Real-world Associations of US Cystic Fibrosis Newborn Screening Programs With Nutritional and Pulmonary Outcomes

Abstract

Importance: Newborn screening (NBS) for cystic fibrosis (CF) has been universal in the US since 2010, but its association with clinical outcomes is unclear.

Objective: To describe the real-world effectiveness of NBS programs for CF in the US on outcomes up to age 10 years.

Design, setting, and participants: This was a retrospective cohort study using CF Foundation Patient Registry data from January 1, 2000, to December 31, 2018. The staggered implementation of NBS programs by state was used to compare longitudinal outcomes among children in the same birth cohort born before vs after the implementation of NBS for CF in their state of birth. Participants included children with an established diagnosis of CF born between January 1, 2000, to December 31, 2018, in any of the 44 states that implemented NBS for CF between 2003 and 2010. Data were analyzed from October 5, 2020, to April 22, 2022.

Exposures: Birth before vs after the implementation of NBS for CF in the state of birth.

Main outcomes and measures: Longitudinal trajectory of height and weight percentiles from diagnosis, lung function (forced expiratory volume in 1 second, [FEV1] percent predicted) from age 6 years, and age at initial and chronic infection with Pseudomonas aeruginosa using linear mixed-effects and time-to-event models adjusting for birth cohort and potential confounders.

Results: A total of 9571 participants (4713 female participants [49.2%]) were eligible for inclusion, with 4510 (47.1%) in the pre-NBS cohort. NBS was associated with higher weight and height percentiles in the first year of life (weight, 6.0; 95% CI, 3.1-8.4; height, 6.6; 95% CI, 3.8-9.3), but these differences decreased with age. There was no association between NBS and FEV1 at age 6 years, but the percent-predicted FEV1 did increase more rapidly with age in the post-NBS cohort. NBS was associated with older age at chronic P aeruginosa infection (hazard ratio, 0.69; 95% CI, 0.54-0.89) but not initial P aeruginosa infection (hazard ratio, 0.88; 95% CI, 0.77-1.01).

Conclusions and relevance: NBS for CF in the US was associated with improved nutritional status up to age 10 years, a more rapid increase in lung function, and delayed chronic P aeruginosa infection. In the future, as highly effective modulator therapies become available for infants with CF, NBS will allow for presymptomatic initiation of these disease-modifying therapies before irreversible organ damage.

Figure 1.. Consolidated Standards of Reporting Trials (CONSORT) Diagram and Year of Newborn Screening (NBS) Implementation

A, The CONSORT diagram shows the number of participants for each study outcome presented along with the total participants excluded. B, NBS chart displays the year in which cystic fibrosis screening was initiated for each state. FEV₁ indicates forced expiratory volume in the first second of expiration. ^aStates excluded from analysis.

Figure 2.. Association of Newborn Screening (NBS) With Observed Height and Weight Percentile and Forced Expiratory Volume in the First Second of Expiration (FEV₁) Predicted by Age and on Marginal Mean Predictions From Mixed-Effects Models

Box plots showing the distribution of observed data by age and the marginal mean prediction (and 95% CIs) between age and weight (A), height (B), and FEV₁ (C) from linear mixed-effects models with random intercepts for state and child. Predictions and 95% CIs are weighted by the distribution of the other independent variables (ie, birth cohort, insurance, sex, CFTR functional class).