ARTICLE |
a Department of Pediatrics, Alfred I. duPont Hospital for Children, Nemours Children's Clinic, Wilmington, Delaware
b Department of Pulmonary Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois
c Ovation Research Group, San Francisco, California
d Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio
e Departments of Pediatrics and Physiology, University of Arizona, Tucson, Arizona
f Department of Pediatrics, Brown University, Providence, Rhode Island
g Department of Pediatrics, University of Rochester, Rochester, New York
h Genentech, Inc, South San Francisco, California
| ABSTRACT |
|---|
|
|
|---|
METHODS. We divided cystic fibrosis sites with
20 patients who were 6 to 12 years of age into quartiles on the basis of median forced expiratory volume in 1 second of that age group in 2003 and compared demographic and clinical characteristics and treatment patterns during the first year of enrollment for patients who were aged 0 to 3 years at those sites in 1994 to 1999. The analysis included 755 infants from 12 upper quartile sites and 743 infants from 12 lower quartile sites.
RESULTS. Upper quartile sites had more infants whose disease was diagnosed by family history or newborn screening, fewer infants with symptoms at diagnosis, higher weight for age at enrollment, more white patients, and more
F508 homozygotes. Medical conditions and respiratory tract microbiology differed between sites. Infants at upper quartile sites had more office and sick visits; more respiratory tract cultures; and more frequent use of intravenous antibiotics, oral corticosteroids, mast cell stabilizers, and mucolytics; but they received less chest physiotherapy, inhaled bronchodilators, oral nutritional supplements, and pancreatic enzymes.
CONCLUSIONS. Both enrollment characteristics and infant care patterns are associated with lung function outcomes in later childhood. Our analysis suggests that pulmonary function of older children may be improved through specific interventions during the first 3 years of life.
Key Words: cystic fibrosis early practice patterns lung function outcomes
Abbreviations: CF—cystic fibrosis ESCF—Epidemiologic Study of Cystic Fibrosis FEV1—forced expiratory volume in 1 second UQ—upper quartile LQ—lower quartile
The increasing use of newborn screening1 and prenatal screening2 has led to more frequent diagnoses of cystic fibrosis (CF) in early infancy. However, there are no published guidelines for care of infants with CF, and little information is available about specific interventions that might improve eventual outcomes. Because nutritional deficits may be observed before 2 months of age, early diagnosis and treatment can prevent malnutrition and improve long-term growth.3 The nutritional benefits of newborn screening for CF also are well established.4 Although growth and nutritional indices in early life seem to correlate with lung function later in childhood,5 the pulmonary benefits of newborn screening are less clear. This may be attributable, in part, to limited knowledge of which interventions during infancy might improve long-term pulmonary outcomes.
The Epidemiologic Study of Cystic Fibrosis (ESCF and ESCF II), a multicenter, longitudinal, observational study, was initiated in 1993 to collect treatment and outcomes data on patients with CF.6 Wide variation in treatment and outcomes has been observed across sites that participated in the ESCF,6,7 and a previous analysis of this database revealed that certain patterns of care were found more often in sites with better pulmonary function outcomes.8 Because early disease care is likely to have a long-term impact on pulmonary function, we attempted to discern "best practices" for respiratory care by comparing treatment that was prescribed to infants at ESCF sites with the highest median forced expiratory volume in 1 second (FEV1) in 6- to 12-year-old children with that given at sites with the lowest FEV1.
| METHODS |
|---|
|
|
|---|
Data that were collected for each patient reflected the period from enrollment into the ESCF to 12 months after enrollment. The following demographic characteristics were collected: age, gender, race (non-Hispanic white or other), genotype, and method of CF diagnosis. Clinical characteristics included mean weight-for-age and height-for-age percentiles (during the first year of enrollment), signs and symptoms of lung disease (cough was described as none, occasional, or daily; and the presence of crackles, wheezing, and clubbing was identified using a check box), medical conditions (eg, asthma, sinusitis, elevated liver function results), microbiology and related variables, and nutritional status. The presence of asthma or sinusitis was based on the diagnostic determination of the individual physician. Practice patterns were defined by number of visits and use of parenteral antibiotics and routine therapies.
Continuous variables are presented as means ± SD, and categorical variables are presented as number (%). Two-tailed
2 tests (for categorical variables) and t tests (for continuous variables) were performed to identify any differences between UQ and LQ sites. These variables were examined further by means of multivariable logistic regression modeling, controlling for quartile, genotype, non-Hispanic race, and age. All statistical analyses and summaries were performed using SAS 9.1 (SAS Institute, Cary, NC). P < .05 was considered to be significant.
| RESULTS |
|---|
|
|
|---|
|
|
75% of clinic visits (Table 2). The incidence of clubbing was similar between groups. The difference in incidence of crackles could not be assessed because of the small number of affected patients.
|
|
|
|
|
|
| DISCUSSION |
|---|
|
|
|---|
Comparisons of site outcomes must consider the baseline characteristics of patients who attended those sites, which may not be modifiable by treatment, and differences in treatment approach. Nonmodifiable differences between UQ and LQ sites were seen in this analysis. Fewer ethnic minorities were seen at UQ sites. Minority ethnicity is associated with a lower socioeconomic status in the United States, which, in turn, is associated with poorer pulmonary function in patients with CF.9 Because socioeconomic data were not available for this analysis, it is not possible to evaluate the impact of socioeconomic status separately. Fewer pancreatic-insufficient patients, as identified by pancreatic enzyme use, were seen at UQ sites. Pancreatic insufficiency is associated with increased disease severity.10,11
Some of the risk factors that were seen at LQ sites can be modified in future populations of infants with CF. Infants from LQ sites demonstrated a greater severity of illness and a lower weight for age at enrollment. Both weight for age and severity of illness during the first year after diagnosis affect morbidity and mortality in children with CF.12,13 These risk factors can be modified by widespread implementation of newborn screening programs. Observational and randomized studies have demonstrated that early diagnosis and treatment improve long-term nutritional status and lung health12,14 and are the basis for the Centers for Disease Control and Prevention and the Cystic Fibrosis Foundation consensus for routine newborn screening for CF.15 In the United Kingdom, infants whose CF is diagnosed by newborn screening require less intensive therapies than those whose CF is diagnosed clinically.16 Our data show that ESCF sites whose 6- to 12-year-old patients have the highest pulmonary function had more infants whose CF was diagnosed by newborn screening or family history than sites with the lowest pulmonary function. These infants also seem to require less intensive therapy, because less frequent prescription of airway clearance therapy, inhaled bronchodilators, and enteral supplemental feedings were seen at UQ sites. There are no randomized, controlled studies of these therapies in CF, and the association between use of these therapies in infants and outcomes cannot be assessed adequately with the current analysis.
More patients from the LQ sites had sputum cultures positive for P aeruginosa, which is associated with greater airway inflammation and poorer lung function in ensuing years. In contrast, UQ sites performed more cultures per patient, which might be expected to allow earlier detection and treatment. Infection control practices and early intervention for P aeruginosa infection could reduce the frequency of positive P aeruginosa cultures in the population and further improve outcomes.
For achievement of the best health outcomes for infants whose CF is diagnosed without clinical symptoms and for improvement of outcomes for those whose CF is diagnosed with symptoms, it is essential to recognize and apply monitoring and treatment strategies that may improve subsequent health status. Although significant information indicates that important physiologic aberrations occur early in CF, very few data give the clinician insight into the best treatment strategies. For example, there is evidence for early airway infection and inflammation in infants and young children with CF,17,18 and structural airway abnormalities are apparent on high-resolution computed tomography scan in infants and young children with CF.19 Abnormalities that are seen on high-resolution computed tomography are prevalent even in a cohort of children with normal lung function,20 the conventional marker of lung health. Furthermore, early malnutrition has deleterious effects on cognitive function in children with CF; minimizing the duration of vitamin E deficiency may be associated with better cognitive function.21 Therefore, early diagnosis and prompt care, including close attention to growth and vitamin status, of infants with CF are expected to improve long-term outcomes. We do not know, however, which interventions might prevent bronchiectasis or slow its progression or whether specific strategies for nutrition in infants and young children could improve further later nutrition.
Although our analysis showed that sites with the highest FEV1 had a lower proportion of high-risk infants, it is important and most useful to examine the differences in treatment approaches that were used during infancy. In older children, significant differences in care patterns and outcomes have been noted at ESCF sites.7 More visits to the site, more frequent respiratory tract cultures, and more frequent use of intravenous antibiotics have been documented at UQ versus LQ sites. The present analysis shows that these specific care patterns also are seen in the care of the youngest patients at sites that later demonstrate the best pulmonary function outcomes. Despite lesser severity of illness, infants in the UQ sites were evaluated more frequently (office and sick visits), cultured more frequently, and treated more often with intravenous antibiotics (at home), oral corticosteroids, mast cell stabilizers, and mucolytics than those at LQ sites. Increased use of anti-inflammatory therapies in young children in UQ sites suggests consideration of evaluating the benefits of these agents in prospective, controlled clinical trials. Also surprising was the finding that patients at UQ sites received supplemental oxygen more frequently than those at LQ sites; given that UQ patients had a lower risk for severe lung disease, this finding might represent a variability in prescribing practices. The more frequent diagnosis of sinusitis at the UQ sites (P < .001) may be a marker for more frequent antibiotic therapy, leading to better lung function in subsequent years. The significance of this finding is difficult to determine because case report forms captured physician-diagnosed sinusitis but did not give specific criteria for this diagnosis.
It is intriguing that airway clearance and the administration of bronchodilators, interventions that the majority of CF care providers initiate early and consider to be effective, were used more frequently at the LQ than the UQ sites. It is possible that providers at UQ sites do not prescribe these therapies in asymptomatic or minimally symptomatic infants. It also is possible that UQ sites more frequently diagnose CF by newborn screening and that these patients receive less intense treatment.16 Alternatively, this finding may be explained by the variability in defining actual versus prescribed care. The case report forms were designed to capture prescribed therapy, but because case reports are extracted from the medical chart, it is possible that intended treatment, rather than actual treatment, has been captured and that parents of asymptomatic or minimally symptomatic infants are less likely to adhere to airway clearance regimens. This issue might be investigated further through a detailed survey of CF care provider practices.
It is impossible to determine fully the influence of care in previous years versus more recent or current care on pulmonary function outcomes. However, given the early onset of inflammation and bronchiectasis in CF and the progressive nature of CF lung disease, it is compelling to consider the benefits of frequent monitoring and more frequent use of antibiotics in infants and young children as strategies for improving long-term health outcomes. Our study design is limited by the use of 2 cross-sectional cohorts at identical sites rather than a true longitudinal assessment of individual patients. However, 64% of the 6- to 12-year-old patients who were used to define the outcomes cohorts were part of the infant cohort at the same care site. Nonetheless, we believe that our findings are valid. A longitudinal cohort study would be confirmatory, and multivariable analysis then would allow the ascertainment of the relative contribution of patient risk factors and treatment patterns in relation to pulmonary outcomes.
It is important to realize that an epidemiologic study can identify only associations and, as such, does not define cause and effect but rather points out opportunities for future evaluation. In the present study, observation of better lung function at ESCF sites in patients who were aged 6 to 12 years is associated with specific patient characteristics and clinical care patterns in infants in previous years. Although some patient characteristics are not modifiable, others can be modified through currently available strategies such as widespread implementation of newborn screening. Higher FEV1 is associated with specific practice patterns, including more frequent visits, more sputum cultures, and more frequent antibiotic therapy. The correlations between these practices and improved outcomes generate hypotheses for prospective research and suggest specific strategies that can be implemented in quality improvement initiatives. Frequent monitoring and use of antibiotics may preserve long-term lung health in CF.
| ACKNOWLEDGMENTS |
|---|
This study was conducted with the ESCF database.
We acknowledge the contributions of the North American Scientific Advisory Group; the investigators and study coordinators of the ESCF; and Jill Luer, PharmD, for editorial assistance.
| FOOTNOTES |
|---|
Address correspondence to Raj Padman, MD, Division of Pulmonology, Alfred I. duPont Hospital for Children, PO Box 269, Wilmington, DE 19899. E-mail: rpadman{at}nemours.org
Financial Disclosure: Drs Padman, Schechter, and Ren are consultants for Genentech, Inc; Dr McColley is a consultant and member of the speakers bureau for Genentech, Inc; Dr Miller is employed by Ovation Research Group, which receives research funding from Genentech, Inc; Dr Konstan has received research support from and is a consultant for Genentech, Inc, Novartis, Axcan-Scandipharm, and Digestive Care Inc; Dr Morgan is an advisory board member for Genentech, Inc; and Dr Wagener is an employee and shareholder of Genentech, Inc.
| REFERENCES |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
I. M Balfour-Lynn Cystic fibrosis papers of the year 2007 J R Soc Med, July 1, 2008; 101(Supplement_1): 10 - 14. [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||