Objective: To evaluate the relationship between maternal self-reported race/ethnicity and persistent wheezing illness in former high-risk, extremely low gestational age newborns, and to quantify the contribution of socioeconomic, environmental, and biological factors on this relationship. Study design: We assessed persistent wheezing illness determined at 18-24 months corrected (for prematurity) age in survivors of a randomized trial. Parents/caregivers were surveyed for wheeze and inhaled asthma medication use quarterly to 12 months, and at 18 and 24 months. We used multivariable analysis to evaluate the relationship of maternal race to persistent wheezing illness, and identified mediators for this relationship via formal mediation analysis. Results: Of 420 infants (25.2 ± 1.2 weeks of gestation and 714 ± 166 g at birth, 57% male, 34% maternal black race), 189 (45%) had persistent wheezing illness. After adjustment for gestational age, birth weight, and sex, infants of black mothers had increased odds of persistent wheeze compared with infants of nonblack mothers (OR = 2.9, 95% CI 1.9, 4.5). Only bronchopulmonary dysplasia, breast milk diet, and public insurance status were identified as mediators. In this model, the direct effect of race accounted for 69% of the relationship between maternal race and persistent wheeze, whereas breast milk diet, public insurance status, and bronchopulmonary dysplasia accounted for 8%, 12%, and 10%, respectively. Conclusions: Among former high-risk extremely low gestational age newborns, infants of black mothers have increased odds of developing persistent wheeze. A substantial proportion of this effect is directly accounted for by race, which may reflect unmeasured environmental influences, and acquired and innate biological differences. Trial registration: ClinicalTrials.gov: NCT01022580.
Bibliographical noteFunding Information:
TOLSURF was funded through cooperative agreements with NHLBI (U01 HL094338 and U01 HL094355). Consistent with this, Dr Carol Blaisdell, the NHLBI Scientific Officer and an employee of NHLBI was present and participated in all TOLSURF Steering Committee meetings as a nonvoting member. K.W. was supported by the National Center for Advancing Translational Sciences, National Institutes of Health, through UCSF-CTSI (UL1 TR000004). ONY, Inc provided Infasurf and IKARIA, Inc provided inhaled nitric oxide and its delivery system for the conduct of the TOLSURF. Neither company was involved in study design, data collection, analysis or interpretation, manuscript writing, or the decision to submit any manuscript for publication. The authors declare no conflicts of interest.
- socioeconomic factors