The St. George's Respiratory Questionnaire Definition of Chronic Bronchitis May Be a Better Predictor of COPD Exacerbations Compared With the Classic Definition

COPDGene Investigators

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Background: Chronic bronchitis (CB) increases risk of COPD exacerbations. We have shown that the St. George's Respiratory Questionnaire (SGRQ) CB definition identifies patients with a similar clinical phenotype as classically defined CB. Whether the SGRQ CB definition is a predictor of future COPD exacerbations is unknown. Methods: We analyzed 7,557 smokers with normal spirometry and Global Initiative for Chronic Obstructive Lung Disease stage 1-4 COPD in the Genetic Epidemiology of COPD study with longitudinal follow-up data on exacerbations. Subjects were divided into classic CB+ or classic CB, using the classic definition. In addition, subjects were divided into SGRQ CB+ or SGRQ CB. Exacerbation frequency and severe exacerbation frequency were determined in each group. Multivariable linear regressions were performed for exacerbation frequency with either classic CB or SGRQ CB and relevant covariates. Results: There were 1,434 classic CB+ subjects and 2,290 SGRQ CB+ subjects. The classic CB+ group had a greater exacerbation frequency compared with the classic CB group (0.69 ± 1.26 vs 0.36 ± 0.90 exacerbations per patient per year; P < .0001) and a greater severe exacerbation frequency (0.26 ± 0.74 vs 0.13 ± 0.46 severe exacerbations per patient per year; P < .0001). There were similar differences between the SGRQ CB+ and SGRQ CB groups. In multivariable analysis, both SGRQ CB and classic CB were independent predictors of exacerbation frequency, but SGRQ CB had a higher regression coefficient. In addition, SGRQ CB was an independent predictor of severe exacerbation frequency whereas classic CB was not. Conclusions: The SGRQ CB definition identified more subjects at risk for future exacerbations than the classic CB definition. SGRQ CB was at least a similar if not better predictor of future exacerbations than classic CB.

Original languageEnglish (US)
Pages (from-to)685-695
Number of pages11
JournalCHEST
Volume156
Issue number4
DOIs
StatePublished - Oct 2019

Bibliographical note

Funding Information:
Financial/nonfinancial disclosures: V. K. has received personal fees from CSA Medical, AstraZeneca , Boehringer Ingelheim , and Concert Pharmaceuticals. V. K. has also received personal fees from the American Board of Internal Medicine and Gala Therapeutics. M. K. H. reports consulting for GlaxoSmithKline , Boehringer Ingelheim , and AstraZeneca . She has received research support from Novartis and Sunovion . B. J. M. reports funding from the NHLBI for the COPDGene study; grants and medical advisory boards from Boehringer Ingelheim , GlaxoSmithKline , AstraZeneca , and Sunovion; personal fees for DSMB from Spiration and Shire /Baxalta; CME personal fees from WebMD, National Jewish Health , the American College of Chest Physicians, Projects in Knowledge, Hybrid Communications, SPIRE Learning, Ultimate Medical Academy, Catamount Medical, Eastern Pulmonary Society, Catamount Medical Communications Medscape, Eastern VA Medical Center, Academy for Continued Healthcare Learning, and Mt. Sinai Medical Center; royalties from Up-To-Date; medical advisory boards from Novartis , Phillips, Third Pole, Science 24/7, and Vernoa; grants from Pearl; outside the submitted work. J. L. C. reports a grant from NHLBI directly related to this study, and grants from NIAID , NHLBI , the Department of Veterans Affairs , Department of Defense , and MedImmune Corp. Ltd, outside the scope of this study. E. K. S. received honoraria from Novartis for Continuing Medical Education Seminars and grant and travel support from GlaxoSmithKline. G. J. C. has received grants from the US NIH and the Department of Defense, consulting from AstraZeneca, Boehringer Ingelheim, Holaira, Mereo, Third Pole, PneumRx, Pulmonx, Pearl, Amirall, CSA Medical, Broncus, AVISA, Lungpacer, and GlaxoSmithKline; and contracted clinical trials from AstraZeneca, Avisa, Mereo, Boehringer Ingelheim, Broncus, GlaxoSmithKline, Lungpacer, Novartis, Pulmonx, PneumRx/BTG, and Yungjin. None declared (H. Z., E. R., J. D. C., P. W. J.).

Funding Information:
FUNDING/SUPPORT: The project described was supported by the National Heart, Lung, and Blood Institute [Awards U01 HL089897 and U01 HL089856]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Heart, Lung, and Blood Institute or the National Institutes of Health. COPD Foundation Funding: The COPDGene study (NCT00608764) is also supported by the COPD Foundation through contributions made to an Industry Advisory Committee composed of AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, and Sunovion.Author contributions: V. K. conceived and designed the analysis plan, performed data analysis, and contributed significantly to the writing of the manuscript. H. Z. performed the data analysis and designed the analysis plan. E. R. acquired data used in the manuscript and contributed to the data analysis. M. K. H. contributed to the data analysis and writing of the manuscript. B. J. M. contributed to the writing of the manuscript. J. D. C. P. W. J. J. L. C. and G. J. C. contributed to the conception of the analysis plan and writing of the manuscript. E. K. S. contributed to the data analysis and the writing of the manuscript. Financial/nonfinancial disclosures: V. K. has received personal fees from CSA Medical, AstraZeneca, Boehringer Ingelheim, and Concert Pharmaceuticals. V. K. has also received personal fees from the American Board of Internal Medicine and Gala Therapeutics. M. K. H. reports consulting for GlaxoSmithKline, Boehringer Ingelheim, and AstraZeneca. She has received research support from Novartis and Sunovion. B. J. M. reports funding from the NHLBI for the COPDGene study; grants and medical advisory boards from Boehringer Ingelheim, GlaxoSmithKline, AstraZeneca, and Sunovion; personal fees for DSMB from Spiration and Shire/Baxalta; CME personal fees from WebMD, National Jewish Health, the American College of Chest Physicians, Projects in Knowledge, Hybrid Communications, SPIRE Learning, Ultimate Medical Academy, Catamount Medical, Eastern Pulmonary Society, Catamount Medical Communications Medscape, Eastern VA Medical Center, Academy for Continued Healthcare Learning, and Mt. Sinai Medical Center; royalties from Up-To-Date; medical advisory boards from Novartis, Phillips, Third Pole, Science 24/7, and Vernoa; grants from Pearl; outside the submitted work. J. L. C. reports a grant from NHLBI directly related to this study, and grants from NIAID, NHLBI, the Department of Veterans Affairs, Department of Defense, and MedImmune Corp. Ltd, outside the scope of this study. E. K. S. received honoraria from Novartis for Continuing Medical Education Seminars and grant and travel support from GlaxoSmithKline. G. J. C. has received grants from the US NIH and the Department of Defense, consulting from AstraZeneca, Boehringer Ingelheim, Holaira, Mereo, Third Pole, PneumRx, Pulmonx, Pearl, Amirall, CSA Medical, Broncus, AVISA, Lungpacer, and GlaxoSmithKline; and contracted clinical trials from AstraZeneca, Avisa, Mereo, Boehringer Ingelheim, Broncus, GlaxoSmithKline, Lungpacer, Novartis, Pulmonx, PneumRx/BTG, and Yungjin. None declared (H. Z. E. R. J. D. C. P. W. J.). Role of sponsors: The sponsor had no role in the design of the study, the collection and analysis of the data, or the preparation of the manuscript. *COPDGene Investigators Collaborators—Core Units: Administrative Center: James D. Crapo, MD (PI); Edwin K. Silverman, MD, PhD (PI); Barry J. Make, MD; Elizabeth A. Regan, MD, PhD. Genetic Analysis Center: Terri Beaty, PhD; Ferdouse Begum, PhD; Robert Busch, MD; Peter J. Castaldi, MD, MSc; Michael Cho, MD; Dawn L. DeMeo, MD, MPH; Adel R. Boueiz, MD; Marilyn G. Foreman, MD, MS; Eitan Halper-Stromberg; Nadia N. Hansel, MD, MPH; Megan E. Hardin, MD; Lystra P. Hayden, MD, MMSc; Craig P. Hersh, MD, MPH; Jacqueline Hetmanski, MS, MPH; Brian D. Hobbs, MD; John E. Hokanson, MPH, PhD; Nan Laird, PhD; Christoph Lange, PhD; Sharon M. Lutz, PhD; Merry-Lynn McDonald, PhD; Margaret M. Parker, PhD; Dandi Qiao, PhD; Elizabeth A. Regan, MD, PhD; Stephanie Santorico, PhD; Edwin K. Silverman, MD, PhD; Emily S. Wan, MD; Sungho Won. Imaging Center: Jean-Paul Charbonnier; Harvey O. Coxson, PhD; MeiLan K. Han, MD, MS; Eric A. Hoffman, PhD; Stephen Humphries, PhD; Francine L. Jacobson, MD, MPH; Philip F. Judy, PhD; Ella A. Kazerooni, MD; Alex Kluiber; David A. Lynch, MB; John D. Newell, Jr. MD; Elizabeth A. Regan, MD, PhD; James C. Ross, PhD; Raul San Jose Estepar, PhD; Jered Sieren; Berend C. Stoel, PhD; Juerg Tschirren, PhD; Edwin Van Beek, MD, PhD; Bram van Ginneken, PhD; Eva van Rikxoort, PhD; George Washko, MD; Carla G. Wilson, MS. PFT QA Center, Salt Lake City, UT: Robert Jensen, PhD. Data Coordinating Center and Biostatistics, National Jewish Health, Denver, CO: Douglas Everett, PhD; Jim Crooks, PhD; Camille Moore, PhD; Matt Strand, PhD; Carla G. Wilson, MS. Epidemiology Core, University of Colorado Anschutz Medical Campus, Aurora, CO: John E. Hokanson, MPH, PhD; John Hughes, PhD; Gregory Kinney, MPH, PhD; Sharon M. Lutz, PhD; Katherine Pratte, MSPH; Kendra A. Young, PhD. Clinical Centers: Ann Arbor VA, Ann Arbor, MI: Jeffrey L. Curtis, MD; Carlos H. Martinez, MD, MPH; Perry G. Pernicano, MD. Baylor College of Medicine, Houston, TX: Nicola Hanania, MD, MS; Philip Alapat, MD; Mustafa Atik, MD; Venkata Bandi, MD; Aladin Boriek, PhD; Kalpatha Guntupalli, MD; Elizabeth Guy, MD; Arun Nachiappan, MD; Amit Parulekar, MD. Brigham and Women's Hospital, Boston, MA: Dawn L. DeMeo, MD, MPH; Craig Hersh, MD, MPH; Francine L. Jacobson, MD, MPH; George Washko, MD. Columbia University, New York, NY: R. Graham Barr, MD, DrPH; John Austin, MD; Belinda D'Souza, MD; Gregory D. N. Pearson, MD; Anna Rozenshtein, MD, MPH, FACR; Byron Thomashow, MD. Duke University Medical Center, Durham, NC: Neil MacIntyre, Jr. MD; H. Page McAdams, MD; Lacey Washington, MD. HealthPartners Research Institute, Minneapolis, MN: Charlene McEvoy, MD, MPH; Joseph Tashjian, MD. Johns Hopkins University, Baltimore, MD: Robert Wise, MD; Robert Brown, MD; Nadia N. Hansel, MD, MPH; Karen Horton, MD; Allison Lambert, MD, MHS; Nirupama Putcha, MD, MHS. Los Angeles Biomedical Research Institute at Harbor UCLA Medical Center, Torrance, CA: Richard Casaburi, PhD, MD; Alessandra Adami, PhD; Matthew Budoff, MD; Hans Fischer, MD; Janos Porszasz, MD, PhD; Harry Rossiter, PhD; William Stringer, MD. Michael E. DeBakey VAMC, Houston, TX: Amir Sharafkhaneh, MD, PhD; Charlie Lan, DO. Minneapolis VA, Minneapolis, MN: Christine Wendt, MD; Brian Bell, MD. Morehouse School of Medicine, Atlanta, GA: Marilyn G. Foreman, MD, MS; Eugene Berkowitz, MD, PhD; Eric L. Flenaugh, MD; Gloria Westney, MD, MS. National Jewish Health, Denver, CO: Russell Bowler, MD, PhD; David A. Lynch, MB. Reliant Medical Group, Worcester, MA: Richard Rosiello, MD; David Pace, MD. Temple University, Philadelphia, PA: Gerard Criner, MD; David Ciccolella, MD; Francis Cordova, MD; Chandra Dass, MD; Gilbert D'Alonzo, DO; Parag Desai, MD; Michael Jacobs, PharmD; Steven Kelsen, MD, PhD; Victor Kim, MD; A. James Mamary, MD; Nathaniel Marchetti, DO; Aditi Satti, MD; Kartik Shenoy, MD; Robert M. Steiner, MD; Maria Elena Vega-Sanchez, MD. University of Alabama, Birmingham, AL: Mark Dransfield, MD; William Bailey, MD; Surya Bhatt, MD; Anand Iyer, MD; Hrudaya Nath, MD; Gabriela Oates, PhD; Sushil Sonavane, MD; J. Michael Wells, MD. University of California, San Diego, CA: Joe Ramsdell, MD; Paul Friedman, MD; Xavier Soler, MD, PhD; Andrew Yen, MD. University of Iowa, Iowa City, IA: Alejandro P. Comellas, MD; John Newell, Jr. MD; Brad Thompson, MD. University of Michigan, Ann Arbor, MI: MeiLan K. Han, MD, MS; Ella Kazerooni, MD; Carlos H. Martinez, MD, MPH. University of Minnesota, Minneapolis, MN: Joanne Billings, MD; Abbie Begnaud, MD; Tadashi Allen, MD. University of Pittsburgh, Pittsburgh, PA: Frank Sciurba, MD; Jessica Bon, MD; Divay Chandra, MD, MSc; Carl Fuhrman, MD; Joel Weissfeld, MD, MPH. University of Texas Health Science Center at San Antonio, San Antonio, TX: Antonio Anzueto, MD; Sandra Adams, MD; Diego Maselli-Caceres, MD; Mario E. Ruiz, MD. FUNDING/SUPPORT: The project described was supported by the National Heart, Lung, and Blood Institute [Awards U01 HL089897 and U01 HL089856]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Heart, Lung, and Blood Institute or the National Institutes of Health. COPD Foundation Funding: The COPDGene study (NCT00608764) is also supported by the COPD Foundation through contributions made to an Industry Advisory Committee composed of AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, and Sunovion.

Funding Information:
FUNDING/SUPPORT: The project described was supported by the National Heart, Lung, and Blood Institute [Awards U01 HL089897 and U01 HL089856]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Heart, Lung, and Blood Institute or the National Institutes of Health. COPD Foundation Funding: The COPDGene study (NCT00608764) is also supported by the COPD Foundation through contributions made to an Industry Advisory Committee composed of AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, and Sunovion.Author contributions: V. K. conceived and designed the analysis plan, performed data analysis, and contributed significantly to the writing of the manuscript. H. Z. performed the data analysis and designed the analysis plan. E. R. acquired data used in the manuscript and contributed to the data analysis. M. K. H. contributed to the data analysis and writing of the manuscript. B. J. M. contributed to the writing of the manuscript. J. D. C. P. W. J. J. L. C. and G. J. C. contributed to the conception of the analysis plan and writing of the manuscript. E. K. S. contributed to the data analysis and the writing of the manuscript. Financial/nonfinancial disclosures: V. K. has received personal fees from CSA Medical, AstraZeneca, Boehringer Ingelheim, and Concert Pharmaceuticals. V. K. has also received personal fees from the American Board of Internal Medicine and Gala Therapeutics. M. K. H. reports consulting for GlaxoSmithKline, Boehringer Ingelheim, and AstraZeneca. She has received research support from Novartis and Sunovion. B. J. M. reports funding from the NHLBI for the COPDGene study; grants and medical advisory boards from Boehringer Ingelheim, GlaxoSmithKline, AstraZeneca, and Sunovion; personal fees for DSMB from Spiration and Shire/Baxalta; CME personal fees from WebMD, National Jewish Health, the American College of Chest Physicians, Projects in Knowledge, Hybrid Communications, SPIRE Learning, Ultimate Medical Academy, Catamount Medical, Eastern Pulmonary Society, Catamount Medical Communications Medscape, Eastern VA Medical Center, Academy for Continued Healthcare Learning, and Mt. Sinai Medical Center; royalties from Up-To-Date; medical advisory boards from Novartis, Phillips, Third Pole, Science 24/7, and Vernoa; grants from Pearl; outside the submitted work. J. L. C. reports a grant from NHLBI directly related to this study, and grants from NIAID, NHLBI, the Department of Veterans Affairs, Department of Defense, and MedImmune Corp. Ltd, outside the scope of this study. E. K. S. received honoraria from Novartis for Continuing Medical Education Seminars and grant and travel support from GlaxoSmithKline. G. J. C. has received grants from the US NIH and the Department of Defense, consulting from AstraZeneca, Boehringer Ingelheim, Holaira, Mereo, Third Pole, PneumRx, Pulmonx, Pearl, Amirall, CSA Medical, Broncus, AVISA, Lungpacer, and GlaxoSmithKline; and contracted clinical trials from AstraZeneca, Avisa, Mereo, Boehringer Ingelheim, Broncus, GlaxoSmithKline, Lungpacer, Novartis, Pulmonx, PneumRx/BTG, and Yungjin. None declared (H. Z. E. R. J. D. C. P. W. J.). Role of sponsors: The sponsor had no role in the design of the study, the collection and analysis of the data, or the preparation of the manuscript. *COPDGene Investigators Collaborators?Core Units: Administrative Center: James D. Crapo, MD (PI); Edwin K. Silverman, MD, PhD (PI); Barry J. Make, MD; Elizabeth A. Regan, MD, PhD. Genetic Analysis Center: Terri Beaty, PhD; Ferdouse Begum, PhD; Robert Busch, MD; Peter J. Castaldi, MD, MSc; Michael Cho, MD; Dawn L. DeMeo, MD, MPH; Adel R. Boueiz, MD; Marilyn G. Foreman, MD, MS; Eitan Halper-Stromberg; Nadia N. Hansel, MD, MPH; Megan E. Hardin, MD; Lystra P. Hayden, MD, MMSc; Craig P. Hersh, MD, MPH; Jacqueline Hetmanski, MS, MPH; Brian D. Hobbs, MD; John E. Hokanson, MPH, PhD; Nan Laird, PhD; Christoph Lange, PhD; Sharon M. Lutz, PhD; Merry-Lynn McDonald, PhD; Margaret M. Parker, PhD; Dandi Qiao, PhD; Elizabeth A. Regan, MD, PhD; Stephanie Santorico, PhD; Edwin K. Silverman, MD, PhD; Emily S. Wan, MD; Sungho Won. Imaging Center: Jean-Paul Charbonnier; Harvey O. Coxson, PhD; MeiLan K. Han, MD, MS; Eric A. Hoffman, PhD; Stephen Humphries, PhD; Francine L. Jacobson, MD, MPH; Philip F. Judy, PhD; Ella A. Kazerooni, MD; Alex Kluiber; David A. Lynch, MB; John D. Newell, Jr. MD; Elizabeth A. Regan, MD, PhD; James C. Ross, PhD; Raul San Jose Estepar, PhD; Jered Sieren; Berend C. Stoel, PhD; Juerg Tschirren, PhD; Edwin Van Beek, MD, PhD; Bram van Ginneken, PhD; Eva van Rikxoort, PhD; George Washko, MD; Carla G. Wilson, MS. PFT QA Center, Salt Lake City, UT: Robert Jensen, PhD. Data Coordinating Center and Biostatistics, National Jewish Health, Denver, CO: Douglas Everett, PhD; Jim Crooks, PhD; Camille Moore, PhD; Matt Strand, PhD; Carla G. Wilson, MS. Epidemiology Core, University of Colorado Anschutz Medical Campus, Aurora, CO: John E. Hokanson, MPH, PhD; John Hughes, PhD; Gregory Kinney, MPH, PhD; Sharon M. Lutz, PhD; Katherine Pratte, MSPH; Kendra A. Young, PhD. Clinical Centers: Ann Arbor VA, Ann Arbor, MI: Jeffrey L. Curtis, MD; Carlos H. Martinez, MD, MPH; Perry G. Pernicano, MD. Baylor College of Medicine, Houston, TX: Nicola Hanania, MD, MS; Philip Alapat, MD; Mustafa Atik, MD; Venkata Bandi, MD; Aladin Boriek, PhD; Kalpatha Guntupalli, MD; Elizabeth Guy, MD; Arun Nachiappan, MD; Amit Parulekar, MD. Brigham and Women's Hospital, Boston, MA: Dawn L. DeMeo, MD, MPH; Craig Hersh, MD, MPH; Francine L. Jacobson, MD, MPH; George Washko, MD. Columbia University, New York, NY: R. Graham Barr, MD, DrPH; John Austin, MD; Belinda D'Souza, MD; Gregory D. N. Pearson, MD; Anna Rozenshtein, MD, MPH, FACR; Byron Thomashow, MD. Duke University Medical Center, Durham, NC: Neil MacIntyre, Jr. MD; H. Page McAdams, MD; Lacey Washington, MD. HealthPartners Research Institute, Minneapolis, MN: Charlene McEvoy, MD, MPH; Joseph Tashjian, MD. Johns Hopkins University, Baltimore, MD: Robert Wise, MD; Robert Brown, MD; Nadia N. Hansel, MD, MPH; Karen Horton, MD; Allison Lambert, MD, MHS; Nirupama Putcha, MD, MHS. Los Angeles Biomedical Research Institute at Harbor UCLA Medical Center, Torrance, CA: Richard Casaburi, PhD, MD; Alessandra Adami, PhD; Matthew Budoff, MD; Hans Fischer, MD; Janos Porszasz, MD, PhD; Harry Rossiter, PhD; William Stringer, MD. Michael E. DeBakey VAMC, Houston, TX: Amir Sharafkhaneh, MD, PhD; Charlie Lan, DO. Minneapolis VA, Minneapolis, MN: Christine Wendt, MD; Brian Bell, MD. Morehouse School of Medicine, Atlanta, GA: Marilyn G. Foreman, MD, MS; Eugene Berkowitz, MD, PhD; Eric L. Flenaugh, MD; Gloria Westney, MD, MS. National Jewish Health, Denver, CO: Russell Bowler, MD, PhD; David A. Lynch, MB. Reliant Medical Group, Worcester, MA: Richard Rosiello, MD; David Pace, MD. Temple University, Philadelphia, PA: Gerard Criner, MD; David Ciccolella, MD; Francis Cordova, MD; Chandra Dass, MD; Gilbert D'Alonzo, DO; Parag Desai, MD; Michael Jacobs, PharmD; Steven Kelsen, MD, PhD; Victor Kim, MD; A. James Mamary, MD; Nathaniel Marchetti, DO; Aditi Satti, MD; Kartik Shenoy, MD; Robert M. Steiner, MD; Maria Elena Vega-Sanchez, MD. University of Alabama, Birmingham, AL: Mark Dransfield, MD; William Bailey, MD; Surya Bhatt, MD; Anand Iyer, MD; Hrudaya Nath, MD; Gabriela Oates, PhD; Sushil Sonavane, MD; J. Michael Wells, MD. University of California, San Diego, CA: Joe Ramsdell, MD; Paul Friedman, MD; Xavier Soler, MD, PhD; Andrew Yen, MD. University of Iowa, Iowa City, IA: Alejandro P. Comellas, MD; John Newell, Jr. MD; Brad Thompson, MD. University of Michigan, Ann Arbor, MI: MeiLan K. Han, MD, MS; Ella Kazerooni, MD; Carlos H. Martinez, MD, MPH. University of Minnesota, Minneapolis, MN: Joanne Billings, MD; Abbie Begnaud, MD; Tadashi Allen, MD. University of Pittsburgh, Pittsburgh, PA: Frank Sciurba, MD; Jessica Bon, MD; Divay Chandra, MD, MSc; Carl Fuhrman, MD; Joel Weissfeld, MD, MPH. University of Texas Health Science Center at San Antonio, San Antonio, TX: Antonio Anzueto, MD; Sandra Adams, MD; Diego Maselli-Caceres, MD; Mario E. Ruiz, MD.

Publisher Copyright:
© 2019 American College of Chest Physicians

Keywords

  • COPD
  • chronic bronchitis
  • cough
  • exacerbations

Fingerprint Dive into the research topics of 'The St. George's Respiratory Questionnaire Definition of Chronic Bronchitis May Be a Better Predictor of COPD Exacerbations Compared With the Classic Definition'. Together they form a unique fingerprint.

Cite this