Anne L. Stephenson, MD, PhD; Jenna Sykes, MMath; Sanja Stanojevic, PhD; Bradley S. Quon, MD, MSc; Bruce C. Marshall, MD; Kristofer Petren, BA, BSc; Josh Ostrenga, MSc; Aliza K. Fink, DSc; Alexander Elbert, PhD; Christopher H. Goss, MD, MSc
Note: Dr. Stephenson had full access to all of the data in the study and takes responsibility for the integrity of the data, the accuracy of the data analysis, and the decision to submit the manuscript for publication.
Acknowledgment: The authors acknowledge the support of the U.S. Cystic Fibrosis Foundation and Cystic Fibrosis Canada, which made this study possible. They also acknowledge and thank all of the patients and families in the United States and Canada who consent to be part of their respective national cystic fibrosis patient registries, as well as the cystic fibrosis clinic staff who spend many hours inputting the data.
Grant Support: This study was funded by a Cystic Fibrosis Foundation grant (STEPHE14A0). Dr. Goss receives funding from the Cystic Fibrosis Foundation, the National Institutes of Health (grants R01HL103965, R01HL113382, R01AI101307, U M1HL119073, and P30DK089507), and the U.S. Food and Drug Administration (grant R01FD003704).
Disclosures: Dr. Stephenson reports grants from the Cystic Fibrosis Foundation during the conduct of the study and personal fees from Cystic Fibrosis Canada outside the submitted work. Ms. Sykes reports grants from the Cystic Fibrosis Foundation during the conduct of the study. Dr. Quon is supported by a Cystic Fibrosis Canada Clinician–Scientist Award, but Cystic Fibrosis Canada played no role in the study design or preparation of the manuscript. Dr. Goss reports board membership at KaloBios Pharmaceuticals and Boehringer Ingelheim; consultancy for Vertex Pharmaceuticals and Novartis; grants from Vertex Pharmaceuticals, the Cystic Fibrosis Foundation, the National Institutes of Health, and the U.S. Food and Drug Administration; speaking fees from Hoffmann–La Roche, Johns Hopkins University, the European Cystic Fibrosis Society, and Medscape; and an honorarium from Gilead Sciences. Authors not named here have disclosed no conflicts of interest. Disclosures can also be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M16-0858.
Editors' Disclosures: Christine Laine, MD, MPH, Editor in Chief, reports that she has no financial relationships or interests to disclose. Darren B. Taichman, MD, PhD, Executive Deputy Editor, reports that he has no financial relationships or interests to disclose. Cynthia D. Mulrow, MD, MSc, Senior Deputy Editor, reports that she has no relationships or interests to disclose. Deborah Cotton, MD, MPH, Deputy Editor, reports that she has no financial relationships or interest to disclose. Jaya K. Rao, MD, MHS, Deputy Editor, reports that she has stock holdings/options in Eli Lilly and Pfizer. Sankey V. Williams, MD, Deputy Editor, reports that he has no financial relationships or interests to disclose. Catharine B. Stack, PhD, MS, Deputy Editor for Statistics, reports that she has stock holdings in Pfizer and Johnson & Johnson.
Reproducible Research Statement:Study protocol: Not available. Statistical code: Available from Dr. Stephenson (e-mail, email@example.com). Data set: Available upon request from the Cystic Fibrosis Foundation and Cystic Fibrosis Canada.
Requests for Single Reprints: Anne L. Stephenson, MD, PhD, St. Michael's Hospital, 30 Bond Street, 6th Floor, Bond Wing, Toronto, Ontario M5B 1W8, Canada; e-mail: firstname.lastname@example.org.
Current Author Addresses: Dr. Stephenson and Ms. Sykes: St. Michael's Hospital, 30 Bond Street, 6th Floor, Bond Wing, Toronto, Ontario M5B 1W8, Canada.
Dr. Stanojevic: Institute of Health Policy, Management and Evaluation, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M6, Canada.
Dr. Quon: Centre for Heart Lung Innovation, Department of Medicine, University of British Columbia, #166–1081 Burrard Street, Vancouver, British Columbia V6Z 1Y6, Canada.
Drs. Marshall, Fink, and Elbert; Mr. Petren; and Mr. Ostrenga: Cystic Fibrosis Foundation, 6931 Arlington Road, Bethesda, MD 20814.
Dr. Goss: Division of Pulmonary and Critical Care Medicine, Department of Medicine and Pediatrics, University of Washington Medical Center, 1959 Northeast Pacific Street, Seattle, WA 98195.
Author Contributions: Conception and design: A.L. Stephenson, S. Stanojevic, B.S. Quon, B.C. Marshall, A. Fink, C.H. Goss.
Analysis and interpretation of the data: A.L. Stephenson, J. Sykes, S. Stanojevic, B.S. Quon, K. Petren, A. Fink, A. Elbert, C.H. Goss.
Drafting of the article: A.L. Stephenson, S. Stanojevic, B.S. Quon, C.H. Goss.
Critical revision for important intellectual content: A.L. Stephenson, J. Sykes, S. Stanojevic, B.S. Quon, C.H. Goss.
Final approval of the article: A.L. Stephenson, J. Sykes, S. Stanojevic, B.S. Quon, B.C. Marshall, K. Petren, J. Ostrenga, A. Fink, A. Elbert, C.H. Goss.
Statistical expertise: J. Sykes, S. Stanojevic, J. Ostrenga, C.H. Goss.
Obtaining of funding: A.L. Stephenson, S. Stanojevic, B.S. Quon, C.H. Goss.
Administrative, technical, or logistic support: A.L. Stephenson, K. Petren, A. Elbert.
Collection and assembly of data: A.L. Stephenson, J. Sykes, K. Petren, J. Ostrenga, A. Elbert.
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.
To use a standardized approach to calculate cystic fibrosis survival estimates and to explore differences between Canada and the United States.
42 Canadian cystic fibrosis clinics and 110 U.S. cystic fibrosis care centers.
Patients followed in the Canadian Cystic Fibrosis Registry (CCFR) and U.S. Cystic Fibrosis Foundation Patient Registry (CFFPR) between 1990 and 2013.
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.
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.
Ascertainment bias due to missing data or nonrandom loss to follow-up might affect the results.
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.
U.S. Cystic Fibrosis Foundation.
Stephenson AL, Sykes J, Stanojevic S, Quon BS, Marshall BC, Petren K, et al. Survival Comparison of Patients With Cystic Fibrosis in Canada and the United States: A Population-Based Cohort Study. Ann Intern Med. ;166:537–546. doi: 10.7326/M16-0858
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Published: Ann Intern Med. 2017;166(8):537-546.
Published at www.annals.org on 14 March 2017
Gastroenterology/Hepatology, Pancreatic Disease, Pulmonary/Critical Care.
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