Registry-based study in people with cystic fibrosis and an R117H variant treated with ivacaftor.

BACKGROUND: Ivacaftor approval was extended to people with cystic fibrosis (CF) and an R117H variant in 2014 in the USA. This observational, real-world, postapproval study evaluated long-term outcomes among people with CF and an R117H variant on ivacaftor using data from the US Cystic Fibrosis Foundation Patient Registry. METHODS: Key outcomes were evaluated in ivacaftor-treated people with CF and an R117H variant for up to 36 months before and after treatment initiation using within-group comparisons. Analyses were descriptive in nature, focused on evaluation of observed outcome patterns over time and were performed both overall and for age groups ≥2 to <6 years, ≥6 to <18 years and ≥18 years. Key outcomes included lung function, body mass index (BMI), pulmonary exacerbations (PEx) and hospitalisations. RESULTS: The ivacaftor cohort included 369 people with CF and an R117H variant who initiated therapy between 1 January 2015 and 31 December 2016. During each of the 12-month intervals following treatment initiation, the mean observed percent predicted forced expiratory volume in 1 s (ppFEV1) and BMI values were higher and the mean annualised number of PEx and hospitalisation events were lower than pretreatment values. Mean change in ppFEV1 from pretreatment baseline was an increase of 1.5 (95% CI 0.8 to 2.3), 1.7 (95% CI 0.7 to 2.7) and 1.8 (95% CI 0.6 to 3.0) percentage points in the first, second and third years of treatment, respectively. Similar trends were observed in adult and paediatric subgroups. CONCLUSIONS: The results support the clinical effectiveness of ivacaftor in people with CF and an R117H variant, including adult and paediatric subgroups.

Real-world safety and effectiveness of elexacaftor/tezacaftor/ivacaftor in people with cystic fibrosis: Interim results of a long-term registry-based study.

BACKGROUND: Phase 3 clinical trials showed elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) was safe and efficacious in people with cystic fibrosis (CF) with ≥1 F508del-CFTR allele. To assess long-term effects of ELX/TEZ/IVA under real-world conditions of use, a 5-year observational registry-based study is being conducted. We report interim results from the first 2 years of follow-up. METHODS: The study included people with CF in the US Cystic Fibrosis Foundation Patient Registry (CFFPR) who initiated ELX/TEZ/IVA between October 2019 and December 2020. Pulmonary exacerbations (PEx), percent predicted forced expiratory volume in 1 second (ppFEV1), hospitalizations, bacterial pathogens, body mass index (BMI), CF complications and comorbidities, and liver function tests (LFTs) after treatment initiation were compared with the 5-year pre-treatment period. Death and lung transplantation were assessed relative to 2019 CFFPR data. RESULTS: 16,116 people with CF were included (mean treatment duration 20.4 months). Among those with 5 years of pre-treatment data, mean PEx/patient/year declined to 0.18 (95% CI: 0.17, 0.19) in Years 1 and 2 post-treatment from 0.86 (95% CI: 0.83, 0.88) in the baseline year (79% reduction), after a continued increase observed pre-treatment. Similarly, a decline in mean hospitalizations/patient/year was observed in Year 1 that was sustained in Year 2 (74% reduction from baseline year). The mean absolute change in ppFEV1 from baseline was +8.2 percentage points (95% CI: 8.0, 8.4) in Year 1 and +8.9 percentage points (95% CI: 8.7, 9.1) in Year 2, after a continued decline observed pre-treatment. Positive bacterial cultures decreased for all evaluated pathogens, and mean BMI increased by 1.6 kg/m2 (95% CI: 1.5, 1.6) by Year 2. No new safety concerns were identified based on evaluation of CF complications, comorbidities, and LFTs. The annualized rates of death (0.47% [95% CI: 0.39, 0.55]) and lung transplantation (0.16% [95% CI: 0.12, 0.22]) were considerably lower than reported in 2019 (1.65% and 1.08%, respectively). CONCLUSIONS: ELX/TEZ/IVA treatment was associated with sustained improvements in lung function, reduced frequency of PEx and all-cause hospitalization, increased BMI, and lower prevalence of positive bacterial cultures. Additionally, there was a 72% lower rate of death and 85% lower rate of lung transplantation relative to the year before ELX/TEZ/IVA availability. These results, from the largest cohort of ELX/TEZ/IVA-treated people to date, extend our understanding of the broad clinical benefits of ELX/TEZ/IVA.

Contemporary cystic fibrosis incidence rates in Canada and the United States.

BACKGROUND: The availability of new diagnostic algorithms for cystic fibrosis (CF), changing population demographics and programs that impact family planning decisions can influence incidence rates. Thus, previously reported incidence rates in Canada and the United States (US) may be outdated. The objectives of this study were to estimate contemporary CF incidence rates in Canada and the US and to determine if the incidence rate has changed over time. METHOD: This population-based cohort study utilized data between 1995-2019 from the Canadian CF Registry (CCFR), Statistics Canada, US CF Foundation Patient Registry (CFFPR) data, and US Center for Disease Control (CDC) National Vital Statistics System. Incidence was estimated using the number of live CF births by year, sex, and geographic region using Poisson regression, with the number of live births used as the denominator. To account for delayed diagnoses, we imputed the proportion of diagnoses expected given historical trends, and varying rates of newborn screening (NBS) implementation by region. RESULTS: After accounting for implementation of NBS and delayed diagnoses, the estimated incidence rate for CF in 2019 was 1:3848 (95% CI: 1:3574, 1:4143) live births in Canada compared to 1:5130 (95% CI:1:4996, 1:5267) in the US. There was substantial regional variation in incidence rates within both Canada and the US. Since 1995, incidence rates have decreased at a rate of 1.6% per year in both countries (p<0.001). CONCLUSION: Contemporary CF incidence rates suggest CF incidence is lower than previously reported and varies widely within North America. This information is important for resource planning and for tracking how programs (e.g., genetic counselling, modulator availability etc.) may impact the incidence of CF moving forward.

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

Importance: Newborn screening (NBS) for cystic fibrosis (CF) has been universal in the US since 2010, but its association with clinical outcomes is unclear. Objective: To describe the real-world effectiveness of NBS programs for CF in the US on outcomes up to age 10 years. Design, Setting, and Participants: This was a retrospective cohort study using CF Foundation Patient Registry data from January 1, 2000, to December 31, 2018. The staggered implementation of NBS programs by state was used to compare longitudinal outcomes among children in the same birth cohort born before vs after the implementation of NBS for CF in their state of birth. Participants included children with an established diagnosis of CF born between January 1, 2000, to December 31, 2018, in any of the 44 states that implemented NBS for CF between 2003 and 2010. Data were analyzed from October 5, 2020, to April 22, 2022. Exposures: Birth before vs after the implementation of NBS for CF in the state of birth. Main Outcomes and Measures: Longitudinal trajectory of height and weight percentiles from diagnosis, lung function (forced expiratory volume in 1 second, [FEV1] percent predicted) from age 6 years, and age at initial and chronic infection with Pseudomonas aeruginosa using linear mixed-effects and time-to-event models adjusting for birth cohort and potential confounders. Results: A total of 9571 participants (4713 female participants [49.2%]) were eligible for inclusion, with 4510 (47.1%) in the pre-NBS cohort. NBS was associated with higher weight and height percentiles in the first year of life (weight, 6.0; 95% CI, 3.1-8.4; height, 6.6; 95% CI, 3.8-9.3), but these differences decreased with age. There was no association between NBS and FEV1 at age 6 years, but the percent-predicted FEV1 did increase more rapidly with age in the post-NBS cohort. NBS was associated with older age at chronic P aeruginosa infection (hazard ratio, 0.69; 95% CI, 0.54-0.89) but not initial P aeruginosa infection (hazard ratio, 0.88; 95% CI, 0.77-1.01). Conclusions and Relevance: NBS for CF in the US was associated with improved nutritional status up to age 10 years, a more rapid increase in lung function, and delayed chronic P aeruginosa infection. In the future, as highly effective modulator therapies become available for infants with CF, NBS will allow for presymptomatic initiation of these disease-modifying therapies before irreversible organ damage.

Bone mineral density screening by DXA for people with cystic fibrosis: A registry analysis of patient and program factors influencing rates of screening.

BACKGROUND: Current guidelines recommend screening for Cystic Fibrosis (CF) related bone disease (CFBD) using dual-energy x-ray absorptiometry (DXA) for all people ≥ 18 years of age and select people ≥ 8 years of age. However, adherence to these guidelines is variable. This study aims to evaluate screening practices among adult programs in the US and identify patient and program-based characteristics which may influence screening. METHODS: The CF Foundation Patient Registry (CFFPR) was used to identify all people over the age of 18 who were seen at adult CF programs and received screening for CFBD using DXA at least once between 2014 and 2018. Associations with patient and program level characteristics were assessed using the Chi Square test. Patient level variables were also examined using standardized difference to assess for meaningful clinical differences in rates of screening. RESULTS: From 2014 to 2018, a total of 15,134 people over the age of 18 were identified in the CFFPR. Of these people, 9,023 (60%) received a DXA during the time period. The median rate of screening by program was 66% and programs in the highest quartile of screening obtained DXAs on >76% of their population. At the program level, larger size and increased adherence to other guideline practices such as OGTT screening and 4 visits, 4 cultures in a year correlated with higher rates of screening for CFBD. At the patient-level, people with lower lung function (FEV1 <90%) and those with CF related diabetes were more likely to be screened. People without health insurance were less likely to receive recommended screening. CONCLUSION: Screening practices for CFBD vary widely across adult programs in the US despite recommendations to screen all people over the age of 18. Factors identified in this analysis may be used to identify those people at highest risk of missing appropriate screening. CFBD has significant implications for our patients and therefore routine screening should be emphasized as part of standard care moving forward.

Lung function in children with cystic fibrosis in the USA and UK: a comparative longitudinal analysis of national registry data.

RATIONALE: A previous analysis found significantly higher lung function in the US paediatric cystic fibrosis (CF) population compared with the UK with this difference apparently decreasing in adolescence and adulthood. However, the cross-sectional nature of the study makes it hard to interpret these results. OBJECTIVES: To compare longitudinal trajectories of lung function in children with CF between the USA and UK and to explore reasons for any differences. METHODS: We used mixed effects regression analysis to model lung function trajectories in the study populations. Using descriptive statistics, we compared early growth and nutrition (height, weight, body mass index), infections (Pseudomonas aeruginosa, Staphylococcus aureus) and treatments (rhDnase, hypertonic saline, inhaled antibiotics). RESULTS: We included 9463 children from the USA and 3055 children from the UK with homozygous F508del genotype. Lung function was higher in the USA than in the UK when first measured at age six and remained higher throughout childhood. We did not find important differences in early growth and nutrition, or P.aeruginosa infection. Prescription of rhDNase and hypertonic saline was more common in the USA. Inhaled antibiotics were prescribed at similar levels in both countries, but Tobramycin was prescribed more in the USA and colistin in the UK. S. aureus infection was more common in the USA than the UK. CONCLUSIONS: Children with CF and homozygous F508del genotype in the USA had better lung function than UK children. These differences do not appear to be explained by early growth or nutrition, but differences in the use of early treatments need further investigation.

Clinical characteristics of cystic fibrosis patients prior to lung transplantation: An international comparison between Canada and the United States.

BACKGROUND: Cystic fibrosis (CF) patients from Canada have better-reported post-lung transplant survival compared to patients from the United States. We hypothesized the clinical characteristics of CF patients prior to lung transplant differ between the two countries. METHODS: Population-based cohort study utilizing combined Canadian CF Registry and US CF Foundation Patient Registry data from 1986 to 2013. Demographic and clinical variables were analyzed prior to lung transplant. RESULTS: Between 1986 and 2013, 607 (10.2%) CF patients underwent lung transplantation in Canada and 3428 (7.5%) in the United States. A lower proportion of recipients had growth of B. cepacia complex prior to transplant in the United States compared to Canada (0.8% vs 4.3%). Lung function was similar between recipients from the two countries. The proportion of patients classified as underweight was significantly higher in the United States compared to Canada (39.8% vs 28.0%; SD 26.1) despite higher rates of feeding tube use (42.5% vs 28.6%; SD 29.0). CONCLUSIONS: CF lung transplant recipients from the United States have similar lung function, lower rates of B. cepacia complex, and worse nutritional parameters prior to transplant compared to counterparts in Canada. Future studies are necessary to evaluate the impact of these differences on post-transplant survival.

Comparison of Nutrition and Lung Function Outcomes in Patients with Cystic Fibrosis Living in Canada and the United States.

RATIONALE: A 10-year gap in the median age of survival for patients with cystic fibrosis (CF) was reported between patients living in Canada compared with patients living in the United States. OBJECTIVES: Because both malnutrition and poor lung function are associated with an increased risk of mortality in CF, we investigated the temporal and longitudinal trends in lung function and nutrition between Canada and the United States. METHODS: This cohort study used Canadian CF Registry and U.S. CF Foundation Patient Registry data from 1990 to 2013. A unified dataset was created to harmonize the variables collected within the two registries for the purpose of comparing outcomes between the two countries. MEASUREMENTS AND MAIN RESULTS: We conducted three analyses: survival differences by birth cohort; population trends for FEV1 and body mass index (BMI) over time; and individual patient FEV1 and BMI trajectories. The study included a total of 37,772 patients in the United States and 5,149 patients in Canada. Patients with CF experienced significant improvements in nutritional status and lung function in both Canada and the United States during the study. In addition, the survival gap between the two countries is narrowing within younger birth cohorts. The improvements for the patients within the United States were most prominent in the BMI trajectories, where patients born after 1990 in the United States have higher BMI that has persisted over time. CONCLUSIONS: The reasons for the observed improvements, and catch-up in the United States, are likely multifactorial and include the introduction of high-fat, high-calorie diets; introduction of newborn screening; and/or improved access to care for CF children in the United States.

Survival Comparison of Patients With Cystic Fibrosis in Canada and the United States: A Population-Based Cohort Study.

BACKGROUND: In 2011, the median age of survival of patients with cystic fibrosis reported in the United States was 36.8 years, compared with 48.5 years in Canada. Direct comparison of survival estimates between national registries is challenging because of inherent differences in methodologies used, data processing techniques, and ascertainment bias. OBJECTIVE: To use a standardized approach to calculate cystic fibrosis survival estimates and to explore differences between Canada and the United States. DESIGN: Population-based study. SETTING: 42 Canadian cystic fibrosis clinics and 110 U.S. cystic fibrosis care centers. PATIENTS: Patients followed in the Canadian Cystic Fibrosis Registry (CCFR) and U.S. Cystic Fibrosis Foundation Patient Registry (CFFPR) between 1990 and 2013. MEASUREMENTS: Cox proportional hazards models were used to compare survival between patients followed in the CCFR (n = 5941) and those in the CFFPR (n = 45 448). Multivariable models were used to adjust for factors known to be associated with survival. RESULTS: Median age of survival in patients with cystic fibrosis increased in both countries between 1990 and 2013; however, in 1995 and 2005, survival in Canada increased at a faster rate than in the United States (P < 0.001). On the basis of contemporary data from 2009 to 2013, the median age of survival in Canada was 10 years greater than in the United States (50.9 vs. 40.6 years, respectively). The adjusted risk for death was 34% lower in Canada than the United States (hazard ratio, 0.66 [95% CI, 0.54 to 0.81]). A greater proportion of patients in Canada received transplants (10.3% vs. 6.5%, respectively [standardized difference, 13.7]). Differences in survival between U.S. and Canadian patients varied according to U.S. patients' insurance status. LIMITATION: Ascertainment bias due to missing data or nonrandom loss to follow-up might affect the results. CONCLUSION: Differences in cystic fibrosis survival between Canada and the United States persisted after adjustment for risk factors associated with survival, except for private-insurance status among U.S. patients. Differential access to transplantation, increased posttransplant survival, and differences in health care systems may, in part, explain the Canadian survival advantage. PRIMARY FUNDING SOURCE: U.S. Cystic Fibrosis Foundation.

The Cystic Fibrosis Foundation Patient Registry. Design and Methods of a National Observational Disease Registry.

RATIONALE: The Cystic Fibrosis Foundation Patient Registry (CFFPR) is an ongoing patient registry study that collects longitudinal demographic, clinical, and treatment information about persons with cystic fibrosis (CF) in the United States. CF is a life-shortening genetic disorder that occurs in approximately 1 in 3,500 births in the United States. High-quality observational data is important for clinical research, quality improvement, and clinical management. OBJECTIVES: To describe the data collection, patient population, and key limitations of the CFFPR. METHODS: Inclusion criteria for the CFFPR include diagnosis with CF or a CFTR-associated disorder, care at an accredited care center program, and provision of informed consent. Data from clinic visits and hospitalizations are collected through a secure website. Loss to follow-up and generalizability were examined using several methods. The accuracy of CFFPR data was evaluated with an audit of 2012 CFFPR data compared to the medical record. MEASUREMENTS AND MAIN RESULTS: Since 1986, the CFFPR contains the records of 48,463 individuals with CF. Participation among individuals seen at accredited care centers is high, and loss to follow-up is low. An audit of 2012 CFFPR data suggests that the CFFPR contains 95% of clinic visits and 90% of hospitalizations found in the medical record for these patients, and nearly all of the audited fields were highly accurate. CONCLUSIONS: Registries such as the CFFPR are important tools for research, clinical care, and tracking incidence, mortality and population trends.

A standardized approach to estimating survival statistics for population-based cystic fibrosis registry cohorts.

OBJECTIVES: Our objective was to quantify the effect of different statistical techniques, inclusion/exclusion criteria, and missing data on the predicted median survival age. STUDY DESIGN AND SETTING: Using the Canadian cystic fibrosis registry (CCFR), the median age of survival was calculated using both the Cox proportional hazards (PH) and the life-table methods. Through simulations, we examined how the median age of survival would change when: (1) patients were excluded, (2) death dates were inaccurate, (3) patients were lost to follow-up, (4) entire years with no clinic visits were excluded even if the​ patient had a visit in subsequent years, and (5) censoring patients at their date of transplant. Simulations were run assuming 5-35% of data were affected by each scenario. RESULTS: Over the period 2009-2013, there were 4,666 individuals in the CCFR with 240 deaths. The observed median age of survival calculated by the Cox PH method was 50.9 [95% confidence interval (CI): 47.4, 54.3] and 50.5 from the life-table method (95% CI: 47.5, 53.5). Censoring patients at their transplant date overestimated the median age of survival by 7.2 years (58.1; 95% CI: 53.3, 64.7). Simulations determined that by missing just 15% of deaths, the median age of survival can be overestimated by 3.5 years (54.4; 95% CI: 54.2, 56.1), and having 25% of patients lost to follow-up can underestimate the median age of survival by 3.3 years (47.6; 95% CI: 46.8, 47.7). CONCLUSION: We present several recommendations to assist national cystic fibrosis registries in calculating and reporting the median age of survival in a standardized fashion. It is imperative to state the statistical method used as well as the proportion lost to follow-up and the treatment of missing data and transplanted patients. Registries must be diligent in their data collection as incomplete data can lead to overestimation and underestimation of survival.