Validation of the IPF-specific version of St. George's Respiratory Questionnaire

Respir Res. 2019 Aug 28;20(1):199. doi: 10.1186/s12931-019-1169-9.

Abstract

Background: Patients with idiopathic pulmonary fibrosis (IPF) have impaired health-related quality of life (HRQL). To measure HRQL, an IPF-specific version of the St. George's Respiratory Questionnaire (SGRQ-I) was developed, but not sufficiently validated. This study aimed to assess the validity (i.a. known-groups validity and concurrent validity) and test-retest reliability of SGRQ-I in IPF patients with different disease durations.

Methods: Patients with IPF were consecutively recruited and completed SGRQ, SGRQ-I, King's Brief Interstitial Lung Disease questionnaire (K-BILD), University of California, San Diego Shortness of Breath Questionnaire (SOBQ) and Short Form-36 (SF-36) along with pulmonary function tests and a 6-min walk test (6MWT) at baseline. After two weeks, SGRQ-I and Global Rating of Change Scales (GRCS) were completed.

Results: At baseline and after two weeks, 150 and 134 patients completed the questionnaires, respectively. The internal consistency of SGRQ-I was high (Cronbach's α = 0.92). Good concurrent validity was demonstrated by high intraclass correlation coefficients (ICC = 0.97), Bland-Altman plots and moderate to strong correlations to K-BILD, SOBQ and SF-36 (r = - 0.46 to 0.80). High ICC (0.92) and a Bland-Altman plot indicated good test-retest reliability. SGRQ-I was good at discriminating between patients with different stages of disease (Δscore > 18.1, effect sizes > 0.10). Validity was similar across groups of different disease duration.

Conclusions: SGRQ-I proved to be valid at distinguishing between different disease severities, valid compared to other HRQL instruments, applicable across different disease durations and reliable upon repetition. SGRQ-I is a valid option for measuring HRQL in patients with IPF.

Trial registration: The study was registered at clinicaltrials.org ( NCT02818712 ) on 15 June 2016.

Keywords: Health-related quality of life; IPF-specific version of the St. George’s respiratory questionnaire; Idiopathic pulmonary fibrosis; Interstitial lung disease; K-BILD; Quality of life; SGRQ; SGRQ-I.

Publication types

  • Multicenter Study
  • Validation Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Cohort Studies
  • Denmark / epidemiology
  • Female
  • Humans
  • Idiopathic Pulmonary Fibrosis / diagnosis*
  • Idiopathic Pulmonary Fibrosis / epidemiology*
  • Idiopathic Pulmonary Fibrosis / psychology
  • Male
  • Quality of Life* / psychology
  • Surveys and Questionnaires / standards*
  • Translating*

Associated data

  • ClinicalTrials.gov/NCT02818712