate/severe respiratory status at 19 months. Patterns did not predict growth achievement. By 19 months, 74% of infants had lengths $\geq$25th percentile. In contrast, 63% had weights and 59% had head circumferences $<$25th percentile. Of concern, 31% (n = 16) were microcephalic ($<$5th percentile) at 19 months. BW was a significant predictor of head growth at 19 months (p =.0057). Patterns explained moderate levels of variance in maternal reports of impact on family (n = 32) at discharge, 8, and 19 months. Infant morbidity patterns were related to patterns of impact. Mothers of "unstable" infants reported decreasing impact that coincided with increasing social support and decreasing financial burden. Mothers of "sick" infants reported less impact than mothers of "unstable" or "well" infants at discharge and 8 months. All mothers reported similar levels of impact by 19 months, although levels of impact increased from discharge to 19 months. These findings are discussed in relation to stress and coping, social comparison theory, and transitions of development.