Longitudinal analysis of pulmonary function decline in patients with cystic fibrosis

Murine model for cystic fibrosis bone disease demonstrates osteopenia and sex-related differences in bone formation

As the incidence of cystic fibrosis (CF) bone disease is increasing, we analyzed CF transmembrane conductance regulator (CFTR) deficient mice (CF mice) to gain pathogenic insights. In these studies comparing adult (14 wk) CF and C57BL/6J mice, both bone length and total area were decreased in CF mice. Metaphyseal trabecular and cortical density were also decreased, as well as diaphyseal cortical and total density. Trabecular bone volume was diminished in CF mice. Female CF mice revealed decreased trabecular width and number compared with C57BL/6J, whereas males demonstrated no difference in trabecular number. Female CF mice had reduced mineralizing surface and bone formation rates. Conversely, male CF mice had increased mineralizing surface, mineral apposition, and bone formation rates compared with C57BL/6J males. Bone formation rate was greater in males compared with female CF mice. Smaller bones with decreased density in CF, despite absent differences in osteoblast and osteoclast surfaces, suggest CF transmembrane conductance regulator influences bone cell activity rather than number. Differences in bone formation rate in CF mice are suggestive of inadequate bone formation in females but increased bone formation in males. This proanabolic observation in male CF mice is consistent with other clinical sex differences in CF.

Associations of psychosocial factors with health outcomes among youth with cystic fibrosis

PURPOSE

The purpose of this study was to examine the relationship of strains, resources, feelings, and behaviors about treatment adherence reported by youth with cystic fibrosis (CF) with repeated clinic measures of their pulmonary function and nutritional status.

METHODS

Linear mixed models, stratified by gender, adjusting for age, were used to examine the effects of strains, resources, and adherence behaviors on repeated pulmonary function and nutritional status measures. All 10-21 years old with CF at the Minnesota Cystic Fibrosis Center were invited by mail to participate. Of these 177 youth, 51% (43 boys, 47 girls) returned surveys. Forced expiratory volume in 1 sec and predicted weight-for-height were extracted from participants' clinic records for the 18 months following receipt of the survey.

RESULTS

Females showed significantly greater variability in repeated measures of pulmonary function and nutritional status compared to males. Parent-youth strains, physical strains, activity limitations, and cough suppression had significant effects on the 18-month mean of pulmonary function measures for females, but only physical strains had a significant effect for males.

CONCLUSION

Compared to males, females experienced more strains and poorer treatment adherence, which may be factors associated with declines in pulmonary function observed among females with CF during the adolescent years.

Improvements in lung function outcomes in children with cystic fibrosis are associated with better nutrition, fewer chronic pseudomonas aeruginosa infections, and dornase alfa use

OBJECTIVE

To compare lung function and nutritional outcomes in cystic fibrosis (CF) for 2 birth cohorts in our CF center.

STUDY DESIGN

Patients with CF born between 1985 and 2000 treated in our CF center before age 5 years were included. The patients were divided into 2 equal birth cohorts for comparison: birth cohort 1 (born between 1985 and 1992) and birth cohort 2 (born between 1993 and 2000). To compare lung function, we used forced expiratory volume in the first second (FEV(1))% predicted and FEV(1)% predicted slope from age 6 to 12 years. We hypothesized that we would find significant improvements in lung function and nutritional outcomes in our patients with CF.

RESULTS

The patients born between 1993 and 2000 (birth cohort 2) had better lung function, a slower rate of decline in lung function, and better nutritional outcomes compared with those born between 1985 and 1992 (birth cohort 1). Factors associated with a slower rate of decline in lung function in both groups were a higher baseline body mass index (BMI)%, a slower BMI% rate of decline, absence of chronic Pseudomonas aeruginosa respiratory infection, and initiation of dornase alfa (Pulmozyme) therapy before age 9 years.

CONCLUSION

Our results demonstrate dramatically improved lung function and nutritional outcomes in the children with CF in our center. The improvements in lung function outcomes are associated with better nutrition, fewer chronic P aeruginosa infections, and dornase alfa therapy.

Lung function in 3-5-year-old children with cystic fibrosis

It is well established that the lung disease of CF can occur early in life and may progress through the preschool years when accurate lung function assessment has been challenging to perform. We hypothesized that respiratory inductive plethysmography (RIP) and spirometry could be effectively performed in 3-6-year-old children and could be used to assess both longitudinal changes in lung function and the acute changes that occur during exacerbation of pulmonary disease. Both RIP and spirometry were equally feasible; however, the success rate for spirometry gradually increased with age to become higher than that for RIP in the 6-year-old subjects. Forty-four subjects were studied longitudinally and demonstrated significant increases in FVC, FEV(1), and FEV(0.5), but not in FEF(25-75) or RIP variables. There were significant differences in FVC, FEV(1), and phase angle (a measure of thoracoabdominal asynchrony) during exacerbations of lung disease. Although both RIP and spirometry were able to show differences in lung function in subjects with acute clinical worsening, spirometry was more robust in demonstrating change in lung function longitudinally and in children who had an exacerbation of lung disease.

Recurrent exacerbations affect FEV(1) decline in adult patients with cystic fibrosis

Obstructive lung disease is the major cause of morbidity and mortality in cystic fibrosis (CF). To identify risk factors contributing to FEV(1) decline in CF patients, we carried out a retrospective analysis of clinical and pulmonary function data in a population of CF patients followed up for 5 years and studied the correlation between clinical data and FEV(1) decline. Fifty-one adult CF patients were studied. The FEV(1) decline was related to the following clinical characteristics: CFTR genotype, age, gender, weight, height, age at diagnosis, baseline FEV(1), pancreatic function, presence of airway infection, pancreatic insufficiency and diabetes, number of exacerbations/year and intravenous (i.v.) antibiotic courses/year. Both the number of exacerbations/year and the number of i.v. antibiotic courses/year were strongly related to the FEV(1) decline. Patients with airway infection or with diabetes had significantly lower FEV(1) values during the study as compared with non-infected patients or patients without diabetes; however, both the presence of airway infection or diabetes did not affect the FEV(1) decline. These results suggest that the aggressive treatment of disease exacerbations is crucial for delaying lung function decline in CF.

Consensus on the use and interpretation of cystic fibrosis mutation analysis in clinical practice

It is often challenging for the clinician interested in cystic fibrosis (CF) to interpret molecular genetic results, and to integrate them in the diagnostic process. The limitations of genotyping technology, the choice of mutations to be tested, and the clinical context in which the test is administered can all influence how genetic information is interpreted. This paper describes the conclusions of a consensus conference to address the use and interpretation of CF mutation analysis in clinical settings. Although the diagnosis of CF is usually straightforward, care needs to be exercised in the use and interpretation of genetic tests: genotype information is not the final arbiter of a clinical diagnosis of CF or CF transmembrane conductance regulator (CFTR) protein related disorders. The diagnosis of these conditions is primarily based on the clinical presentation, and is supported by evaluation of CFTR function (sweat testing, nasal potential difference) and genetic analysis. None of these features are sufficient on their own to make a diagnosis of CF or CFTR-related disorders. Broad genotype/phenotype associations are useful in epidemiological studies, but CFTR genotype does not accurately predict individual outcome. The use of CFTR genotype for prediction of prognosis in people with CF at the time of their diagnosis is not recommended. The importance of communication between clinicians and medical genetic laboratories is emphasized. The results of testing and their implications should be reported in a manner understandable to the clinicians caring for CF patients.

Effectiveness of home treatment for patients with cystic fibrosis: the intravenous administration of antibiotics to treat respiratory infections

Patients with cystic fibrosis (CF) experience repeated infectious respiratory exacerbations leading to a continuous decline in lung function. The exacerbations are treated in hospital or at home. Our aim was to compare the clinical outcome for patients undergoing intravenous antibiotic treatment either in hospital or at home. A retrospective 10-year study was performed in four regional CF Centers. The outcome measures were percentage changes in forced expiratory volume in 1 sec (FEV(1)), forced vital capacity (FVC) and weight for age z-score (WZS). FEV(1), FVC, and WZS changes were calculated for the entire study period and for each course. A total of 1,164 courses were analyzed. For each course, the mean improvement in FEV(1) and FVC was significantly higher when performed in hospital than when performed at home (P < 0.05). FEV(1) and FVC values were 10.2%, 9.5% respectively in the hospital group and 7.3%, 6.8% in the home group. A total of 153 patients were analyzed (51 inpatients matched to 102 patients treated at home). The two groups had no significant differences in any outcome variable at baseline. The mean variation per year in FEV(1) was greater in the hospital group versus the home group (-0.4% vs. -1.8%; P = 0.03). The mean variation per year in WZS was greater in the hospital group versus the home group (P < 0.01). Clinical outcome, as defined by spirometric parameters and body weight, was better after a course of treatment in hospital than after a home treatment. This benefit was maintained throughout of the study period.

Valuing care recipient and family caregiver time: a comparison of methods

OBJECTIVES

The purpose of this study is to compare the approaches used for valuing family caregiver and care recipient time devoted to providing and receiving care.

METHODS

Valuation approaches were operationalized within a cohort of cystic fibrosis care recipients (n = 110). Base-case analyses, grounded in human capital theory, applied earnings estimates to caregiving time to impute the market value of time lost from labor. Unpaid labor and leisure time was valued with a replacement cost (homemaker's wage rate). Total time costs were computed and sensitivity analyses were conducted to describe the effects of alternative valuation methods on total costs.

RESULTS

The mean time cost per care recipient-caregiver dyad over 28 days was $2,026CAD. The majority (76 percent) of time costs were due to losses from unpaid labor and leisure time. Varying the valuation of paid labor time did not result in significantly different total time costs (p = .0877). However, varying the method of valuing unpaid labor and leisure time did significantly affect total costs (p < .0001).

CONCLUSIONS

Care recipients and caregivers primarily lost time from unpaid labor and leisure in the treatment of cystic fibrosis. Moreover, when the above losses were aggregated, the method of valuation greatly influenced overall results. The findings clearly indicate that omitting caregiver and unpaid labor and leisure costs may result in an inaccurate assessment of ambulatory and home-based healthcare programs.

Airway inflammation and lung function decline in childhood post-infectious bronchiolitis obliterans

Post-infectious bronchiolitis obliterans (PBO) is a rare form of chronic obstructive lung disease in children with few data on the pulmonary function outcome and underlying inflammatory process. The aim of this study was to determine the change in lung function over time and to investigate by bronchoalveolar lavage (BAL) the inflammatory characteristics of pulmonary involvement. Eleven Caucasian children with PBO were evaluated to estimate the average rate of change in lung function indices using a mixed model. The differential cytology and lymphocyte subsets of BAL fluid were analyzed. The median follow-up was 10.2 (IQR 3.2-12) years. The estimated forced expiratory volume in 1 sec (FEV1) had a baseline intercept of 57% predicted (62% predicted after bronchodilator) at 10 years of age which fell at a rate of 1.01% per year whereas the estimated forced expiratory flow 25-75 (FEF25-75) had a baseline intercept of 36% predicted (42% predicted after bronchodilator) at 10 years of age which fell at a rate of 1.04% per year. The estimated FEV1/FVC ratio had a baseline intercept of 70% (74% after bronchodilator) at 10 years of age which declined with an average slope of 1.02% per year (-1.10% per year after bronchodilator). Although the baseline and post-bronchodilator level of estimated FVC was abnormal (68% and 69% predicted, respectively) it did not change significantly with time. The median disease duration at BAL evaluation was 3.7 (IQR 0.7-8) years. The percentage differential cell counts were characterized by a significant increase in neutrophils (median 50%, IQR 1-66%), and a slight increase of lymphocytes (median 14%, IQR 7.5-15%). In conclusion, pulmonary function in childhood PBO is characterized by significant airway obstruction which deteriorates over time. The presence of an ongoing inflammatory process could explain the decline in lung function over time.

Gender differences in treatment adherence among youth with cystic fibrosis: Development of a new questionnaire

BACKGROUND

Some prior studies have reported that girls with cystic fibrosis (CF) experience higher morbidity and mortality compared to boys. In this study, the authors compared boys' and girls' perceptions of disease-related strains and resources associated with living with CF, and the relationship of these factors to CF treatment feelings and behaviors.

METHODS

All 10-21 year olds with CF at the Minnesota Cystic Fibrosis Center were invited by mail to complete a new self-report survey (Living with CF Questionnaire--LCFQ). Of these 177 youth, 58% (49 boys and 54 girls) returned surveys.

RESULTS

Exploratory and confirmatory factor analyses revealed nine factors in the LCFQ. Partial support was found for hypothesized gender differences in these factors. Compared to boys, girls reported significantly more illness-related strains and worries, including emotional strains, greater treatment discouragement, lower self-esteem, and lower adherence to some aspects of the CF treatment regimen (coughing, eating high-fat foods, taking meds/pills).

CONCLUSIONS

Living with CF appears to have a greater emotional impact on adolescent girls compared to boys. These gender differences may contribute to the poorer pulmonary function observed among girls with cystic fibrosis during the adolescent years.

Interactions between secondhand smoke and genes that affect cystic fibrosis lung disease

CONTEXT

Disease variation can be substantial even in conditions with a single gene etiology such as cystic fibrosis (CF). Simultaneously studying the effects of genes and environment may provide insight into the causes of variation.

OBJECTIVE

To determine whether secondhand smoke exposure is associated with lung function and other outcomes in individuals with CF, whether socioeconomic status affects the relationship between secondhand smoke exposure and lung disease severity, and whether specific gene-environment interactions influence the effect of secondhand smoke exposure on lung function.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective assessment of lung function, stratified by environmental and genetic factors. Data were collected by the US Cystic Fibrosis Twin and Sibling Study with missing data supplemented by the Cystic Fibrosis Foundation Data Registry. All participants were diagnosed with CF, were recruited between October 2000 and October 2006, and were primarily from the United States.

MAIN OUTCOME MEASURES

Disease-specific cross-sectional and longitudinal measures of lung function.

RESULTS

Of 812 participants with data on secondhand smoke in the home, 188 (23.2%) were exposed. Of 780 participants with data on active maternal smoking during gestation, 129 (16.5%) were exposed. Secondhand smoke exposure in the home was associated with significantly lower cross-sectional (9.8 percentile point decrease; P < .001) and longitudinal lung function (6.1 percentile point decrease; P = .007) compared with those not exposed. Regression analysis demonstrated that socioeconomic status did not confound the adverse effect of secondhand smoke exposure on lung function. Interaction between gene variants and secondhand smoke exposure resulted in significant percentile point decreases in lung function, namely in CFTR non-DeltaF508 homozygotes (12.8 percentile point decrease; P = .001), TGFbeta1-509 TT homozygotes (22.7 percentile point decrease; P = .006), and TGFbeta1 codon 10 CC homozygotes (20.3 percentile point decrease; P = .005).

CONCLUSIONS

Any exposure to secondhand smoke adversely affects both cross-sectional and longitudinal measures of lung function in individuals with CF. Variations in the gene that causes CF (CFTR) and a CF-modifier gene (TGFbeta1) amplify the negative effects of secondhand smoke exposure.

Advancing outcome measures for the new era of drug development in cystic fibrosis

The growing pipeline of candidate drugs for cystic fibrosis (CF) is challenging clinical trial research. There has been a shift from evaluating drugs aimed at treating the secondary manifestations of CF to evaluating drugs targeted toward the primary prevention of chronic lung disease. As CF is an orphan disease, there is a fundamental need to assess new therapies efficiently and accurately by mechanisms that best use the number of available patients. This need can be addressed with the continued advancement and refinement of CF outcome measures. We begin by presenting an overview of the outcome measures currently used in CF clinical studies, defined and categorized in terms of one of the three main classes of endpoints: clinical efficacy measures, surrogate endpoints, and biomarkers. To move forward efficiently, clinical research in CF is dependent on the development of new outcomes able to capture biologic and clinical response to novel therapeutic approaches. We conclude with a discussion of the criteria by which all new outcome measures should be evaluated. A systematic, rigorous approach to outcome measure development is needed to provide the tools necessary for evaluating new therapies and moving drugs out of the pipeline and into the CF clinic.

Risk factors for rate of decline in forced expiratory volume in one second in children and adolescents with cystic fibrosis

OBJECTIVES

To characterize the rate of decline of forced expiratory volume in 1 second (FEV(1)) in children and adolescents with cystic fibrosis and to identify and compare risk factors associated with FEV(1) decline.

STUDY DESIGN

The rate of decline in FEV(1)% predicted over 3 to 6 years in 3 different age groups was determined. Risk factors for decline were identified and compared among and within age groups as a function of disease severity with repeated-measures, mixed-model regression.

RESULTS

Mean (+/-SD) baseline FEV(1)% predicted was 88.4% +/- 20.5% for 6- to 8-year-olds (n = 1811), 85.3% +/- 20.8% for 9- to 12-year-olds (n = 1696), and 78.4% +/- 22.0% for 13- to 17-year-olds (n = 1359). Decline in FEV(1)% predicted/year was -1.12, -2.39, and -2.34, respectively. High baseline FEV(1) and persistent crackles were significant independent risk factors for decline across all age groups. Female sex, Pseudomonas aeruginosa infection, low weight-for-age, sputum, wheezing, sinusitis, pulmonary exacerbations treated with intravenous antibiotics, elevated liver test results, and pancreatic insufficiency were also identified as independent risk factors in some age groups.

CONCLUSIONS

This study identifies risk factors for FEV(1) decline in children and adolescents with cystic fibrosis. Clinicians should not be reassured by high lung function, particularly in young children, because this factor, among others, is independently associated with steeper decline in FEV(1).

Évolution des épreuves fonctionnelles respiratoires (EFR) chez des enfants atteints de mucoviscidose et dépistés à la naissance. Lien avec l'infection pulmonaire. Étude sur 40 enfants et 744 EFR

OBJECTIVES

To report longitudinal assessment of pulmonary function in children with neonatal screening for cystic fibrosis and its relationships with Pseudomonas aeruginosa (PA) chronic infection, nutritional status, sex, age and genotype.

POPULATION AND METHODS

Children benefited systematically of 3 visits a year with pulmonary function tests (PFT) and bacteriological examination. Forty children and 744 PFTs were analysed, with 38 children during at least 4 years.

RESULTS

We reported a decrease of pulmonary function tests with chronic PA infection and the genotype DeltaF508/DeltaF508. The decline was gradual and not different between not infected and recently infected children. The PFTs of children infected for a long times were very deteriorate, probably due to the fact that they were infected with multiresistant strains of PA.

CONCLUSION

We think that it is important to survey pulmonary function before 5 years old in these early infected children. We should determinate if the important decrease of PFT in these early infected children is due to infection by PA mucoid.

Correlation of chest radiograph pattern with genotype, age, and gender in adult cystic fibrosis: a single-center study

INTRODUCTION

Cystic fibrosis (CF) is a common lethal genetic disorder. The aim of this study was to determine the common chest radiograph (CXR) patterns in adult CF, and correlate disease distribution on CXRs with genotype, age, and gender.

METHODS

One hundred nine CF patients treated at Baylor Adult Cystic Fibrosis Center were identified. The intake CXR was reviewed and characterized as diffuse bilateral (DB), unilateral, upper lobe (UL), and lower lobe (LL) disease, or relatively normal. Lack of intake CXR, and/or genotype excluded 41 patients from analysis.

RESULTS

Of 68 patients, 38 were homozygous for DeltaF508 and 30 were heterozygous. Mean age of the population was 30 +/- 8 years (+/- SD) [range, 18 to 48 years]. The most common CXR pattern was DB; 62% had DB, 28% had UL, and 7% had LL predominance. This is in contrast to the UL-predominant CXR pattern commonly described in the pediatric population. In 18 DB patients, archived pediatric films were available, and the average patient age was 15.7 years. DB pattern was present in 16 of 18 CXRs that antedated adult intake CXRs by an average of 12.7 years. Homozygous DeltaF508 genotype was identified in 56% of patients and did not distinguish radiologic phenotypes. There was no association between radiograph pattern and identified infecting/colonizing organisms and percentage of predicted FEV(1).

CONCLUSIONS

CF has commonly been reported as an UL disease. However, in this study of adult patients, the common pattern observed was DB. A small subgroup analysis suggests that DB disease was not a pattern of disease evolution but may be present from disease onset.

Amiloride-insensitive nasal potential difference varies with the menstrual cycle in cystic fibrosis

RATIONALE

There is no adequate explanation for gender-based differences in rates of mortality and of deterioration in pulmonary function in cystic fibrosis (CF) patients. One potential explanation is that gender hormones (sex steroids) may modulate the severity of CF lung disease, the principal cause of mortality in CF, by altering respiratory transepithelial ion transport.

OBJECTIVE

To determine whether respiratory epithelial ion transport varied during the menstrual cycle of CF females.

METHODS

The nasal transepithelial electrical potential difference (NPD) was determined as a measure of ion transport across human respiratory epithelium, coincident with measurements of endogenous serum hormone levels in the luteal and follicular phases of the menstrual cycle in CF females aged 16-22 years.

RESULTS

The component of the NPD that is insensitive to the Na(+) transport blocker amiloride, but not the amiloride-sensitive component, changed in association with endogenous, menstrual cycle-induced changes in serum levels of progesterone and estrogen (P=0.02, n=7, paired t-test). Measurements using Cl(-) free perfusates suggested that the changes are not a result of Cl(-) conductance.

CONCLUSIONS

Our results suggest that in CF respiratory epithelium amiloride-insensitive, but not amiloride-sensitive, ion transport is altered by female gender hormones in vivo. We speculate that amiloride-insensitive ion transport may contribute to the regulation of human airway surface fluid.

Predictors of mortality in adults with cystic fibrosis

Assessment of prognostic indicators in patients with cystic fibrosis (CF) is important. The study's aim was to assess the relative contribution of gender, genetics and microbiology on survival in adults with CF. Adult patients were studied from 1995 to 2005 and data collected included FEV(1) (%predicted), body mass index (BMI), genetics, and microbiology. Data was available on 183 patients in 1995. Forty-five patients died in the subsequent 10 years. Patients who died during the study had lower mean (SD) FEV(1) %predicted in 1995 when compared to those remaining alive, 41.5 (15.2)% versus 69.8 (23.2)% predicted, respectively, P<0.001 and they had lower mean (SD) BMI in 1995, 19.2 (3.3) kg/m(2) in comparison to those remaining alive, 20.7 (3.4) kg/m(2), P=0.008. The proportion of patients infected with Pseudomonas aeruginosa and Burkholderia cepacia complex was higher in the group who died during the study compared to those remaining alive, odds ratio 20.9 P<0.0001 and 7.1 P<0.0001, respectively. The presence of the Delta F508 homozygous mutation did not alter survival, P=0.3. Patients infected with either P.aeruginosa or B.cepacia complex had reduced survival compared to those without infection, P=0.01 and P<0.0001, respectively. FEV(1)% (P<0.0001), infection with P.aeruginosa (P=0.005) or B.cepacia complex (P=0.03) were the only significant predictors of mortality. This study demonstrates adults who died were more likely to have worse lung function and be infected with either P.aeruginosa or B.cepacia complex. FEV(1)% and infection with P.aeruginosa or B.cepacia complex were the most significant predictors of survival in adults with CF.

Mucoviscidose : du bon usage des explorations fonctionnelles respiratoires

INTRODUCTION

Neonatal screening for cystic fibrosis (CF) leads to early dedicated specialist care for all patients.

BACKGROUND

Pulmonary function tests (PFT) are mandatory for routine monitoring of CF patients. The aim of this article is to review the current guidelines for PFTs in CF, particularly the type of test, the age and the clinical status of the patient.

VIEWPOINT

The regular use of spirometry is generally accepted. Many other tests are used but their clinical value in the routine follow-up of CF patients remains to be established.

CONCLUSION

Further efforts should be made to evaluate the value of PFTs in CF, particularly in very young children.

Heritability of lung disease severity in cystic fibrosis

RATIONALE

Obstructive lung disease, the major cause of mortality in cystic fibrosis (CF), is poorly correlated with mutations in the disease-causing gene, indicating that other factors determine severity of lung disease.

OBJECTIVES

To quantify the contribution of modifier genes to variation in CF lung disease severity.

METHODS

Pulmonary function data from patients with CF living with their affected twin or sibling were converted into reference values based on both healthy and CF populations. The best measure of FEV(1) within the last year was used for cross-sectional analysis. FEV(1) measures collected over at least 4 years were used for longitudinal analysis. Genetic contribution to disease variation (i.e., heritability) was estimated in two ways: by comparing similarity of lung function in monozygous (MZ) twins (approximately 100% gene sharing) with that of dizygous (DZ) twins/siblings (approximately 50% gene sharing), and by comparing similarity of lung function measures for related siblings to similarity for all study subjects.

MEASUREMENTS AND MAIN RESULTS

Forty-seven MZ twin pairs, 10 DZ twin pairs, and 231 sibling pairs (of a total of 526 patients) with CF were studied. Correlations for all measures of lung function for MZ twins (0.82-0.91, p < 0.0001) were higher than for DZ twins and siblings (0.50-0.64, p < 0.001). Heritability estimates from both methods were consistent for each measure of lung function and ranged from 0.54 to 1.0. Heritability estimates generally increased after adjustment for differences in nutritional status (measured as body mass index z-score).

CONCLUSIONS

Our heritability estimates indicate substantial genetic control of variation in CF lung disease severity, independent of CFTR genotype.

Spirometry in Early Childhood in Cystic Fibrosis Patients

BACKGROUND

Spirometry data in cystic fibrosis (CF) patients in early childhood is scarce, and the ability of spirometry to detect airways obstruction is debatable.

OBJECTIVE

To evaluate the ability of spirometry to detect airflow obstruction in CF patients in early childhood.

METHODS

CF children (age range, 2.5 to 6.9 years) in stable clinical condition were recruited from five CF centers. The children performed guided spirometry (SpiroGame; patented by Dr. Vilzone, 2003). Spirometry indices were compared to values of a healthy early childhood population, and were analyzed with relation to age, gender, and clinical parameters (genotype, pancreatic status, and presence of Pseudomonas in sputum or oropharyngeal cultures).

RESULTS

Seventy-six of 93 children tested performed acceptable spirometry. FVC, FEV1, forced expiratory flow in 0.5 s (FEV0.5), and forced expiratory flow at 50% of vital capacity (FEF50) were significantly lower than healthy (z scores, mean +/- SD: - 0.36 +/- 0.58, - 0.36 +/- 0.72, - 1.20 +/- 0.87; and - 1.80 +/- 1.47, respectively; p < 0.01); z scores for FEV1 and FVC were similar over the age ranges studied. However, z scores for FEV0.5 and forced expiratory flow at 25 to 75% of vital capacity were significantly lower in older children compared to younger children (p < 0.001), and a higher proportion of 6-year-old than 3-year-old children had z scores that were > 2 SDs below the mean (65% vs 5%, p < 0.03). Girls demonstrated lower FEF50 than boys (z scores: - 2.42 +/- 1.91 vs - 1.56 +/- 1.23; p < 0.001). Clinical parameters evaluated were not found to influence spirometric indices.

CONCLUSIONS

Spirometry elicited by CF patients in early childhood can serve as an important noninvasive tool for monitoring pulmonary status. FEV0.5 and flow-related volumes might be more sensitive than the traditional FEV1 in detecting and portraying changes in lung function during early childhood.

Gene modifiers of lung disease

PURPOSE OF REVIEW

Cystic fibrosis is a recessive genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, but there is great heterogeneity of lung-disease severity. If we could understand non-CFTR genetic factors (modifier genes) that contribute to the severity of lung disease, we could develop novel therapies. Early studies were small and/or phenotyping methodologies were limited; consequently, most findings have not been replicated.

RECENT FINDINGS

Several large gene-modifier studies have been established. These studies are complementary in terms of design and the types of patient, and employ specialized approaches to quantitate pulmonary disease severity. Emerging data indicate that non-CFTR genetic variants contribute to at least half the variability in pulmonary disease severity, and genetic variation in transforming growth factor beta1 clearly modifies the severity of cystic fibrosis lung disease.

SUMMARY

The cystic fibrosis community is working to identify the most important gene modifiers for lung disease. Candidate genes are currently being tested, and high-resolution, whole-genome scans are now affordable. For cystic fibrosis, several hundred thousand genetic markers (single-nucleotide polymorphisms) will identify key chromosomal regions and genes. If successful, these studies will provide the opportunity for novel approaches and therapies for cystic fibrosis lung disease.

Nutritional intake and status in children with cystic fibrosis: does age matter?

OBJECTIVES

To determine whether nutritional intake and status vary with age in children with cystic fibrosis (CF).

METHODS

Case-control study examining differences in nutritional parameters and intakes in 58 children with CF recruited from a regional centre (2000-2001) and 45 controls. Participants were divided into age groups of 5-8 years, 9-12 years and 13-16 years. Weight, height, body mass index and standard deviation scores were recorded. A 4-day food diary (51 CF, 31 controls) was calculated for macronutrients and micronutrients.

RESULTS

Energy intakes (%EAR) increased with age (112%, 115% and 116%, respectively) and were significantly higher in children with CF than controls. Lower weight and growth trends were observed in children ages 5 to 8 years (NS). Weight gain and growth was normal in children with CF ages 9 to 12 years but declined at 13 to 16 years (weight z score -0.85 vs 0.68 P = 0.003, height z score -0.54 vs 0.53 P = 0.002, body mass index z score -0.72 vs 0.41 P = 0.03). Lung function was the most significant predictor of nutritional status at 9 to 12 years (r2 = 0.37, P = 0.006) and 13 to 16 years (r2 = 0.31, P = 0.01), but was not significant in children ages 5 to 8 years.

CONCLUSION

Energy intakes increased with age in children with CF and exceeded that of healthy peers in all age groups. Weight gain and growth equaled that of healthy peers at 9 to 12 years but was suboptimal at 5 to 8 years and dramatically declines at 13 to 16 years. Energy intakes were unable to meet the clinical demands of children in these age groups. Both remain vulnerable and require greater nutritional targeting.

Variants in mannose-binding lectin and tumour necrosis factor alpha affect survival in cystic fibrosis

BACKGROUND

Patients with cystic fibrosis with the same mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene differ widely in survival suggesting other factors have a substantial role in mortality.

OBJECTIVE

To determine if the genotype distribution of variants in three putative cystic fibrosis modifier genes (tumour necrosis factor alpha (TNFalpha), transforming growth factor beta1 (TGFbeta1) or mannose-binding lectin (MBL2)) differed among patients with cystic fibrosis grouped according to age and survival status.

METHODS

Genotypes of four variants (TNFalpha-238, TNFalpha-308, TGFbeta1-509 and MBL2 O) were determined in three groups of Caucasians from a single medical centre: 101 children with cystic fibrosis (aged <17 years; mean age 9.4 years), 115 adults with cystic fibrosis (aged > or =17 years; mean age 30.8 years) and 38 non-surviving adults with cystic fibrosis (21 deceased and 17 lung transplant after 17 years of age). Genotypes of 127 healthy Caucasians in the same geographical region were used as controls. Kaplan-Meier and Cox hazard regression were used to evaluate the genotype effect on cumulative survival.

RESULTS

Genotype frequencies among adults and children with cystic fibrosis differed for TNFalpha-238 (G/G vs G/A; p = 0.022) and MBL2 (A/A vs O/O; p = 0.016). When adults with cystic fibrosis were compared to non-surviving adults with cystic fibrosis, genotype frequencies of both genes differed (TNFalpha-238G/G vs G/A; p = 0.0015 and MBL2: A/A vs O/O; p = 0.009). The hazard ratio for TNFalpha-238G/G vs G/A was 0.25 (95% CI 0.06 to 1.0, p = 0.04) and for MBL2 O/O vs A/A or A/O was 2.5 (95% CI 1.3 to 4.9, p = 0.007).

CONCLUSIONS

TNFalpha-238 G/A and MBL2 O/O genotypes appear to be genetic modifiers of survival of cystic fibrosis.

Progression of pulmonary hyperinflation and trapped gas associated with genetic and environmental factors in children with cystic fibrosis

BACKGROUND

Functional deterioration in cystic fibrosis (CF) may be reflected by increasing bronchial obstruction and, as recently shown, by ventilation inhomogeneities. This study investigated which physiological factors (airway obstruction, ventilation inhomogeneities, pulmonary hyperinflation, development of trapped gas) best express the decline in lung function, and what role specific CFTR genotypes and different types of bronchial infection may have upon this process.

METHODS

Serial annual lung function tests, performed in 152 children (77 males; 75 females) with CF (age range: 6-18 y) provided data pertaining to functional residual capacity (FRCpleth, FRCMBNW), volume of trapped gas (VTG), effective specific airway resistance (sReff), lung clearance index (LCI), and forced expiratory indices (FVC, FEV1, FEF50).

RESULTS

All lung function parameters showed progression with age. Pulmonary hyperinflation (FRCpleth > 2SDS) was already present in 39% of patients at age 6-8 yrs, increasing to 67% at age 18 yrs. The proportion of patients with VTG > 2SDS increased from 15% to 54% during this period. Children with severe pulmonary hyperinflation and trapped gas at age 6-8 yrs showed the most pronounced disease progression over time. Age related tracking of lung function parameters commences early in life, and is significantly influenced by specific CFTR genotypes. The group with chronic P. aeruginosa infection demonstrated most rapid progression in all lung function parameters, whilst those with chronic S. aureus infection had the slowest rate of progression. LCI, measured as an index of ventilation inhomogeneities was the most sensitive discriminator between the 3 types of infection examined (p < 0.0001).

CONCLUSION

The relationships between lung function indices, CFTR genotypes and infective organisms observed in this study suggest that measurement of other lung function parameters, in addition to spirometry alone, may provide important information about disease progression in CF.

Update on the application of chest computed tomography scanning to cystic fibrosis

PURPOSE OF REVIEW

To summarize the role of chest computed tomography as a tool to evaluate cystic fibrosis lung disease, and to describe what abnormalities can be detected using computed tomography and how computed tomography can be used in clinical practice.

RECENT FINDINGS

Pulmonary function tests are only an indirect measure of lung structure, and are insensitive to localized and early structural abnormalities. Computed tomography is able to detect small areas with localized severe damage. The differentiation between normal and abnormal on computed tomography is relatively easy. In half of cystic fibrosis patients, the information obtained from pulmonary function tests is discordant with the information obtained from computed tomography.

SUMMARY

Cystic fibrosis patients show lung inflammation and infection starting early in life. This leads to irreversible structural lung damage such as bronchiectasis and air trapping. Cystic fibrosis lung disease varies widely between patients. The primary aim of therapy is to prevent structural damage and to conserve lung function. Adequate monitoring of cystic fibrosis lung disease is paramount to tailor treatment to a patient's need. Computed tomography is currently the best tool to monitor lung structure, and pulmonary function tests are the best to monitor lung function.

Effect of allergic bronchopulmonary aspergillosis on lung function in children with cystic fibrosis

RATIONALE

The relationship between sensitization to Aspergillus fumigatus and progression of pulmonary function is not yet established in cystic fibrosis (CF).

OBJECTIVES

We aimed to evaluate onset of A. fumigatus sensitization and development of allergic bronchopulmonary aspergillosis (ABPA), as well as to determine the physiologic factors of lung function influencing these mechanisms in CF.

METHODS

Serial annual lung function tests performed in 122 children with CF (62 males; 60 females; age: 6-18 yr) provided data pertaining to FRC measured by plethysmography, lung clearance index, volume of trapped gas, effective specific airway resistance, and forced expiratory indices (FEV1, FEF at 50% VC). Specific IgE to recombinant A. fumigatus allergens, rAspf1 and rAspf3, served as marker for sensitization, and to rAspf4 and rAspf6 as indications for a serologic ABPA, were clinically diagnosed (Nelson criteria). By linear mixed-effect model analysis, five patient groups, (1) not sensitized and free from Pseudomonas aeruginosa, (2) intermittently P. aeruginosa colonized, (3) chronically P. aeruginosa infected, (4) sensitized, and (5) with ABPA, were retrospectively evaluated.

MEASUREMENTS AND MAIN RESULTS

A. fumigatus sensitization was best reflected by increased rAspf1+3-specific IgE levels, whereas, in most patients, sensitization was preceded by P. aeruginosa infection. Patients with ABPA demonstrated the most severe progression in all lung function parameters, and FEF at 50% VC, volume of trapped gas, and effective specific airway resistance were the best predictors (p < 0.0001). However, regarding distinction between sensitization to A. fumigatus and development of ABPA in the course of CF, chronic P. aeruginosa infection has to be taken into account.

CONCLUSIONS

Airway narrowing, gas trapping, and small airway disease are the major targets for functional derangement in ABPA.

Chest computed tomography scans should be considered as a routine investigation in cystic fibrosis

Cystic fibrosis (CF) patients demonstrate lung inflammation and infection beginning early in life. Both inflammation and infection lead to irreversible structural lung damage, primarily as bronchiectasis and fibrosis. The course of CF varies widely between patients due to genotypic and environmental differences. The primary aim of CF therapy is to prevent or delay structural damage and conserve lung function. Adequate monitoring of CF lung disease is paramount to tailoring treatment to a patient's need. Pulmonary function tests (PFTs) are important in monitoring lung function. PFTs, however, are only an indirect measure of lung structure and are insensitive to localised or early damage. By contrast, computed tomography (CT) is currently the most sensitive tool to monitor lung structure. As up to 50% of patients will have discordant staging of lung disease when PFTs are compared to CT findings, both methods are needed to adequately assess a patient's pulmonary condition and tailor the treatment strategy to the patient's needs.

Exopolysaccharides produced by clinical strains belonging to the Burkholderia cepacia complex

BACKGROUND

In the frame of a research line dedicated to better clarify the role of exopolysaccharides (EPS) in bacterial virulence, EPS produced by species of the Burkholderia cepacia complex (Bcc), namely Burkholderia multivorans, Burkholderia cenocepacia, and a Bcc member of undetermined genomovar, all isolated at the Cystic Fibrosis Regional Centre of Florence (Italy), were investigated for they structural properties.

METHODS

Three strains of B. multivorans, three of B. cenocepacia and one of a Bcc member of undetermined genomovar were isolated from CF patients. The reference strains C1576 and J2315, for genomovar II and III, respectively, were included in the study. The bacteria were grown on solid media, the exopolysaccharides produced were purified, and their structures were determined. In addition, sugar analysis of sputum samples was accomplished to search for EPS produced in vivo.

RESULTS

Six strains out of seven produced the exopolysaccharide cepacian, while one strain of B. multivorans produced a completely different polymer, previously known in the literature as PS1. Two strains synthesised very small amounts of EPS. No definitive evidence for the presence of cepacian in sputum samples was found.

CONCLUSIONS

Most strains examined produced abundant amounts of polysaccharides. Cepacian was the most common EPS isolated and its production was not associated to a particular genomovar.

Classifying severity of cystic fibrosis lung disease using longitudinal pulmonary function data

RATIONALE

The study of genetic modifiers in cystic fibrosis (CF) lung disease requires rigorous phenotyping. One type of genetic association study design compares polymorphisms in patients at extremes of phenotype, requiring accurate classification of pulmonary disease at varying ages.

OBJECTIVE

To evaluate approaches to quantify severity of pulmonary disease and their ability to discriminate between patients with CF at the extremes of phenotype.

METHODS

DeltaF508 homozygotes (n = 828) were initially classified as "severe" (approximate lowest quartile of FEV(1) (% pred) for age, 8-25 yr) or "mild" disease (highest quartile of FEV(1) for age, > or = 15 yr). FEV(1) measurements from the 5 yr before enrollment (total = 18,501 measurements; average 23 per subject) were analyzed with mixed models, and patient-specific estimates of FEV(1) (% pred) at ages 5, 10, 15, 20, and 25 yr and slope of FEV(1) versus age were examined for their ability to discriminate between groups using receiver operating characteristics (ROC) curve areas.

RESULTS

Logistic regression of severity group on mixed model (empirical Bayes) estimates of intercept and slope of FEV(1) (% pred) versus age discriminated better than did classification using FEV(1) slope alone (ROC area = 0.995 vs. 0.821) and was equivalent to using estimated FEV(1) at 20 yr of age as a single discriminator. The estimated survival percentile from a joint survival/longitudinal model provided equally good classification (ROC area = 0.994).

CONCLUSIONS

In CF, estimated FEV(1) (% pred) at 20 yr of age and the estimated survival percentile are useful indices of pulmonary disease severity.

Long term effects of azithromycin in patients with cystic fibrosis: A double blind, placebo controlled trial

BACKGROUND

Macrolides display immunomodulatory effects that may be beneficial in chronic inflammatory pulmonary diseases. The aim of the study was to document whether long term use of azithromycin may be associated with respiratory benefits in young patients with cystic fibrosis.

METHODS

A multicentre, randomised, double blind, placebo controlled trial was conducted from October 2001 to June 2003. The criteria for enrollment were age older than 6 years and forced expiratory volume in 1 second (FEV1) of 40% or more. The active group received either 250 mg or 500 mg (body weight < or > or =40 kg) of oral azithromycin three times a week for 12 months. The primary end point was change in FEV1.

RESULTS

Eighty two patients of mean (SD) age 11.0 (3.3) years and mean (SD) FEV1 85 (22)% predicted were randomised: 40 in the azithromycin group and 42 in the placebo group. Nineteen patients were infected with Pseudomonas aeruginosa. The relative change in FEV1 at month 12 did not differ significantly between the two groups. The number of pulmonary exacerbations (count ratio 0.50 (95% CI 0.32 to 0.79), p < 0.005), the time elapsed before the first pulmonary exacerbation (hazard ratio 0.37 (95% CI 0.22 to 0.63), p < 0.0001), and the number of additional courses of oral antibiotics were significantly reduced in the azithromycin group regardless of the infectious status (count ratio 0.55 (95% CI 0.36 to 0.85), p < 0.01). No severe adverse events were reported.

CONCLUSION

Long term use of low dose azithromycin in young patients with cystic fibrosis has a beneficial effect on lung disease expression, even before infection with Pseudomonas aeruginosa.

Rescue of ΔF508-CFTR trafficking and gating in human cystic fibrosis airway primary cultures by small molecules

Cystic fibrosis (CF) is a fatal genetic disease caused by mutations in cftr, a gene encoding a PKA-regulated Cl−channel. The most common mutation results in a deletion of phenylalanine at position 508 (ΔF508-CFTR) that impairs protein folding, trafficking, and channel gating in epithelial cells. In the airway, these defects alter salt and fluid transport, leading to chronic infection, inflammation, and loss of lung function. There are no drugs that specifically target mutant CFTR, and optimal treatment of CF may require repair of both the folding and gating defects. Here, we describe two classes of novel, potent small molecules identified from screening compound libraries that restore the function of ΔF508-CFTR in both recombinant cells and cultures of human bronchial epithelia isolated from CF patients. The first class partially corrects the trafficking defect by facilitating exit from the endoplasmic reticulum and restores ΔF508-CFTR-mediated Cl−transport to more than 10% of that observed in non-CF human bronchial epithelial cultures, a level expected to result in a clinical benefit in CF patients. The second class of compounds potentiates cAMP-mediated gating of ΔF508-CFTR and achieves single-channel activity similar to wild-type CFTR. The CFTR-activating effects of the two mechanisms are additive and support the rationale of a drug discovery strategy based on rescue of the basic genetic defect responsible for CF.

A method for fitting regression splines with varying polynomial order in the linear mixed model

The linear mixed model has become a widely used tool for longitudinal analysis of continuous variables. The use of regression splines in these models offers the analyst additional flexibility in the formulation of descriptive analyses, exploratory analyses and hypothesis-driven confirmatory analyses. We propose a method for fitting piecewise polynomial regression splines with varying polynomial order in the fixed effects and/or random effects of the linear mixed model. The polynomial segments are explicitly constrained by side conditions for continuity and some smoothness at the points where they join. By using a reparameterization of this explicitly constrained linear mixed model, an implicitly constrained linear mixed model is constructed that simplifies implementation of fixed-knot regression splines. The proposed approach is relatively simple, handles splines in one variable or multiple variables, and can be easily programmed using existing commercial software such as SAS or S-plus. The method is illustrated using two examples: an analysis of longitudinal viral load data from a study of subjects with acute HIV-1 infection and an analysis of 24-hour ambulatory blood pressure profiles.

Serum proteomic signature for cystic fibrosis using an antibody microarray platform

Antibody microarrays are a new proteomic technology, which we have developed as a platform for identifying a cystic fibrosis (CF)-specific serum proteomic signature. Serum samples from CF patients have been pooled and compared with equivalent pools of control sera in order to identify patterns of protein expression unique to CF. We find that the set of significantly differentially expressed proteins is enriched in protein mediators of inflammation from the NFkappaB signaling pathway, and in proteins that may be selectively expressed in CF-affected tissues such as lung and intestine. In several instances, we validate the data from the antibody microarrays by quantitative analysis with Reverse Capture Protein Microarrays. We conclude that antibody microarray technology is sensitive, quantitative, and robust, and can be useful as a proteomic platform to discriminate between sera from CF and control patients.

Association of common haplotypes of surfactant protein A1 and A2 (SFTPA1 and SFTPA2) genes with severity of lung disease in cystic fibrosis

Most individual cystic fibrosis transmembrane conductance regulator (CFTR) mutations appear not to correlate directly with severity of lung damage in cystic fibrosis (CF). Components of innate immunity, namely, mannose-binding lectin (MBL2), and surfactant protein A1 and A2 genes (SFTPA1 and SFTPA2), were shown to be critical in pulmonary host defenses. A pilot association study was conducted to identify genetic modifiers of lung disease in adult patients with CF. The structural and promoter (-221x/y) variants of MBL2, variants at codons 19, 50, 62, and 219 of SFTPA1, and at codons 9, 91, and 223 for SFTPA2, were studied in 135 adults with CF and compared to their forced expired volume in 1 sec (FEV1), diffusion of CO (DLCO), and other pulmonary scores. Predicted FEV1 was significantly lower in adults with the SFTPA1 6A3 allele and SFTPA2 1A1) allele (P = 0.01 and 0.009, respectively). The extended haplotype 6A3/1A1, which includes SFTPA1 and SFTPA2, was associated with lower pulmonary function, using FEV1 (P = 0.005) and poor pulmonary scores which were determined by American Medical Association, American Thoracic Society, and modified Shwachman-Kulczycki scores. Lower FEV1 and DLCO values were associated with MBL2 coding variants in those who had the DeltaF508 CFTR mutation (P = 0.03 and 0.004, respectively). These results support the current hypothesis that variants in pulmonary host defense molecules are potentially genetic modifiers of pulmonary disease in CF. Further work in larger populations is required to provide important new insights into the pathogenesis of CF.

Manifestations of cystic fibrosis diagnosed in adulthood

PURPOSE OF REVIEW

This review highlights the phenotypic features that lead to the diagnosis of cystic fibrosis in adults, and the prognosis of these patients.

RECENT FINDINGS

With the widespread availability of genetic testing and a greater appreciation of the clinical spectrum of the disease, the diagnosis of cystic fibrosis is being made with increasing frequency in adults. Clinical features that lead to the diagnosis include respiratory symptoms and chronic airway infection with typical cystic fibrosis pathogens such as Pseudomonas aeruginosa and Staphylococcus aureus, as well as nontuberculous mycobacteria. Often these patients have previously received diagnoses of asthma, chronic bronchitis, or emphysema. Pancreatic insufficiency is much less common in the adult receiving the diagnosis, but pancreatitis occurs with greater frequency. Occasionally, individuals receive diagnoses of apparent single-organ manifestations such as idiopathic pancreatitis or congenital bilateral absence of the vas deferens, but with negligible involvement of the respiratory tract. On rare occasions, patients receiving the diagnosis as adults can present with classic features of the disease. Although lung disease is generally less severe in cystic fibrosis patients receiving the diagnosis as adults than in adult patients who received the diagnosis as infants, the extent of bronchiectasis can nonetheless be severe. The clinical course of patients receiving a diagnosis of cystic fibrosis in adulthood is largely unknown, but frequently they have milder disease and a more favorable prognosis.

SUMMARY

Clinicians must be aware of the potential for adults with chronic respiratory tract infections, unexplained bronchiectasis, congenital bilateral absence of the vas deferens, or pancreatitis to have cystic fibrosis despite the age at presentation.

Improving rate of decline of FEV1 in young adults with cystic fibrosis

BACKGROUND

CF is characterised by a progressive decline in lung function; reductions in this decline are often used as a measure of success in clinical trials. With improvements in treatment it may be that there has been a temporal shift in the pattern of the disease.

METHODS

318 patients born in five successive cohorts and attending a specialist clinic with at least two routine measurements of lung function made between the ages of 18 and 22 were included. The declines in their lung function were estimated and compared.

RESULTS

The mean (SE) slopes for percentage predicted forced expiratory volume in 1 second (FEV(1)) and forced vital capacity (FVC) were -1.53 (0.36)% and -1.27 (0.34)%, respectively (NS). The annual deterioration in FEV(1) was -2.49%, -1.99% -2.20%, -1.65%, and -0.65% from the earliest to the most recent birth cohort; a similar pattern was observed for changes in FVC. There were no differences between male and female patients. Patients infected with Pseudomonas had a greater average decline in FEV(1) (-1.6% v -1.1%).

CONCLUSIONS

The rates of decline in lung function in young adults with CF have diminished with successive birth cohorts. This has important implications for the design of clinical studies in this disease.

Cystic fibrosis mutations and genotype-pulmonary phenotype analysis

BACKGROUND

Although there are more than 1000 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, most of them are uncommon and only limited information exists regarding genotype-pulmonary phenotype relationships.

METHODS

We determined and classified the CFTR mutations using denaturing high-performance liquid chromatography and developed new, quantitative methods to categorize pulmonary phenotypes.

RESULTS

Two novel alleles were discovered, namely G1047R and 1525-2A-->G, which were accompanied by F508del and G551D mutations, respectively. Assessment of numerous options revealed that CF pulmonary phenotype categorization in children cannot be accomplished with clinical or pulmonary function data but is facilitated by longitudinal quantitative chest radiology. It was most useful to categorize pulmonary disease status by evaluating the typical pattern of abnormalities in patients homozygous for the F508del mutation, and then compare patients with minor mutations to this typical CF pulmonary phenotype. By this method, both patients with novel mutations have pulmonary phenotypes typical of F508del homozygotes. However, patients with class IV mutations (e.g., R347P) or with pancreatic sufficiency showed serial chest radiographs that were atypically mild.

CONCLUSIONS

Longitudinal quantitative chest radiography provides a new strategy for CF pulmonary phenotype categorization that should be useful for genotype-phenotype delineation in individual patients and in both epidemiologic studies and clinical trials involving groups of children with CF.

Genetic modifiers of lung disease in cystic fibrosis

BACKGROUND

Polymorphisms in genes other than the cystic fibrosis transmembrane conductance regulator (CFTR) gene may modify the severity of pulmonary disease in patients with cystic fibrosis.

METHODS

We performed two studies with different patient samples. We first tested 808 patients who were homozygous for the DeltaF508 mutation and were classified as having either severe or mild lung disease, as defined by the lowest or highest quartile of forced expiratory volume in one second (FEV1), respectively, for age. We genotyped 16 polymorphisms in 10 genes reported by others as modifiers of disease severity in cystic fibrosis and tested for an association in patients with severe disease (263 patients) or mild disease (545). In the replication (second) study, we tested 498 patients, with various CFTR genotypes and a range of FEV1 values, for an association of the TGFbeta1 codon 10 CC genotype with low FEV1.

RESULTS

In the initial study, significant allelic and genotypic associations with phenotype were seen only for TGFbeta1 (the gene encoding transforming growth factor beta1), particularly the -509 and codon 10 polymorphisms (with P values obtained with the use of Fisher's exact test and logistic regression ranging from 0.006 to 0.0002). The odds ratio was about 2.2 for the highest-risk TGFbeta1 genotype (codon 10 CC) in association with the phenotype for severe lung disease. The replication study confirmed the association of the TGFbeta1 codon 10 CC genotype with more severe lung disease in comparisons with the use of dichotomized FEV1 for severity status (P=0.0002) and FEV1 values directly (P=0.02).

CONCLUSIONS

Genetic variation in the 5' end of TGFbeta1 or a nearby upstream region modifies disease severity in cystic fibrosis.

Dornase Alfa Reduces Air Trapping in Children With Mild Cystic Fibrosis Lung Disease

PURPOSES

To evaluate quantitative air trapping measurements in children with mild cystic fibrosis (CF) lung disease during a 1-year, double-blind, placebo-controlled, recombinant human deoxyribonuclease (rhDNase) [dornase alfa] intervention trial and compare results from quantitative air trapping with those from spirometry or visually scored high-resolution CT (HRCT) scans of the chest.

MATERIALS AND METHODS

Twenty-five children with CF randomized to either daily rhDNase or placebo aerosol were evaluated at baseline, and at 3 months and 12 months by spirometer-triggered HRCT and spirometry. Outcome variables were percentage of predicted FVC, FEV1, and forced expiratory flow, midexpiratory phase (FEF(25-75%)); total and subcomponent visual HRCT scores; and quantitative air trapping measurements derived from chest HRCT images.

RESULTS

At baseline, there were no statistical differences between groups in any of the variables used as an outcome. After 3 months of treatment, both groups had improvements in percentage of predicted FEV1 and FEF(25-75%), and total HRCT visual scores. In contrast, the rhDNase group had a 13% decrease in quantitative air trapping from baseline (severe air trapping [A3]), compared to an increase of 48% in the placebo group (p = 0.023). After 12 months, both groups had declines in percentage of predicted FVC and FEV1, but the rhDNase group retained improvements in percentage of predicted FEF(25-75%) and quantitative air trapping. The mucus plugging and total HRCT visual scores were also improved in the rhDNase group after 12 months of treatment, with and without significant differences between groups (p = 0.026 and p = 0.676). Quantitative air trapping (A3) remained improved in the rhDNase group (- 15.4%) and worsened in the placebo group (+61.3%) with nearly significant differences noted between groups (p = 0.053) after 12 months of treatment.

CONCLUSIONS

Quantitative air trapping is a more consistent sensitive outcome measure than either spirometry or total HRCT scores, and can discriminate differences in treatment effects in children with minimal CF lung disease.

Massive hemoptysis in cystic fibrosis

BACKGROUND

Massive hemoptysis is a complication commonly reported in patients with cystic fibrosis (CF). An understanding of the pathophysiology of this complication and its consequences is important for the management of patients with CF.

OBJECTIVES

To identify risk factors associated with massive hemoptysis, and to determine the prognosis of patients following an episode of massive hemoptysis.

DESIGN

A retrospective, observational cohort study of the National CF Patient Registry between the years 1990 to 1999.

PATIENTS

The Registry contained data on 28,858 patients with CF observed over 10 years at CF centers across the United States.

RESULTS

Massive hemoptysis occurred with an average annual incidence of 0.87% and in 4.1% of patients overall. There was no increased occurrence by sex, but it was more prevalent in older patients (mean age, 24.2 +/- 8.7 years [+/- SD]) with more severe pulmonary impairment (nearly 60% of patients who had an episode of massive hemoptysis had FEV1 < 40% predicted). The principal risks associated with an increased occurrence of massive hemoptysis included the presence of Staphylococcus aureus in sputum cultures (odds ratio [OR], 1.3) and diabetes (OR, 1.1). There was an increased morbidity (eg, increased hospitalizations and hospital days) and an increased 2-year mortality following massive hemoptysis.

CONCLUSION

Massive hemoptysis is a serious complication in CF patients, occurring more commonly in older patients with more advanced lung disease. Nearly 1 in 100 patients will have this complication each year. There is an attributable mortality to the complication and considerable morbidity, resulting in increased health-care utilization and a measurable decline in lung function.

Pneumothorax in cystic fibrosis

BACKGROUND

Spontaneous pneumothorax is a complication that is commonly reported in patients with cystic fibrosis (CF). An understanding of the pathophysiology of this complication and its consequences is important for the management of patients with CF.

OBJECTIVE

To identify risk factors associated with pneumothorax and to determine the prognosis of CF patients following an episode of pneumothorax.

DESIGN

A retrospective observational cohort study of the National Cystic Fibrosis Patient Registry between the years 1990 and 1999.

PATIENTS

The registry contained data on 28,858 patients with CF who had been followed up over those 10 years at CF centers across the United States.

RESULTS

Pneumothorax occurred with an average annual incidence of 0.64% and in 3.4% of patients overall. There was no increased occurrence by sex, but CF was more prevalent in older patients (mean [+/- SD] age, 21.9 +/- 9.1 years) with more severe pulmonary impairment (nearly 75% of patients with FEV1 of < 40% predicted). The principal risks associated with an increased occurrence of pneumothorax included the presence of Pseudomonas aeruginosa (odds ratio [OR], 2.3), Burkholderia cepacia (OR, 1.8), or Aspergillus (OR, 1.3) in sputum cultures, FEV1 < 30% predicted (OR, 1.5), enteral feeding (OR, 1.7), Medicaid insurance (OR, 1.1), pancreatic insufficiency (OR, 1.4), allergic bronchopulmonary aspergillosis (OR, 1.5), and massive hemoptysis (OR, 1.4). There is an increased morbidity (eg, increased number of hospitalizations and number of days spent in the hospital) and an increased 2-year mortality rate following pneumothorax.

CONCLUSION

Pneumothorax is a serious complication in CF patients, occurring more commonly in older patients with more advanced lung disease. Nearly 1 in 167 patients will experience this complication each year. There is an attributable mortality to the complication and considerable morbidity, resulting in increased health-care utilization and a measurable decline in lung function.

Gender affects self-evaluation in children with cystic fibrosis and their healthy siblings

AIM

To determine whether self-esteem among children with cystic fibrosis (CF) and their healthy siblings differs from that of a healthy reference group and whether there are differences within and between sibling pairs.

METHODS

All Swedish CF children 6-14 y old with a healthy sibling in the same age range (n=65) were invited to participate, 55 sibling pairs and their parents taking part in the study. Five aspects of the children's self-concept-physical characteristics, skills and talents, mental well-being, relations to parents and family, and relations to others-were assessed by the "I think I am" self-evaluation questionnaire. Severity of illness was assessed by means of the Shwachman Clinical Evaluation System.

RESULTS

Whereas self-evaluation did not differ between groups at a general level, healthy girls as well as those with CF scored lower than girls in the reference group on the "mental well-being" and "relations to parents and family" subscales. Comparison of gender combinations (sick girl/healthy boy, sick girl/healthy girl, sick boy/healthy boy, sick boy/healthy girl) suggested that girls pay a cost of a lesser sense of psychological well-being and feelings of inadequacy in relation to their parents and family. The Shwachman score of the sick child was not related to the level of self-esteem.

CONCLUSION

When CF is present among siblings, girls seem to carry more of the family pain than boys, a finding that calls for an increased awareness of the girls' situation by members of care teams.

Does carbon dioxide retention during exercise predict a more rapid decline in FEV1 in cystic fibrosis?

BACKGROUND

Carbon dioxide (CO2) retention during exercise is uncommon in mild to moderate lung disease in cystic fibrosis (CF). The ability to deal with increased CO2 is dependent on the degree of airflow limitation and inherent CO2 sensitivity. CO2 retention (CO2R) can be defined as a rise in P(ET)CO2 tension of > or =5 mm Hg with exercise together with a failure to reduce P(ET)CO2 tension after peak work by at least 3 mm Hg by the termination of exercise.

AIM

To ascertain if carbon dioxide retention during exercise is associated with more rapid decline in lung function.

METHODS

Annual spirometric and exercise data from 58 children aged 11-15 years, with moderate CF lung disease between 1996 and 2002 were analysed.

RESULTS

The mean FEV1 at baseline for the two groups was similar; the CO2R group (n = 15) was 62% and the non-CO2 retention group (CO2NR) was 64% (n = 43). The decline in FEV1 after 12 months was -3.2% (SD 1.1) in the CO2R group and -2.3% (SD 0.9) in the CO2NR group. The decline after 24 months was -6.3% (SD 1.3) and -1.8% (SD 1.1) respectively. After 36 months, the decline in FEV1 was -5.3% (SD 1.2) and -2.6% (SD 1.1) respectively. The overall decline in lung function was 14.8% (SD 2.1) in the CO2R group and 6.7% (SD 1.8) in the CO2NR group. Using the primary outcome measure as a decline in FEV(1) of >9%, final multivariate analysis showed that the relative risks for this model were (95% CIs in parentheses): DeltaP(ET)CO2 11.61 (3.41 to 24.12), peak VO2 1.23 (1.10 to 1.43), and initial FEV(1) 1.14 (1.02 to 1.28).

CONCLUSION

Results show that the inability to defend carbon dioxide during exercise is associated with a more rapid decline in lung function.

Palliative care in cystic fibrosis

Although advances in therapy for cystic fibrosis (CF) have dramatically increased the average life span of patients, the disease is still uniformly fatal. Little attention has been paid to methods of palliative care for patients with cystic fibrosis in the medical literature. The primary palliative care issue in end-stage CF is the management of dyspnea. An observational study done at Children's Hospital in Boston suggested that doses of morphine in the range of 5 mg per hour can control the end-stage dyspnea in CF of over 50% of patients; the rest required increasing doses with the highest dose required being 30 mg/hour. The use of mechanical ventilation at the end of life is increasing in CF, particularly for those patients awaiting lung transplantation, and it appears that the consensus against the use of aggressive care at the end of life in CF may be eroding. The use of various modes of assisted ventilation in end-stage CF will add new challenges to the compassionate provision of end-of-life care. In addition to these medical issues, palliative care in CF presents some unique psychosocial issues: there may be more than one family member with the disease, and there is an involved patient community also affected by end-of-life plans. A family-centered approach to end-of-life care for patients with CF is essential.