Birth prevalence and survival in cystic fibrosis: a national cohort study in the Netherlands

The new face of cystic fibrosis in the era of population genetic carrier screening

BACKGROUND

Population genetic carrier screening (PGCS) for cystic fibrosis (CF) has been offered to couples in Israel since 1999 and was included in a fully subsidized national program in 2008. We evaluated the impact of PGCS on CF incidence, genetic and clinical features.

METHODS

This was a retrospective national study. Demographic and clinical characteristics of children with CF born in Israel between 2008 and 2018 were obtained from the national CF registry and from patients' medical records. Data on CF births, preimplantation genetic testing (PGT), pregnancy termination and de-identified data from the PGCS program were collected.

RESULTS

CF births per 100,000 live births decreased from 8.29 in 2008 to 0.54 in 2018 (IRR = 0.84, p < 0.001). The CF pregnancy termination rate did not change (IRR = 1, p=  0.9) while the CF-related PGT rate increased markedly (IRR = 1.33, p < 0.001). One hundred and two children were born with CF between 2008 and 2018 with a median age at diagnosis of 4.8 months, range 0-111 months. Unlike the generally high uptake nationally, 65/102 had not performed PGCS. Even if all had utilized PGCS, only 51 would have been detected by the existing genetic screening panel. Clinically, 34 % of children were pancreatic sufficient compared to 23 % before 2008 (p = 0.04).

CONCLUSIONS

Since institution of a nationwide PGCS program, the birth of children with CF decreased markedly. Residual function variants and pancreatic sufficiency were more common. A broader genetic screening panel and increased PGCS utilization may further decrease the birth of children with CF.

Association of Body Mass Index With Clinical Outcomes in Patients With Cystic Fibrosis: A Systematic Review and Meta-analysis

IMPORTANCE

The prevalence of overweight (body mass index [BMI] = 25-29.9 [calculated as weight in kilograms divided by height in meters squared]) and obesity (BMI ≥30) is increasing among patients with cystic fibrosis (CF). However, it is unclear whether there is a benefit associated with increasing weight compared with the reference range (ie, normal) in CF.

OBJECTIVE

To evaluate the association of altered BMI or body composition and clinical outcomes in patients with CF.

DATA SOURCES

For this systematic review and meta-analysis, the literature search was conducted November 2, 2020, of 3 databases: MEDLINE (via PubMed), Embase, and Cochrane Central Register of Controlled Trials.

STUDY SELECTION

Patients older than 2 years diagnosed with CF with altered body composition or BMI were compared with patients having the measured parameters within the reference ranges. Records were selected by title, abstract, and full text; disagreements were resolved by consensus. Cohort studies and conference abstracts were eligible; articles with no original data and case reports were excluded.

DATA EXTRACTION AND SYNTHESIS

Two authors independently extracted data, which were validated by a third author. Studies containing insufficient poolable numerical data were included in the qualitative analysis. A random-effects model was applied in all analyses.

MAIN OUTCOMES AND MEASURES

Pulmonary function, exocrine pancreatic insufficiency (PI), and CF-related diabetes (CFRD) were investigated as primary outcomes. Odds ratios (ORs) or weighted mean differences (WMDs) with 95% CIs were calculated. The hypothesis was formulated before data collection.

RESULTS

Of 10 524 records identified, 61 met the selection criteria and were included in the qualitative analysis. Of these, 17 studies were included in the quantitative synthesis. Altogether, 9114 patients were included in the systematic review and meta-analysis. Overweight (WMD, -8.36%; 95% CI, -12.74% to -3.97%) and obesity (WMD, -12.06%; 95% CI, -23.91% to -0.22%) were associated with higher forced expiratory volume in the first second of expiration compared with normal weight. The odds for CFRD and PI were more likely in patients of normal weight (OR, 1.49; 95% CI, 1.10 to 2.00) than in those who were overweight (OR, 4.40; 95% CI, 3.00 to 6.45). High heterogeneity was shown in the analysis of pulmonary function (I2 = 46.7%-85.9%).

CONCLUSIONS AND RELEVANCE

The findings of this systematic review and meta-analysis suggest that the currently recommended target BMI in patients with CF should be reconsidered. Studies with long-term follow-up are necessary to assess the possible adverse effects of higher BMI or higher fat mass in patients with CF.

The impact of ivacaftor on sinonasal pathology in S1251N-mediated cystic fibrosis patients

IMPORTANCE

Sinonasal symptoms in patients suffering from cystic fibrosis can negatively influence the quality of life and sinuses can be a niche for pathogens causing infection and inflammation leading to a decrease of lung function. Ivacaftor, a potentiator of the Cystic Fibrosis Transmembrane Conductance Regulator protein, has shown improvement in pulmonary function in cystic fibrosis patients with different forms of class III gating mutations. However, the effects of ivacaftor on sinonasal pathology have hardly been studied.

OBJECTIVE

To determine the impact of ivacaftor therapy on sinonasal pathology in patients with cystic fibrosis with an S1251N mutation.

DESIGN

Prospective observational mono-center cohort study, between June 2015 and December 2016.

SETTING

A tertiary referral center in Utrecht, The Netherlands.

PARTICIPANTS

Eight patients with cystic fibrosis with an S1251N mutation, treated with the potentiator ivacaftor were investigated.

EXPOSURES

Ivacaftor (Kalydeco, VX-770) therapy. Computed tomography imaging of paranasal sinuses. Nasal nitric oxide concentration measurements and nasal endoscopy.

MAIN OUTCOMES AND MEASURES

Primary outcome is opacification of paranasal sinuses examined with computed tomography scan analysis and scaled by the modified Lund-Mackay score before and one year after treatment. Secondary outcomes are nasal nitric oxide concentration levels, sinonasal symptoms and nasal endoscopic findings before and approximately two months and in some cases one year after treatment.

RESULTS

Computed tomography scan analysis showed a significant decrease in opacification of the majority of paranasal sinuses comparing the opacification score per paranasal sinus before and after one year of treatment with ivacaftor. Median nasal nitric oxide levels significantly improved from 220.00 (IQR:136.00-341.18) to 462.84 (IQR:233.17-636.25) (p = 0.017) parts per billion. Likewise, the majority of sinonasal symptoms and nasal endoscopic pathology decreased or resolved at two months after the use of ivacaftor.

CONCLUSION AND RELEVANCE

Ivacaftor appears to improve sinonasal outcome parameters and thereby sinonasal health in patients with cystic fibrosis with an S1251N mutation.

Rapid early increase in BMI is associated with impaired longitudinal growth in children with cystic fibrosis

BACKGROUND

We aimed to assess whether final height in children with cystic fibrosis (CF) is affected by body mass index (BMI), BMI increase, pulmonary function, and cystic fibrosis-related diabetes (CFRD).

STUDY DESIGN

A longitudinal, retrospective study was performed in a cohort of 57 patients with CF (30 boys, 27 girls) born between 1997 and 2001. Height and weight were recorded annually from ages 0.5 to 10 years and biannually up to the age of 18. Measurements were converted to height-for-age-adjusted-for-target-height (HFA-TH) and BMI-for-age z-scores. Analyses were performed using the independent t tests and the Pearson's correlation.

RESULTS

For both boys and girls, HFA-TH and BMI-for-age z-scores were significantly lower in the first year of life, these scores increased rapidly until the age of 11 and 8 years, respectively. In boys, HFA-TH z-scores declined during puberty, with subsequently significantly impaired final height (z-score, -0.56, n = 30, standard deviation [SD] = 0.81, P = 0.001). In girls, HFA-TH z-scores briefly declined after the age of 8 years, but then increased to a z-score of -0.21 (n = 27, SD = 0.87) at age 18, which is not significantly lower than the national average (P = 0.22). Pulmonary function and the presence of CFRD were not associated with final height. However, rapid BMI increase between ages 1 and 6 was negatively associated with final height in boys (n = 29, r =-0.420; P = 0.023) and girls (n = 25, r =-0.466; P = 0.019).

CONCLUSIONS

In boys and girls, early BMI increase was associated with impaired final height. We suggest that early childhood serves as a "window" in which nutritional variations may program subsequent growth. Further refinement of nutritional strategies could be needed.

Vitamin D intake, serum 25-hydroxy vitamin D and pulmonary function in paediatric patients with cystic fibrosis: a longitudinal approach

Pancreatic-insufficient children with cystic fibrosis (CF) receive age-group-specific vitamin D supplementation according to international CF nutritional guidelines. The potential advantageous immunomodulatory effect of serum 25-hydroxy vitamin D (25(OH)D) on pulmonary function (PF) is yet to be established and is complicated by CF-related vitamin D malabsorption. We aimed to assess whether current recommendations are optimal for preventing deficiencies and whether higher serum 25(OH)D levels have long-term beneficial effects on PF. We examined the longitudinal relationship between vitamin D intake, serum 25(OH)D and PF in 190 CF children during a 4-year follow-up period. We found a significant relationship between total vitamin D intake and serum 25(OH)D (β = 0·02; 95 % CI 0·01, 0·03; P = 0·000). However, serum 25(OH)D decreased with increasing body weight (β = –0·79; 95 % CI –1·28, –0·29; P = 0·002). Furthermore, we observed a significant relationship between serum 25(OH)D and forced expiratory volume in 1 s (β = 0·056; 95 % CI 0·01, 0·102; P = 0·018) and forced vital capacity (β = 0·045; 95 % CI 0·008, 0·082; P = 0·017). In the present large study sample, vitamin D intake is associated with serum 25(OH)D levels, and adequate serum 25(OH)D levels may contribute to the preservation of PF in children with CF. Furthermore, to maintain adequate levels of serum 25(OH)D, vitamin D supplementation should increase with increasing body weight. Adjustments of the international CF nutritional guidelines, in which vitamin D supplementation increases with increasing weight, should be considered.

Disease Heritability Inferred from Familial Relationships Reported in Medical Records

Heritability is essential for understanding the biological causes of disease but requires laborious patient recruitment and phenotype ascertainment. Electronic health records (EHRs) passively capture a wide range of clinically relevant data and provide a resource for studying the heritability of traits that are not typically accessible. EHRs contain next-of-kin information collected via patient emergency contact forms, but until now, these data have gone unused in research. We mined emergency contact data at three academic medical centers and identified 7.4 million familial relationships while maintaining patient privacy. Identified relationships were consistent with genetically derived relatedness. We used EHR data to compute heritability estimates for 500 disease phenotypes. Overall, estimates were consistent with the literature and between sites. Inconsistencies were indicative of limitations and opportunities unique to EHR research. These analyses provide a validation of the use of EHRs for genetics and disease research.

The relationship between energy intake and body-growth in children with cystic fibrosis

BACKGROUND & AIMS

Body-growth, expressed as weight- and height gain, is a strong predictor of morbidity and mortality in patients with cystic fibrosis (CF). Whether current historically based recommendations on a high-energy diet are sufficient for optimal growth is questionable. We therefore assessed the longitudinal relation between body-growth and routine energy intake in paediatric CF patients.

METHODS

Included were patients with CF, aged 2-10 years of whom we obtained 969 measurements of weight and height along with dietary records, and 786 coefficient of fat absorption measurements (CFA). We described body-growth, energy intake, macronutrient intake and the long-term effect of energy intake and coefficient of fat absorption on body-growth during the 8-year follow-up period.

RESULTS

Enrolled were 191 children with CF who had a compromised growth when compared to healthy children. The dietary intake was ≥110% estimated average requirement (EAR) in 47% of the measurements (457/969) and did not (fully) achieve the recommended high-energy level (110-200% EAR). Further, the intake expressed as EAR decreased with increasing age. Cross-sectionally, boys and girls with higher caloric intakes had higher weight-for-age (WFA). The caloric intake explained 18 and 6% of the variation. Further, boys with higher caloric intakes had also higher height-for-age-adjusted-for-target-height (HFA/TH) or BMI. The caloric intake explained 6 or 7% of the variation. Longitudinally, caloric intake was associated with both WFA in boys and girls, and with BMI in boys. Each 100 calories increased intake would result in a 0.01 (girls)-0.02 increase in z-score WFA and 0.03 increase in z-score BMI. We found no significant association between CFA and WFA, HFA/TH or BMI. The contribution of protein, fat and carbohydrates was not associated with WFA, nor with HFA/TH or BMI.

CONCLUSION

Even at this relatively early age, a compromised growth in children with CF was found when compared to healthy children. The energy intake was below 110% EAR in 47% of the measurements, and appeared to be insufficient to prevent suboptimal body-growth over the 8-years of follow-up.

Exercise performance and quality of life in children with cystic fibrosis and mildly impaired lung function: relation with antibiotic treatments and hospitalization

This study evaluates the impact of antibiotic treatments and hospitalization on exercise performance and health-related quality of life (QOL) in children with mild cystic fibrosis (CF) lung disease. Forty-seven children between 7 and 17 years with mild CF underwent a maximal exercise test including spiro-ergometry and filled out a QOL-questionnaire (PedsQL™). Amount of antibiotic treatments (AB) and hospitalization days in the last 3 years were reviewed. FEV1% was mildly decreased (91.7 ± 17.9 L/min, p = 0.02). Maximal oxygen consumption (VO₂max), test duration and anaerobic threshold were lower compared to a control population (VO₂max% 94 ± 15 vs 103 ± 13, p = 0.009). FEV1% correlated with AB and hospitalization episodes in the last year and 3 years before testing, VO₂max% only correlated with AB in the last 3 years. Domains of school functioning and emotional functioning were low. Children with higher VO₂max% and less AB in the last 3 years had better physical health. Physical health and school functioning were negatively correlated with hospitalization days in the last year.

CONCLUSION

Patients with mild CF lung disease have good exercise performance although still lower than the normal population. VO2max% is affected by number of antibiotic treatments over a longer period. There is an impact of hospitalization days on quality of life. What is Known: • Children with CF have lower exercise performance; there is an association between hospitalization frequency and exercise performance • Quality of life is diminished in children with CF and influenced by respiratory infections What is New: • Even patients with mild CF lung disease have lower maximal exercise performance (VO ₂ max) and a lower anaerobic threshold; VO ₂ max is lower in children who had more antibiotic treatments in the last 3 years • School and emotional functioning are diminished in children with mild CF lung disease; hospitalization is negatively correlated with school functioning and physical functioning.

Dietary intake and lipid profile in children and adolescents with cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) patients are advised to derive 35% of their daily energy intake from dietary fat. Whether this high fat intake is associated with dyslipidaemia is unknown. We described the lipid profile and dietary intake in paediatric patients with CF.

METHODS

110 fasting lipid concentrations of 110 Dutch patients with CF were studied, along with 86 measurements of dietary intake. For the total group and for boys and girls separately, the lipid profile and the dietary intake were investigated. The cross-sectional relationship between the lipid concentrations and dietary intake was determined.

RESULTS

The mean dietary fat intake was ≥35% of the total energy intake, along with a considerable consumption of saturated fat. We found lower concentrations of cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol, and increased concentrations of triglyceride and triglyceride to high-density lipoprotein cholesterol ratios. Lipid concentrations were not associated with dietary fat intake.

CONCLUSION

This study lacks variation in dietary fat intake to exclude an effect on lipid concentrations as the distribution of dietary fat intake remained constant at a high level. Elevated triglyceride concentrations and triglyceride to high-density lipoprotein cholesterol ratios suggest an increased risk of cardiovascular disease. Any negative consequences of a high dietary fat intake on the overall lipid profile later in life cannot be excluded.

Assessing Differences in Mortality Rates and Risk Factors Between Hispanic and Non-Hispanic Patients With Cystic Fibrosis in California

BACKGROUND

Over the past 30 years, therapeutic advances have extended the median lifespan of patients with cystic fibrosis (CF). Hispanic patients are a vulnerable subpopulation with a high prevalence of risk factors for worse health outcomes. The consequences of these differences on health outcomes have not been well described. The objective of this study was to characterize the difference in health outcomes, including mortality rate, between Hispanic and non-Hispanic patients with CF.

METHODS

This study is a retrospective analysis of CF Foundation Patient Registry data of California residents with CF, diagnosed during or after 1991, from 1991 to 2010. Ethnicity was self-reported. The primary outcome was mortality. Hazard ratios were estimated from a Cox regression model, stratified by sex, and adjusted for socioeconomic status, clinical risk factors, and year of diagnosis.

RESULTS

Of 1,719 patients, 485 (28.2%) self-identified as Hispanic. Eighty-five deaths occurred, with an overall mortality rate of 4.9%. The unadjusted mortality rate was higher among Hispanic patients than among non-Hispanic patients (9.1% vs 3.3%, P < .0001). Compared with non-Hispanic patients, Hispanic patients had a lower survival rate 18 years after diagnosis (75.9% vs 91.5%, P < .0001). Adjusted for socioeconomic status and clinical risk factors, Hispanic patients had an increased rate of death compared with non-Hispanic patients (hazard ratio, 2.81; 95% CI, 1.70-4.63).

CONCLUSIONS

Hispanic patients with CF have a higher mortality rate than do non-Hispanic patients, even after adjusting for socioeconomic status and clinical severity. Further investigation into the mechanism for the measured difference in lung function will help inform interventions and improve the health of all patients with CF.

Showing Value in Newborn Screening: Challenges in Quantifying the Effectiveness and Cost-Effectiveness of Early Detection of Phenylketonuria and Cystic Fibrosis

Decision makers sometimes request information on the cost savings, cost-effectiveness, or cost-benefit of public health programs. In practice, quantifying the health and economic benefits of population-level screening programs such as newborn screening (NBS) is challenging. It requires that one specify the frequencies of health outcomes and events, such as hospitalizations, for a cohort of children with a given condition under two different scenarios-with or without NBS. Such analyses also assume that everything else, including treatments, is the same between groups. Lack of comparable data for representative screened and unscreened cohorts that are exposed to the same treatments following diagnosis can result in either under- or over-statement of differences. Accordingly, the benefits of early detection may be understated or overstated. This paper illustrates these common problems through a review of past economic evaluations of screening for two historically significant conditions, phenylketonuria and cystic fibrosis. In both examples qualitative judgments about the value of prompt identification and early treatment to an affected child were more influential than specific numerical estimates of lives or costs saved.

Clinical evaluation of the Nanoduct sweat test system in the diagnosis of cystic fibrosis after newborn screening

After a positive newborn screening test for cystic fibrosis (CF), a sweat test is performed to confirm the diagnosis. The success rate of the generally acknowledged methods (Macroduct/Gibson and Cooke) in newborns varies between 73 and 99%. The Nanoduct sweat test system is easier to perform and less sweat is needed. The main aim of this study was to measure the success rate of the Nanoduct compared to current approved sweat test methods in a newborn population. After informed consent of the parents, newborns with a positive screening test for CF were included. The Macroduct or Gibson and Cooke and Nanoduct were performed in all infants, during the same appointment. The chloride concentration was determined by standard coulorimetry; conductivity was measured directly and converted to a NaCl molarity. One hundred eight newborns were included: 17 with CF, 7 with cystic fibrosis transmembrane regulator (CFTR)-related metabolic syndrome (CRMS), and 84 healthy children. The success rate of the Nanoduct was 93% and for the Macroduct/Gibson and Cooke 79% (McNemar, p = 0.002). The Nanoduct detected the same CF patients as the Macroduct/Gibson and Cooke; one CF patient had an equivocal result for both tests, and no patients were missed. The area under the receiver operating characteristic curve for detection of CF with the Nanoduct was 0.999, with ideal cutoff levels of 91 and 66 mmol/l, comparable to former studies.

CONCLUSION

The success rate of the Nanoduct to collect sufficient sweat in infants was higher compared to the Macroduct and Gibson and Cooke.

Allele frequency for Cystic fibrosis in Indians vis-a/-vis global populations

Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene. This gene encodes a protein involved in epithelial anion channel. Cystic fibrosis is the most common life-limiting genetic disorder in Caucasians; it also affects other ethnic groups like the Blacks and the Native Americans. Cystic fibrosis is considered to be rare among individuals from the Indian subcontinent. We analyzed a total of 29 world׳s populations for cystic fibrosis on the basis of gene frequency and heterozygosity. Among 29 countries Switzerland revealed the highest gene frequency and heterozygosity for CF (0.022, 0.043) whereas Japan recorded the lowest values (0.002, 0.004) followed by India (0.004, 0.008). Our analysis suggests that the prevalence of cystic fibrosis is very low in India.

Overweight and obesity in patients with cystic fibrosis: a center-based analysis

OBJECTIVE

Cystic fibrosis (CF) has long been associated with malnutrition. However, due to early diagnosis, nutritional supplements, and increased prevalence of obesity in the general population, overweight, and obesity in the CF patient population is becoming a concern. The aim of this study was to determine the prevalence of obesity and overweight in patients with CF seen at our center, to analyze factors associated with nutritional status, to evaluate the relation between nutritional status and lung function, and to document any adverse health outcomes.

METHODS

The CF Patient Registry was queried for patients aged 2-18 who were seen at our center between June 2011 and June 2012. Nutritional statuses of patients were classified in accordance with the CF Foundation guidelines. Analysis of variance was utilized to analyze the differences in lung function between the five weight status groups.

RESULTS

Of the 226 patients with CF aged 2-18 years, 129 (57%) had a BMI percentile consistent with a healthy weight status, 16 (7%) were in nutritional failure, 28 (12%) were at risk of nutritional failure, 35 (15%) were overweight, and 18 (8%) were obese. Based on fecal elastase levels, 50% of the overweight patients and 20% of the obese patients were pancreatic insufficient. FEV1 % predicted was lowest in patients with nutritional failure (P = 0.005). No significant differences were noted between the other four weight groups. In our obese and overweight population, three patients have impaired glucose tolerance, one has CF-related diabetes (CFRD) with fasting hyperglycemia, three have hypertension, and one has obstructive sleep apnea (OSA).

CONCLUSIONS

The prevalence of overweight and obesity in our CF center is noteworthy, and a significant number of the patients were pancreatic insufficient. In our patient population, overweight, and obesity were not associated with further improvement of lung function. Nutritional approaches need to address the adverse outcomes of overweight and obesity.

A contemporary survival analysis of individuals with cystic fibrosis: a cohort study

Previously established predictors of survival may no longer apply in the current era of cystic fibrosis (CF) care. Our objective was to identify risk factors associated with survival in a contemporary CF population.

We used the Canadian CF Registry, a population-based cohort, to calculate median age of survival and summarise patient characteristics from 1990 to 2012. Clinical, demographic and geographical factors, and survival were estimated for a contemporary cohort (2000–2012) using Cox proportional hazards models.

There were 5787 individuals in the registry between 1990 and 2012. Median survival age increased from 31.9 years (95% CI 28.3–35.2 years) in 1990 to 49.7 years (95% CI 46.1–52.2 years) in the most current 5-year window ending in 2012. Median forced expiratory volume in 1 s improved (p=0.04) and fewer subjects were malnourished (p<0.001) over time. Malnourished patients (hazard ratio (HR) 2.1, 95% CI 1.6–2.8), those with multiple exacerbations (HR 4.5, 95% CI 3.2–6.4) and women with CF-related diabetes (HR 1.8, 95% CI 1.2–2.7) were at increased risk of death.

Life expectancy in Canadians with CF is increasing. Modifiable risk factors such as malnutrition and pulmonary exacerbations are associated with an increased risk of death. The sex gap in CF survival may be explained by an increased hazard for death in women with CF-related diabetes.

Cost-effectiveness of newborn screening for cystic fibrosis determined with real-life data

BACKGROUND

Previous cost-effectiveness studies using data from the literature showed that newborn screening for cystic fibrosis (NBSCF) is a good economic option with positive health effects and longer survival.

METHODS

We used primary data to compare cost-effectiveness of four screening strategies for NBSCF, i.e. immunoreactive trypsinogen-testing followed by pancreatitis-associated protein-testing (IRT-PAP), IRT-DNA, IRT-DNA-sequencing, and IRT-PAP-DNA-sequencing, each compared to no-screening. A previously developed decision analysis model for NBSCF was fed with model parameters mainly based on a study evaluating two novel screening strategies among 145,499 newborns in The Netherlands.

RESULTS

The four screening strategies had cost-effectiveness ratios varying from €23,600 to €29,200 per life-year gained. IRT-PAP had the most favourable cost-effectiveness ratio. Additional life-years can be gained by IRT-DNA but against higher costs. When treatment costs reduce with 5% due to early diagnosis, screening will lead to financial savings.

CONCLUSION

NBSCF is as an economically justifiable public health initiative. Of the four strategies tested IRT-PAP is the most economic and this finding should be included in any decision making model, when considering implementation of newborn screening for CF.

Differences in clinical condition and genotype at time of diagnosis of cystic fibrosis by newborn screening or by symptoms

BACKGROUND

Early diagnosis through newborn screening (NBS) and early treatment of cystic fibrosis (CF) do lead to better prognosis. In the Netherlands, the median age for a clinical diagnosis is six months, and after newborn screening this is 30 days. It is unknown if being diagnosed at the age of six months or before two months leads to a clinically relevant difference of the clinical condition at the time of diagnosis.

AIM

The aim of this study is to assess the differences in clinical parameters at diagnosis between children with CF identified by newborn screening (NBS) or by clinical diagnosis (CD) in the Netherlands.

METHODS

From July 1st, 2007 to January 1st, 2012 all newly diagnosed CF patients were reported to the Dutch Paediatric Surveillance Unit (DPSU). All paediatricians received a questionnaire to collect data on mutations and clinical condition at diagnosis. Non-classical CF was excluded from the analysis on clinical condition.

RESULTS

204 new CF diagnoses were reported to the DPSU, 33 were reported twice and three had no CF after further testing. 127 questionnaires were returned (76%); 85 children were diagnosed because of clinical symptoms, 40 after NBS and two because of a positive family history. The median age at diagnosis was 34 weeks for a clinical diagnosis and 3 weeks after NBS. Non-classical CF was more prevalent in the NBS group (6 clinical, 14 NBS), mostly F508del/R117H7T (12). Compared to the NBS group, significantly more patients in the CD group showed failure to thrive, respiratory symptoms, and hospitalizations. 62% of the CD group showed abnormal signs at physical examination compared to 4% of the NBS group.

CONCLUSION

At the time of diagnosis infants detected after NBS are in a significantly better condition than after a clinical diagnosis. Growth retardation is already seen when after NBS the diagnosis is confirmed, but NBS leads to a diagnosis before respiratory symptoms have developed.

Rate of improvement of CF life expectancy exceeds that of general population--observational death registration study

BACKGROUND

It is unclear why cystic fibrosis (CF) survival has improved. We wished to quantify increases in CF median age of death in the context of general population survival improvement.

METHOD

Death registration data analysis (US, England & Wales (E&W)-1972-2009).

RESULTS

CF median age of death is higher in US than E&W and greater for males, opposite to that of death from all causes. CF median age of death has increased by 0.543 life years per year (E&W, US combined (95% confidence interval 0.506, 0.582)). The difference in median age at death between those dying from all causes and CF decreased in both territories. CF median age of death for males is greater than for females in both territories. This gap has not narrowed.

CONCLUSION

The median age of death of people with CF is improving more rapidly than that of the general population in US and E&W.

Estimating peak oxygen uptake in adolescents with cystic fibrosis

OBJECTIVES

To predict peak oxygen uptake (VO2 peak) from the peak work rate (W peak) obtained during a cycle ergometry test using the Godfrey protocol in adolescents with cystic fibrosis (CF), and assess the accuracy of the model for prognostication clustering.

METHODS

Out of our database of anthropometric, spirometric and maximal exercise data from adolescents with CF (N=363; 140 girls and 223 boys; age 14.77 ± 1.73 years; mean expiratory volume in 1 s (FEV1%pred) 86.82 ± 17.77%), a regression equation was developed to predict VO2 peak (mL/min). Afterwards, this prediction model was validated with cardiopulmonary exercise data from another 60 adolescents with CF (28 girls, 32 boys; mean age 14.6 ± 1.67 years; mean FEV1%pred 85.43 ± 20.01%).

RESULTS

We developed a regression model VO2 peak (mL/min)=216.3-138.7 × sex (0=male; 1=female)+11.5 × W peak; R(2)=0.91; SE of the estimate (SEE) 172.57. A statistically significant difference (107 mL/min; p<0.001) was found between predicted VO2 peak and measured VO2 peak in the validation group. However, this difference was not clinically relevant because the difference was within the SEE of the model. Furthermore, we found high positive predictive and negative predictive values for the model for prognostication clustering (PPV 50-87% vs NPV 82-94%).

CONCLUSIONS

In the absence of direct VO2 peak assessment it is possible to estimate VO2 peak in adolescents with CF using only a cycle ergometer. Furthermore, the regression model showed to be able to discriminate patients in different prognosis clusters based on exercise capacity.

Distal intestinal obstruction syndrome in cystic fibrosis: presentation, outcome and management in a tertiary hospital (2007-2012)

BACKGROUND

Cystic fibrosis (CF) can result in distal intestinal obstruction syndrome (DIOS) due to inspissated mucus. This paper describes the clinicopathological characteristics of adult CF patients with DIOS and assesses risk factors for surgery.

METHODS

A retrospective audit of CF patients at the Alfred Hospital from January 2007 to February 2012 was carried out. Patients who had 'bowel obstruction or constipation' were abstracted from the database, and medical records were reviewed for a diagnosis of DIOS.

RESULTS

Forty-five encounters of 35 patients were extracted. Twenty-five (83%) patients were homozygous for the delta F508 mutations, 29 (85%) had pancreatic insufficiency and 15 (44%) had a lung transplant. Patients presented with abdominal pain (96% of encounters), nausea (76% of encounters) and vomiting (67% of encounters). Computed tomography (CT) was performed in 20 episodes. Compared with CT, abdominal X-ray had a sensitivity of 63% (95% confidence interval (CI) 30-89%) and specificity of 33% (95% CI 8-70%) for detecting DIOS with obstruction. Forty-one (91%) encounters resolved with medical management within 2-3 days. Three patients required surgical intervention in four episodes. Previous laparotomy (odds ratio (OR) 28.5, 95% CI 1.3-624, P=0.03) and history of meconium ileus (OR 14, 95% CI 1-192, P<0.05) were statistically significant predictors of progression to surgical management.

CONCLUSION

In most patients with DIOS, the obstruction resolves with medical management. Early consultation with a CF service, assessment for a surgical abdomen and involvement of surgeons where appropriate is recommended. A history of previous laparotomy is a risk factor for the need for surgical intervention.

Evidence for decline in the incidence of cystic fibrosis: a 35-year observational study in Brittany, France

BACKGROUND

Cystic fibrosis (CF) is an autosomal recessive disorder whose incidence has long been estimated as 1/2500 live births in Caucasians. Expanding implementation of newborn screening (NBS) programs now allows a better monitoring of the disease incidence, what is essential to make reliable predictions for disease management. This study assessed time trends in the birth incidence of CF over a long period (35 years: 1975-2009) in an area where CF is frequent (Brittany, France) and where NBS has been implemented for more than 20 years.

METHODS

This study enrolled CF patients born in Brittany between January 1st 1975 and December 31st 2009 (n = 483). Time trends in incidence were examined using Poisson regression and mainly expressed using the average percent change (APC).

RESULTS

The average number of patients born each year declined from 18.6 in the late 1970's (period 1975-79) to 11.6 nowadays (period 2005-09). The corresponding incidence rates dropped from 1/1983 to 1/3268, which represented a decline close to 40% between these two periods (APC = -39.3%, 95% CI = -55.8% to -16.7%, p = 0.0020). A clear breakpoint in incidence rate was observed at the end of the 1980's (p < 0.0001). However, the incidence rate has remained quite stable since that time (annual APC = -1.0%, 95% CI = -3.0% to 1.1%, p = 0.3516).

CONCLUSIONS

This study provides an accurate picture of the evolution of the incidence of a genetic disease over a long period and highlights how it is influenced by the health policies implemented. We observed a 40% drop in incidence in our area which seems consecutive to the availability of prenatal diagnosis.

How about your peers? Cystic fibrosis questionnaire data from healthy children and adolescents

Background

The Cystic Fibrosis Questionnaire (CFQ) is widely used in research as an instrument to measure quality of life in patients with cystic fibrosis (CF). In routine patient care however, measuring quality of life is still not implemented in guidelines. One of the reasons might be the lack of consensus on how to interpret CFQ scores of an individual patient, because appropriate reference data are lacking. The question which scores reflect normal functioning and which scores reflect clinically relevant problems is still unanswered. Moreover, there is no knowledge about how healthy children and adolescents report on their quality of life (on the CFQ). With regard to quality of life the effect of normal development should be taken into account, especially in childhood and adolescence. Therefore, it is important to gain more knowledge about how healthy children and adolescents report on their quality of life and if there are any difference in a healthy populations based on age or gender. Without these data we cannot adequately interpret the CFQ as a tool in clinical care to provide patient-tailored care. Therefore this study collected data of the CFQ in healthy children and adolescents with the aim to refer health status of CF youngsters to that of healthy peers.

Methods

The CFQ was completed by 478 healthy Dutch children and adolescents (aged 6-20) in a cross-sectional study.

Results

The majority of healthy children (over 65%) did not reach maximum scores on most domains of the CFQ. Median CFQ-scores of healthy children and adolescents ranged from 67 to 100 (on a scale of 0-100) on the different CFQ-domains. Significant differences in quality of life exist among healthy children and adolescents, and these depend on age and gender.

Conclusions

Reference data of quality of life scores from a healthy population are essential for adequate interpretation of quality of life in young patients with CF. Clinicians should be aware that the perception of health-related quality of life is not as disease-specific as one might think and also relies on factors such as age, normal maturation and gender.

Intestinal obstruction syndromes in cystic fibrosis: meconium ileus, distal intestinal obstruction syndrome, and constipation

Meconium ileus at birth, distal intestinal obstruction syndrome (DIOS), and constipation are an interrelated group of intestinal obstruction syndromes with a variable severity of obstruction that occurs in cystic fibrosis patients. Long-term follow-up studies show that today meconium ileus is not a risk factor for impaired nutritional status, pulmonary function, or survival. DIOS and constipation are frequently seen in cystic fibrosis patients, especially later in life; genetic, dietary, and other associations have been explored. Diagnosis of DIOS is based on suggestive symptoms, with a right lower quadrant mass confirmed on abdominal radiography, whereas symptoms of constipation are milder and of longer standing. In DIOS, early aggressive laxative treatment with oral laxatives (polyethylene glycol) or intestinal lavage with balanced osmotic electrolyte solution and rehydration is required, which now makes the need for surgical interventions rare. Constipation can generally be well controlled with polyethylene glycol maintenance treatment.

Genetic screening

Current approaches to genetic screening include newborn screening to identify infants who would benefit from early treatment, reproductive genetic screening to assist reproductive decision making, and family history assessment to identify individuals who would benefit from additional prevention measures. Although the traditional goal of screening is to identify early disease or risk in order to implement preventive therapy, genetic screening has always included an atypical element-information relevant to reproductive decisions. New technologies offer increasingly comprehensive identification of genetic conditions and susceptibilities. Tests based on these technologies are generating a different approach to screening that seeks to inform individuals about all of their genetic traits and susceptibilities for purposes that incorporate rapid diagnosis, family planning, and expediting of research, as well as the traditional screening goal of improving prevention. Use of these tests in population screening will increase the challenges already encountered in genetic screening programs, including false-positive and ambiguous test results, overdiagnosis, and incidental findings. Whether this approach is desirable requires further empiric research, but it also requires careful deliberation on the part of all concerned, including genomic researchers, clinicians, public health officials, health care payers, and especially those who will be the recipients of this novel screening approach.

Validation and use of a parametric model for projecting cystic fibrosis survivorship beyond observed data: a birth cohort analysis

Background

The current lifetable approach to survival estimation is favoured by CF registries. Recognising the limitation of this approach, we examined the utility of a parametric survival model to project birth cohort survival estimates beyond the follow-up period, where short duration of follow-up meant median survival estimates were indeterminable.

Methods

Parametric models were fitted to observed survivorship data from the US CF Foundation (CFF) Patient Registry 1980–1994 birth cohort. Model-predicted median survival was estimated. The best fitting model was applied to a Cystic Fibrosis Registry of Ireland dataset to allow an evaluation of the model's ability to estimate predicted median survival. This involved a comparison of birth cohort lifetable predicted and observed (Kaplan–Meier) median survival estimates.

Results

A Weibull model with main effects of gender and birth cohort was developed using a US CFF dataset (n=13 115) for which median survival was not directly estimable. Birth cohort lifetable predicted median survival for male and female patients born between 1985 and 1994 and surviving their first birthday was 50.9 and 42.4 years respectively. To evaluate the accuracy of a Weibull model in predicting median survival, a model was developed for the 1980–1984 Cystic Fibrosis Registry of Ireland birth cohort (n=243), which had an observed (Kaplan–Meier) median survival of 27.7 years. Model-predicted median survival estimates were calculated using data censored at different follow-up periods. The estimates converged to the true value as length of follow-up increased.

Conclusions

Accurate prognostic information that is clinically critical for care of patients affected by rare, life-limiting disorders can be provided by parametric survival models. Problems associated with short duration of follow-up for recent birth cohorts can be overcome using this approach, providing better opportunities to monitor survival and plan services locally.

High-intensity interval training in an adolescent with cystic fibrosis: a physiological perspective

Nutritional, musculoskeletal, and/or ventilatory status can lead to a decreased exercise capacity in children with cystic fibrosis (CF). Exercise training is already part of the usual care; however, the "optimal" intensity and volume of exercise training to improve exercise capacity is still unknown. Six weeks of high-intensity interval training (HIT) for a patient with CF with a ventilatory limitation was evaluated by a cardiopulmonary exercise test (CPET). Peak oxygen uptake and peak workload increased 19% and 16%, respectively, and there was a rise in peak ventilation from 50 L/min to 75 L/min, with an increase in both breathing depth and respiratory rate. A relative short period of HIT resulted in a significant increase in exercise capacity. In patients with CF, HIT might be an effective and efficient training regimen, especially in CF patients with a ventilatory limitation. Further research is necessary to investigate whether HIT is a better alternative than traditional aerobic training programs especially in ventilatory limited patients with CF.

Pharmacology, clinical efficacy and safety of recombinant human DNase in cystic fibrosis

Recombinant human DNase (rhDNase) is a mucolytic agent that is primarily used to improve mucociliary clearance in cystic fibrosis (CF). rhDNase is a recombinant human enzyme that is synthesized in a Chinese hamster ovary cell line. rhDNase enzymatically cleaves extracellular DNA into molecules of shorter length. CF sputum shows high concentrations of DNA released by disintegrating inflammatory cells. Free DNA contributes to the abnormally high viscosity of CF sputum and therefore forms an important target in the treatment of CF lung disease. Clinical studies have shown that daily nebulization of rhDNase is associated with an increase in lung function and a decrease in the frequency of exacerbations in patients with CF.

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 transplantation for cystic fibrosis

Lung transplantation is a complex, high-risk, potentially life-saving therapy for the end-stage lung disease of cystic fibrosis (CF). The decision to pursue transplantation involves comparing the likelihood of survival with and without transplantation as well as assessing the effect of wait-listing and transplantation on the patient's quality of life. Although recent population-based analyses of the US lung allocation system for the CF population have raised controversies about the survival benefits of transplantation, studies from the United Kingdom and Canada have suggested a definite survival advantage for those receiving transplants. In response to these and other controversies, leaders in transplantation and CF met together in Lansdowne, Virginia, to consider the state of the art in lung transplantation for CF in an international context, focusing on advances in surgical technique, measurement of outcomes, use of prognostic criteria, variations in local control over listing, and prioritization among the United States, Canada, the United Kingdom, and The Netherlands, patient adherence before and after transplantation and other issues in the broader context of lung transplantation. Finally, the conference members carefully considered how efforts to improve outcomes for lung transplantation for CF lung disease might best be studied. This Roundtable seeks to communicate the substance of our discussions.

Cystic fibrosis, aminoglycoside treatment and acute renal failure: the not so gentle micin

Aminoglycosides have a wide spectrum of gram-negative anti-bacterial activities and are available at low cost, which makes them commonly used drugs, especially for patients with cystic fibrosis (CF), who often suffer from chronic lung infections from Pseudomonas aeruginosa. Unfortunately, this treatment seems to have resulted in an increased incidence of acute renal failure (ARF) in patients with CF. A recent case-control study investigated risk factors for ARF in CF patients and suggested intravenous use of gentamicin as the prime culprit. Moreover, in most cases, at least one other risk factor, such as CF-related diabetes, pre-existing renal failure, dehydration or concurrent use of other nephrotoxic drugs, was present. We comment on the renal handling of aminoglycosides and the possible mechanisms of toxicity, as well as strategies for risk minimisation.

Planning the specialized care of adult congenital heart disease patients: from numbers to guidelines; an epidemiologic approach

Guidelines published in 2001 recommended 1 regional adult congenital heart disease (ACHD) center per 3 to 10 million population. Our objective was to determine if published guidelines on the numbers of regional ACHD centers are sufficient to meet the needs of adults with congenital heart disease in the general population. Population data were examined to evaluate the recommendations for the number of regional centers. We extrapolated a population prevalence of 4.09 per 1,000 adults corresponding to 847,896 and 87,375 patients with ACHD in the United States and Canada, respectively. We reviewed the information currently available on the numbers of ACHD facilities of any kind indexed to continental populations. We examined the distribution of disease and health services in pediatric and adult populations and examined the evidence for pressure points during the transition process. Published data on 6 of the largest regional ACHD centers were used to model regional center care. We reviewed determinants and recommendations for follow-up in regional centers. We explore 3 scenarios of referral patterns to regional centers, examining their impact of the number of centers required per country population. In conclusion, we demonstrate that 1 regional ACHD center for a population of 2.0 million adults appears to be closer to what is required for improving access to specialized care for patients with ACHD in the United States and Canada.

The prevalence of cystic fibrosis in the European Union

This study combined a variety of methods to determine the prevalence of cystic fibrosis in the European Union. The results of literature reviews, surveys, and registry analyses revealed a mean prevalence of 0.737/10,000 in the 27 EU countries, which is similar to the value of 0.797 in the United States, and only one outlier, namely the Republic of Ireland at 2.98.

Time trends in birth incidence of cystic fibrosis in two European areas: data from newborn screening programs

OBJECTIVE

To determine the incidence of cystic fibrosis (CF) and its time trends over a 16-year period (1990 to 2005) in 2 European regions with a long history of newborn screening (NBS) for CF, and to investigate the impact of some external factors.

STUDY DESIGN

This study focused on data from NBS and prenatal diagnosis (PD) in Brittany (western France) and Veneto/Trentino Alto-Adige (northeastern Italy).

RESULTS

Similar birth incidences of CF were observed in the 2 regions (1/3153 vs 1/3540; P = .245). Time trend analysis using Poisson regression revealed that the birth incidence decreased significantly in the Italian area only (average annual percent change [AAPC] = -4.7%; 95% confidence interval [CI] = -7.3 to -2; P = .0008). The use of PD appeared more common in Brittany, and considering the terminations of CF-affected fetuses, the adjusted incidence was 1/2191 in Brittany and 1/3116 in Veneto/Trentino, corresponding to variations of 30.5% (highly significant; P = .0002) and 12% (not significant; P = .16), respectively. Recording the reason for each PD allowed ready assessment of the affect of various public health policies on incidence. The affect of population mixing also appeared to be relevant in the Italian area.

CONCLUSIONS

This study highlights how the incidence of CF has evolved in 2 European regions that have different attitudes toward PD and immigration policy.

Prevalence and clinical significance of Staphylococcus aureus small-colony variants in cystic fibrosis lung disease

Small-colony variants (SCVs) of Staphylococcus aureus can be isolated from the chronically infected airways of patients suffering from cystic fibrosis (CF). These slow-growing morphological variants have been associated with persistent and antibiotic-resistant infections, such as osteomyelitis and device-related infections, but no information is available to date regarding the clinical significance of this special phenotype in CF lung disease. We therefore investigated the prevalence of S. aureus SCVs in CF lung disease in a 12-month prospective study and correlated the microbiological culture results with the patients' clinical data. A total of 252 patients were screened for the presence of SCVs. The prevalence rate was determined to be 17% (95% confidence interval, 10 to 25%) among S. aureus carriers. S. aureus isolates with the SCV phenotype showed significantly higher antibiotic resistance rates than those with the normal phenotype. Patients positive for SCVs were significantly older (P = 0.0099), more commonly cocolonized with Pseudomonas aeruginosa (P = 0.0454), and showed signs of more advanced disease, such as lower forced expiratory volume in 1 s (P = 0.0148) than patients harboring S. aureus with a solely normal phenotype. The logistic regression model determined lower weight (P = 0.016), advanced age (P = 0.000), and prior use of trimethoprim-sulfamethoxazole (P = 0.002) as independent risk factors for S. aureus SCV positivity. The clinical status of CF patients is known to be affected by multiple parameters. Nonetheless, the independent risk factors determined here point to the impact of S. aureus SCVs on chronic and persistent infections in advanced CF lung disease.

[Nephrolitiasis in a patient with cystic fibrosis]

Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Defects in the CFTR gene cause abnormal chloride conductance across the apical membrane of epithelial cells, which results in progressive lung disease and also affects other organs. Because life expectancy has increased, other complications of CF have become more apparent. We present a patient with CF and symptomatic nephrolithiasis. Several stones were evident in both kidneys. A 24-hour urine sample showed hyperoxaluria (141 mg/24 h/ 1.73 m(2)) and hypocitraturia and (206 mg/24 h/1.73 m(2), 177 mg citrate/g creatinine). Nephrolithiasis should be included in the differential diagnosis of patients with CF and abdominal pain; urinary excretion of oxalate and citrate should be investigated.

Outcome of assisted ventilation for acute respiratory failure in cystic fibrosis

OBJECTIVES

To assess outcome of assisted ventilation in cystic fibrosis (CF) patients with acute respiratory failure (ARF), to identify risk factors associated with poor outcome and to compare long-term outcome of CF children who were mechanically ventilated for ARF with unventilated CF controls.

DESIGN

Retrospective cohort study.

SETTING

Two large CF centres in the Netherlands.

PATIENTS

CF patients who required assisted ventilation for ARF and unventilated CF controls.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Thirty-one CF patients required assisted ventilation for ARF between January 1990 and March 2005. All five children (under 2 years of age) and seven adults (27%) survived. In the total population, age was a statistically significant risk factor for poor outcome (p=0.02). In adult CF patients who required invasive mechanical ventilation, acute on chronic respiratory failure was associated with poor outcome. In children who required mechanical ventilation for ARF, lung function and CF related complications 5 years later were not significantly different compared with controls matched for age, gender and genotype.

CONCLUSIONS

CF patients younger than 2 years old, who are ventilated because of ARF, have a good prognosis and their long-term outcome seems identical to unventilated CF controls. ARF in adult CF patients still is associated with high mortality, especially among patients with acute on chronic respiratory failure.