Survival and Lung Transplant Outcomes for Individuals With Advanced Cystic Fibrosis Lung Disease Living in the United States and Canada: An Analysis of National Registries.

BACKGROUND: Understanding how health outcomes differ for patients with advanced cystic fibrosis (CF) lung disease living in the United States compared with Canada has health policy implications. RESEARCH QUESTION: What are rates of lung transplant (LTx) and rates of death without LTx in the United States and Canada among individuals with FEV1 < 40% predicted? STUDY DESIGN AND METHODS: This was a retrospective population-based cohort study, 2005 to 2016, using the US CF Foundation, United Network for Organ Sharing, and Canadian CF registries. Individuals with CF and at least two FEV1 measurements < 40% predicted within a 5-year period, age ≥ 6 years, without prior LTx were included. Multivariable competing risk regression for time to death without LTx (LTx as a competing risk) and time to LTx (death as a competing risk) was performed. RESULTS: There were 5,899 patients (53% male) and 905 patients (54% male) with CF with FEV1 < 40% predicted living in the United States and Canada, respectively. Multivariable competing risk regression models identified an increased risk of death without LTx (hazard ratio [HR], 1.79; 95% CI, 1.52-2.1) and decreased LTx (HR, 0.66; 95% CI, 0.58-0.74) among individuals in the United States compared with Canada. More pronounced differences were seen in the patients in the United States with Medicaid/Medicare insurance compared with Canadians (multivariable HR for death without LTx, 2.24 [95% CI, 1.89-2.64]; multivariable HR for LTx, 0.54 [95% CI, 0.47-0.61]). Patients of nonwhite race were also disadvantaged (multivariable HR for death without LTx, 1.56 [95% CI, 1.32-1.84]; multivariable HR for LTx, 0.47 [95% CI, 0.36-0.62]). INTERPRETATION: There are lower rates of LTx and an increased risk of death without LTx for US patients with CF with FEV1 < 40% predicted compared with Canadian patients. Findings are more striking among US patients with CF with Medicaid/Medicare health insurance, and nonwhite patients in both countries, raising concerns about underuse of LTx among vulnerable populations.

Bridging the survival gap in cystic fibrosis: An investigation of lung transplant outcomes in Canada and the United States.

BACKGROUND: Previous literature in cystic fibrosis (CF) has shown a 10-year survival gap between Canada and the United States (US). We hypothesized that differential access to and survival after lung transplantation may contribute to the observed gap. The objectives of this study were to compare CF transplant outcomes between Canada and the US and estimate the potential contribution of transplantation to the survival gap. METHODS: Data from the Canadian CF Registry and the US Cystic Fibrosis Foundation Patient Registry supplemented with data from United Network for Organ Sharing were used. The probability of surviving after transplantation between 2005 and 2016 was calculated using the Kaplan‒Meier method. Survival by insurance status at the time of transplantation and transplant center volume in the US were compared with those in Canada using Cox proportional hazard models. Simulations were used to estimate the contribution of transplantation to the survival gap. RESULTS: Between 2005 and 2016, there were 2,653 patients in the US and 470 in Canada who underwent lung transplantation for CF. The 1-, 3-, and 5-year survival rates were 88.3%, 71.8%, and 60.3%, respectively, in the US compared with 90.5%, 79.9%, and 69.7%, respectively, in Canada. Patients in the US were also more likely to die on the waitlist (p < 0.01) than patients in Canada. If the proportion of who underwent transplantation and post-transplant survival in the US were to increase to those observed in Canada, we estimate that the survival gap would decrease from 10.8 years to 7.5 years. CONCLUSIONS: Differences in waitlist mortality and post-transplant survival can explain up to a third of the survival gap observed between the US and Canada.

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.

Risk Factors for Gaps in Care during Transfer from Pediatric to Adult Cystic Fibrosis Programs in the United States.

RATIONALE: With improved survival into adulthood, the number of dedicated adult cystic fibrosis (CF) care programs has expanded in the United States over the past decade. Transfer from pediatric to adult CF programs represents a potential time for lapses in recommended health care. OBJECTIVES: To describe variability in transfer between pediatric and adult CF care programs and to identify factors associated with prolonged gaps in care. METHODS: Using the U.S. CF Foundation Patient Registry, we identified individuals with CF who transferred care from a pediatric to an adult CF care program during 2007 to 2013. A gap in care was defined as the time in days between the last recorded pediatric encounter and the first recorded adult encounter. A hierarchical multivariable regression model was applied to investigate the effect of program- and patient-level factors on gaps in care. RESULTS: There were 1,946 individuals at 155 pediatric CF programs who transferred to an adult CF program during the analytic period. The mean age at transfer was 21.1 years, with 68% transferring care between ages 18 and 21 years. The mean gap in care during transfer was 183 days (median, 106 d; range, 2-1,843 d); 47% had a less than 100-day gap, and 13% had a greater than or equal to 365-day gap (prolonged gap). Prolonged gaps in care were more likely to occur among those younger than age 18 years (odds ratio, 3.33; 95% confidence interval, 2.06-5.37) at the time of transfer and those who transferred to an adult program that was in a different city from their pediatric or affiliate program (odds ratio, 2.16; 95% confidence interval, 1.48-3.17). Having any health insurance coverage was associated with decreased likelihood of prolonged gaps (private insurance vs. no insurance [odds ratio, 0.15; 95% confidence interval, 0.09-0.23] or any government insurance versus no insurance [odds ratio, 0.11; 95% confidence interval, 0.07-0.18]). Lung function, nutritional status, and receipt of intravenous antibiotics in the final year of pediatric care were not associated with the length of gap in care during transfer. CONCLUSIONS: In the United States, the majority of individuals transferring from pediatric to adult CF care do so between ages 18 and 21 years. A minority had a gap greater than or equal to 365 days during transfer to adult care, suggesting that most did not have a disruption in recommended quarterly care visits during the transfer period. Risk factors for prolonged gaps in care include younger age at transfer, lack of health insurance, and relocation. Care coordination during transition in CF may minimize lapses in care by identifying and more closely addressing the needs of individuals at highest risk.

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.

Outcomes of infants with indeterminate diagnosis detected by cystic fibrosis newborn screening.

BACKGROUND AND OBJECTIVES: Cystic fibrosis transmembrane conductance regulator-related metabolic syndrome (CRMS) describes asymptomatic infants with a positive cystic fibrosis (CF) newborn screen (NBS) but inconclusive diagnostic testing for CF. Little is known about the epidemiology and outcomes of CRMS. The goal of this study was to determine the prevalence, clinical features, and short-term outcomes of infants with CRMS. METHODS: We analyzed data from the US CF Foundation Patient Registry (CFFPR) from 2010 to 2012. We compared demographic, diagnostic, anthropometric, health care utilization, microbiology, and treatment characteristics between infants with CF and infants with CRMS. RESULTS: There were 1983 infants diagnosed via NBS between 2010 and 2012 reported to the CFFPR. By using the CF Foundation guideline definitions, 1540 and 309 infants met the criteria for CF and CRMS, respectively (CF:CRMS ratio = 5.0:1.0). Of note, 40.8% of infants with CRMS were entered into the registry with a clinical diagnosis of CF. Infants with CRMS tended to have normal nutritional indices. However, 11% of infants with CRMS had a positive Pseudomonas aeruginosa respiratory tract culture in the first year of life. CONCLUSIONS: CRMS is a common outcome of CF NBS, and some infants with CRMS may develop features concerning for CF disease. A substantial proportion of infants with CRMS were assigned a clinical diagnosis of CF, which may reflect misclassification or clinical features not collected in the CFFPR.

Children and young adults with CF in the USA have better lung function compared with the UK.

BACKGROUND: People with cystic fibrosis (CF) are managed differently in the USA and UK providing an opportunity to learn from differences in practice patterns. OBJECTIVES: To compare cross-sectional demographics, practice patterns and clinical outcomes between US and UK CF patients. METHODS: This was a cross-sectional study using 2010 data from patients in the US Cystic Fibrosis Foundation and the UK Cystic Fibrosis patient registries. The a priori outcome measures of interest were lung function and nutritional status. Descriptive statistics and two sample comparisons were performed. Stratification and multivariable linear regression were used to adjust for confounding. RESULTS: The study cohort included 13 777 children and 11 058 adults from the USA and 3968 children and 3965 adults from the UK. In children, mean body mass index centiles were similar. Lung function (FEV1 and FVC% predicted) was significantly higher in US patients ages 6-25 years of age. In a regression model adjusted for only age, FEV1% predicted was on average 3.31% of predicted (95% CI 2.65 to 3.96) higher in the USA compared with the UK. When adjusted for age, age at diagnosis, gender, pancreatic insufficiency and genotype, FEV1% predicted was on average 3.03% of predicted (95% CI 2.37 to 3.69) higher in the USA compared with the UK These differences persisted despite adjustment for possible confounders. Hypertonic saline and dornase alfa were much more commonly prescribed in US children. CONCLUSIONS: Children and young adults with CF have better lung function in the USA compared with the UK despite similar nutritional status.

Sustained improvement in nutritional outcomes at two paediatric cystic fibrosis centres after quality improvement collaboratives.

OBJECTIVE: To describe the characteristics of sustained improved nutritional outcomes through the use of quality improvement (QI) methodology. DESIGN: Retrospective analysis of a QI intervention in two institutions, implemented as part of larger national collaboratives. SETTING: Paediatric cystic fibrosis (CF) programmes in academic centres in Alabama and Illinois. PARTICIPANTS: All paediatric patients enrolled in the CF Foundation (CFF) Patient Data Registry were included. INTERVENTIONS: Improved and sustained nutrition outcomes occurred through implementation of the CFF practice guidelines for CF nutrition management via care delivery processes, nutritional interventions, team engagement and data display. MEASUREMENT: Mean body mass index (BMI) percentile, percentage of patients less than 50th percentile and percentage less than 10th percentile for all patients aged 2-20 years were tracked through run charts and statistical process control charts. Mann-Whitney U and χ(2) tests were used to determine significance between each centre and national outcomes. RESULTS: Each centre achieved rapid improvement in mean BMI percentile in patients, one centre rising from the 40th percentile in 2001 to the 49th percentile in 2003, the other rising from the 37th percentile in 2003 to the 45th percentile in 2004. These centres have also maintained improved nutritional outcomes, so that they were at the 60th and 55th percentiles, respectively, in 2011. Sustained improvement was accomplished through QI methodology, use of data as a driver for improvement and a change in culture. CONCLUSIONS: Participation in collaboratives led to improved nutrition outcomes while a strong culture of QI facilitated sustained improvement.