title: The association of lung function and St. George's respiratory questionnaire with exacerbations in COPD: a systematic literature review and regression analysis.
abstract: BACKGROUND
  This study investigated the relationship between changes in lung function (as measured by forced expiratory volume in one second [FEV1]) and the St. George's Respiratory Questionnaire (SGRQ) and economically significant outcomes of exacerbations and health resource utilization, with an aim to provide insight into whether the effects of COPD treatment on lung function and health status relate to a reduced risk for exacerbations.
  
  
  METHODS
  A systematic literature review was conducted in MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials to identify randomized controlled trials of adult COPD patients published in English since 2002 in order to relate mean change in FEV1 and SGRQ total score to exacerbations and hospitalizations. These predictor/outcome pairs were analyzed using sample-size weighted regression analyses, which estimated a regression slope relating the two treatment effects, as well as a confidence interval and a test of statistical significance.
  
  
  RESULTS
  Sixty-seven trials were included in the analysis. Significant relationships were seen between: FEV1 and any exacerbation (time to first exacerbation or patients with at least one exacerbation, p = 0.001); between FEV1 and moderate-to-severe exacerbations (time to first exacerbation, patients with at least one exacerbation, or annualized rate, p = 0.045); between SGRQ score and any exacerbation (time to first exacerbation or patients with at least one exacerbation, p = 0.0002) and between SGRQ score and moderate-to-severe exacerbations (time to first exacerbation or patients with at least one exacerbation, p = 0.0279; annualized rate, p = 0.0024). Relationships between FEV1 or SGRQ score and annualized exacerbation rate for any exacerbation or hospitalized exacerbations were not significant.
  
  
  CONCLUSIONS
  The regression analysis demonstrated a significant association between improvements in FEV1 and SGRQ score and lower risk for COPD exacerbations. Even in cases of non-significant relationships, results were in the expected direction with few exceptions. The results of this analysis offer health care providers and payers a broader picture of the relationship between exacerbations and mean change in FEV1 as well as SGRQ score, and will help inform clinical and formulary-making decisions while stimulating new research questions for future prospective studies.
authors.affiliation: Evidera, 430 Bedford Street, Suite 300, 02420, Lexington, MA, USA. amber.martin@evidera.com.
authors.forename: Amber L
authors.initials: AL
authors.lastname: Martin
authors.affiliation: Novartis Pharmaceuticals Corporation, East Hanover, NJ, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Marvel
authors.affiliation: Evidera, 430 Bedford Street, Suite 300, 02420, Lexington, MA, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: Fahrbach
authors.affiliation: Evidera, 430 Bedford Street, Suite 300, 02420, Lexington, MA, USA.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Cadarette
authors.affiliation: Evidera, 430 Bedford Street, Suite 300, 02420, Lexington, MA, USA.
authors.forename: Teresa K
authors.initials: TK
authors.lastname: Wilcox
authors.affiliation: University of North Carolina School of Medicine, Chapel Hill, NC, USA.
authors.forename: James F
authors.initials: JF
authors.lastname: Donohue
mesh_terms: D001993:Bronchodilator Agents / Q000627:therapeutic use; D018450:Disease Progression; D005541:Forced Expiratory Volume; D006801:Humans; D015995:Prevalence; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology*; D011788:Quality of Life; D012044:Regression Analysis; D015203:Reproducibility of Results; D012129:Respiratory Function Tests / Q000706:statistics & numerical data*; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires
chemical_list: D001993:Bronchodilator Agents
keywords: COPD; Exacerbations; FEV1; Health resource utilization; Regression analysis; SGRQ