Neonatal screening for cystic fibrosis does not affect time to first infection with Pseudomonas aeruginosa

Newborn Screening for CF across the Globe-Where Is It Worthwhile?

Newborn screening (NBS) for cystic fibrosis (CF) has been performed in many countries for as long as four decades and has transformed the routine method for diagnosing this genetic disease and improved the quality and quantity of life for people with this potentially fatal disorder. Each region has typically undertaken CF NBS after analysis of the advantages, costs, and challenges, particularly regarding the relationship of benefits to risks. The very fact that all regions that began screening for CF have continued their programs implies that public health and clinical leaders consider early diagnosis through screening to be worthwhile. Currently, many regions where CF NBS has not yet been introduced are considering options and in some situations negotiating with healthcare authorities as policy and economic factors are being debated. To consider the assigned question (where is it worthwhile?), we have completed a worldwide analysis of data and factors that should be considered when CF NBS is being contemplated. This article describes the lessons learned from the journey toward universal screening wherever CF is prevalent and an analytical framework for application in those undecided regions. In fact, the lessons learned provide insights about what is necessary to make CF NBS worthwhile.

Clinical outcomes in U.S. infants with cystic fibrosis from 2001 to 2012

BACKGROUND

All 50 United States implemented newborn screening (NBS) for cystic fibrosis (CF) by 2010. The purpose of this study was to evaluate trends over the decade when NBS became universal to determine current rates of malnutrition, stunting, and infection rates in U.S. infants with CF.

METHODS

Annual data were obtained on infants with CF up to 24 months of age diagnosed between 2001 and 2010 in the CF Foundation Patient Registry (CFFPR), in both the years of and after diagnosis, including method of diagnosis, demographics, and growth parameters and microbiology.

RESULTS

Data were obtained on 8178 infants diagnosed with CF. The percentage of infants diagnosed by NBS increased from 15% in 2001-83% in 2012 (P < 0.001). Mean weight, length, and weight-for-length z-scores in the year of diagnosis increased from 2001 to 2012 (Wt z-score 2001: -1.32 (SD 1.41), 2012: -0.72 (SD 1.12); Ht z-score 2001: -1.32 (SD 1.57), 2012 -0.60 (SD 1.21); Wt/Ht Z score 2001: -0.54 (SD 1.18), 2012: 0.06 (SD 1.05); P < 0.001 for each). The proportion of infants on pancreatic enzymes decreased from 94% in 2001-83% in 2012 (P < 0.0001). Pseudomonas aeruginosa culture positivity in the diagnosis year decreased significantly (27% in 2001, 15% in 2012, P < 0.001).

CONCLUSIONS

Nationwide implementation of CF NBS is temporally associated with significant improvements in growth outcomes and reductions in P. aeruginosa infections. Current rates of malnutrition, stunting, and airway infection present a target for early intervention and quality improvement efforts.

Transcriptional Regulation of the First Cell Fate Decision

Understanding how the first cell fate decision has chosen is a fascinating biological question that was received consider attention over the last decade. Numerous transcription factors are required, and many have been shown to have essential roles in this process. Here we reexamine the function that transcription factors play primarily in the mouse-the model system most thoroughly examined in this process. We address how the first embryonic lineage is established and maintained, with a particular emphasis on subsequent trophectoderm development and the role of the recently established Arid3a transcription factor in this process. In addition, we review relevant aspects of embryonic stem cell reprogramming into trophoblast stem cells -the equivalent of the epiblast (inner cell mass) and the establishment of induced trophoblast stem cells-the in vitro equivalent of the trophectoderm.

Risk stratification model to detect early pulmonary disease in infants with cystic fibrosis diagnosed by newborn screening

OBJECTIVE

The clinical benefit of newborn screening (NBS) for cystic fibrosis (CF) has been primarily nutritional, with less overt respiratory impact. Identification of risk factors for infant CF lung disease could facilitate targeted interventions to improve pulmonary outcomes.

METHODS

This retrospective study evaluated socioeconomic information, clinical data, and results from routine infant pulmonary function testing (iPFT) of infants diagnosed with CF through NBS (N = 43) at a single CF center over a 4-year period (2008-2012). A five-item composite clinical score was developed and combined with socioeconomic indicators to facilitate identification of CF infants at increased risk of early-onset respiratory impairment.

RESULTS

Paternal education was positively associated with lung function (P = 0.02). Clinical score <7 (on a scale of 0-10) predicted diminished pulmonary measure (P < 0.005). Retrospective risk stratification by clinical score and paternal education identified CF infants at low, intermediate, or high risk of pulmonary disease. Forced expiratory volume (FEV_0.5 %, mean ± SD) averaged 115 ± 19% in the low-risk group, 97 ± 17% in the intermediate-risk group, and 90 ± 8% in the high-risk group (P < 0.005). Results were similar for mid-expiratory flows (FEF_25-75 %). Multiple regression analysis confirmed the predictive value of this risk stratification model of CF infant pulmonary health.

CONCLUSION

We combined socioeconomic and clinical data to risk-stratify CF infants for early-onset lung disease as quantified by iPFT. Our model showed significant differences in infant pulmonary function across risk groups. The developed tool offers an easily available, inexpensive, and non-invasive way to assess risk of respiratory decline in CF infants and identify those meriting targeted therapeutic attention. Pediatr Pulmonol. 2016;51:1168-1176. © 2016 Wiley Periodicals, Inc.

Onset of persistent pseudomonas aeruginosa infection in children with cystic fibrosis with interval censored data

Background

Persistent Pseudomonas aeruginosa (PPA) infection promotes lung function deterioration in children with cystic fibrosis (CF). Although early CF diagnosis through newborn screening (NBS) has been shown to provide nutritional/growth benefit, it is unclear whether NBS lowers the risk of PPA infection and how the effect of NBS vary with age. Modeling the onset age of PPA infection is challenging because 1) the onset age of PPA infection is interval censored in patient registry data; and 2) some risk factors such as NBS may have time-varying effects.

Methods

This problem fits into the framework of a recently developed Bayesian dynamic Cox model for interval censored data, where each regression coefficient is allowed to be time-varying to an extent determined by the data.

Results

Application of the methodology to data from the CF Foundation Patient Registry revealed interesting findings. Compared with patients with meconium ileus or diagnosed through signs or symptoms, patients diagnosed through NBS had significantly lower risks of acquiring PPA infection between age 1 and 2 years, and the benefit in survival rate was found to last up to age 4 years. Two cohorts of five years apart were compared. Patients born in cohort 2003–2004 had significantly lower risks of the PPA infections at any age up to 4 years than those born in 1998–1999.

Conclusions

The study supports benefits of NBS on PPA infection in early childhood. In addition, our analyses demonstrate that patients in the more recent cohort had significantly lower risks of acquiring PPA infection up to age 4 years, which suggests improved CF treatment and care over time.

Electronic supplementary material

The online version of this article (doi:10.1186/s12874-016-0220-5) contains supplementary material, which is available to authorized users.

Association of meteorological and geographical factors and risk of initial Pseudomonas aeruginosa acquisition in young children with cystic fibrosis

Initial infection with the sentinel respiratory pathogen in children with cystic fibrosis (CF), Pseudomonas aeruginosa (Pa), is generally with environmental strains of this ubiquitous organism. The purpose of this study was to evaluate the associations between meteorological and geographical factors and risk of initial Pa acquisition in young children with CF. Using the U.S. Cystic Fibrosis Foundation Patient Registry from 2003 to 2009, 3463 patients met inclusion criteria, of which 48% (n = 1659) acquired Pa during follow-up. From multivariable Weibull regression, increased risk of Pa acquisition was associated with increasing temperature [hazard ratio (HR) per 1 °C: 1·13; 95% confidence interval (CI) 1·08-1·13], dew point (HR per 1 °C: 1·10, 95% CI 1·07-1·13), rainfall (HR per cm: 1·10, 95% CI 1·07-1·12), latitude (HR per 1 °C northing: 1·15, 95% CI 1·11-1·20), longitude (HR per 1 °C easting: 1·01, 95% CI 1·01-1·02) and elevation (HR per 100 m: 1·05, 95% CI 1·03-1·07). These results suggest that environmental factors may play a previously unrecognized role in the aetiology of initial Pa acquisition.

Differential geographical risk of initial Pseudomonas aeruginosa acquisition in young US children with cystic fibrosis

Pseudomonas aeruginosa is the sentinel respiratory pathogen in cystic fibrosis patients. We conducted a retrospective study to examine whether state of residence affected risk of P. aeruginosa acquisition among US children under 6 years of age with cystic fibrosis by using data from the Cystic Fibrosis Foundation National Patient Registry, 2003-2009. The outcome was time to first isolation of P. aeruginosa from a respiratory culture. We used a Bayesian hierarchical Weibull regression model with interval-censored outcomes. Spatial random effects, included at the state level and modeled using an intrinsic conditional autoregressive prior, allowed estimation of the residual spatial correlation. The regression portion of the model was adjusted for demographic and disease characteristics potentially affecting P. aeruginosa acquisition. A total of 3,608 children met the inclusion criteria and were followed for an average of 2.1 (standard deviation, 1.6) years. P. aeruginosa was cultured in 1,714 (48%) subjects. There was a moderately elevated spatial residual relative risk. An estimated 95% credible interval for the residual hazard ratio under 1 of the fitted models was 0.64-1.57; the strongest positive association was observed in the Southern states. The fact that risk for P. aeruginosa acquisition displayed spatial dependence suggests that regional factors, such as climate, may play an important role in P. aeruginosa acquisition.

Risk factors for age at initial Pseudomonas acquisition in the cystic fibrosis epic observational cohort

BACKGROUND

Risk factors for initial Pseudomonas aeruginosa (Pa) acquisition, particularly environmental exposures, are poorly understood. We aimed to identify such risk factors in order to inform prevention strategies and identify high-risk populations.

METHODS

The study cohort included all participants in the U.S. EPIC Observational Study who had no prior Pa-positive respiratory cultures (N=889). Cox proportional hazard models were used to test the effects of factors on age at first Pa-positive respiratory culture.

RESULTS

Cystic fibrosis (CF) genotype functional class had an important effect on age at initial Pa acquisition (hazard ratio (HR) comparing minimal to residual CFTR function 2.87 (95% CI 1.88, 4.39)). None of the modifiable risk factors evaluated, including cigarette smoke, hot tub use, breastfeeding, or daycare, was associated with age at Pa acquisition. Similarly, newborn screening was not associated with age at Pa acquisition (HR 0.85, 95% CI 0.66, 1.09). Key associations were validated in a CF Foundation National Patient Registry replication cohort.

CONCLUSIONS

Given the ubiquitous presence of Pa in the environment, it may be that many imposed lifestyle changes will have less impact on age at initial Pa acquisition than genetic determinants.

Long-term effects of birth order and age at diagnosis in cystic fibrosis: a sibling cohort study

BACKGROUND

Siblings with cystic fibrosis (CF) share many genetic and environmental factors but may present different phenotypes. Younger sibs are mostly earlier diagnosed with CF than their older sibs, but might be at risk for an earlier colonization with Pseudomonas aeruginosa (PA) than their older counterparts due to cross-infection within families.

AIMS

To analyze the effects of birth order and age at diagnosis on lung function, PA colonization, nutritional status, and survival during the first two decades of life in siblings with CF.

METHODS

A retrospective cohort study of 52 sibling pairs was performed in two Dutch CF centers. Data were analyzed both cross-sectionally and longitudinally using Kaplan-Meier curves and modified log-rank tests.

RESULTS

Median age at diagnosis was significantly higher in the older sib compared with the younger sib (3.0 and 0.2 years, respectively, P < 0.0001). At the age of 5, 10, and 15 years no difference in lung function was found. However, at the age of 20 years, forced expiratory volume in 1 sec (FEV(1)) in older sibs was 19.4% (95% CI: 5.9-32.9%, P = 0.007) lower than in younger sibs. In the younger sibs group, FEV(1) at age 20 years was significantly better in those who had a diagnosis before the age of 6 months (difference 22.9%, 95% CI: 0.1-45.8%, P < 0.05). In the first 10 years of life the younger sibs tended to be earlier colonized with PA than their older counterparts. No differences in nutritional status and survival were observed.

CONCLUSION

In this sibling cohort study, an early diagnosis of CF was associated with better lung function after two decades of life. Although younger siblings tended to be colonized with PA at an earlier age, they showed better lung function outcomes. This underscores the importance of early diagnosis with newborn screening and early referral to a specialized center in the prevention of long-term deleterious effects on lung function.

Lung disease at diagnosis in infants with cystic fibrosis detected by newborn screening

RATIONALE

The promise of newborn screening (NBS) for cystic fibrosis (CF) has not been fully realized, and the extent of improvement in respiratory outcomes is unclear. We hypothesized that significant lung disease was present at diagnosis.

OBJECTIVES

To determine the extent of lung disease in a geographically defined population of infants with CF diagnosed after detection by NBS.

METHODS

Fifty-seven infants (median age, 3.6 mo) with CF underwent bronchoalveolar lavage and chest computed tomography (CT) using a three-slice inspiratory and expiratory protocol.

MEASUREMENTS AND MAIN RESULTS

Despite the absence of respiratory symptoms in 48 (84.2%) of infants, a substantial proportion had lung disease with bacterial infection detected in 12 (21.1%), including Staphylococcus aureus (n = 4) and Pseudomonas aeruginosa (n = 3); neutrophilic inflammation (41. 4 x 10(3) cells/ml representing 18.7% of total cell count); proinflammatory cytokines, with 44 (77.2%) having detectable IL-8; and 17 (29.8%) having detectable free neutrophil elastase activity. Inflammation was increased in those with infection and respiratory symptoms; however, the majority of those infected were asymptomatic. Radiologic evidence of structural lung disease was common, with 46 (80.7%) having an abnormal CT; 11 (18.6%) had bronchial dilatation, 27 (45.0%) had bronchial wall thickening, and 40 (66.7%) had gas trapping. On multivariate analysis, free neutrophil elastase activity was associated with structural lung disease. Most children with structural lung disease had no clinically apparent lung disease.

CONCLUSIONS

These data support the need for full evaluation in infancy and argue for new treatment strategies, especially those targeting neutrophilic inflammation, if the promise of NBS for CF is to be realized.