Assessing health-related quality of life in patients with interstitial lung diseases

Abstract

Background: The R-Scale-PF was proposed to evaluate the health-related quality of life (HRQoL) in patients with idiopathic pulmonary fibrosis (IPF). We generated a German version of the R-Scale-PF (GR-Scale), representing the first translation of the questionnaire into another language and assessed HRQoL longitudinally in various interstitial lung diseases (ILDs) using the R-Scale-PF scoring system at a specialized ILD centre.

Methods: We have translated the questionnaire in accordance with the WHO translation guidelines and applied it to 80 ILD patients of our department, with follow-ups after 3-6 months, assessing its internal consistency, floor and ceiling effects, concurrent validity, known-groups validity, and its responsiveness to changes over time.

Results: At baseline, all 80 patients completed the GR-Scale. In 70 patients (87.5%), follow-up data could be obtained after 4.43 ± 1.2 months. The GR-Scale demonstrated acceptable internal consistency (Cronbach's α 0.749) and slight floor effects. Concurrent validity analysis showed weak but significant correlations with forced vital capacity (FVC; r=-0.282 p = 0.011) and diffusion capacity for carbon monoxide (DLco; r=-0.254 p = 0.025). In the follow-up analysis, moderate correlations were found with FVC (r=-0.41 p < 0.001) and DLco (r=-0.445 p < 0.001). No significant difference in the total score was found between patients with IPF (n = 10) and with non-IPF ILDs (n = 70). The GR-Scale successfully discriminated between groups of varying disease severity based on lung function parameters and the need for long-term oxygen therapy (LTOT). Furthermore, it was able to distinguish between patients showing improvement, stability or decline of lung function parameters.

Conclusion: Our prospective observational pilot study suggests that the GR-Scales is a simple and quick tool to measure HRQoL in patients with ILDs, thus providing an important additional information for the clinical assessment of ILD patients.

Trial registration: Our study was retrospectively registered in the German Clinical Trial Register (DRKS) on 02.11.2022 (DRKS-ID: DRKS00030599).

Keywords: HRQoL; Health related quality of life; ILD; IPF; Interstitial lung disease; Survey.

Fig. 1

Comparison of GR-Scale total scores between (a) forced vital capacity (FVC) % predicted (> 75%, 45–75%, < 45%); (b) diffusion capacity for carbon monoxide (DLco) % predicted (> 60%, 40–60%, < 40%); (c) long-term oxygen therapy (LTOT) (d) different ILD subtypes (non-IPF vs. IPF). Effect size: ES (reported as Cohen’s d)

Fig. 2

Comparison of the Δ GR-Scale total scores between (a) forced vital capacity (FVC) % predicted ( > + 5%, -5% to + 5%, <-5%) (b) diffusion capacity of carbon monoxide (DLco) % predicted ( > + 5%, -5% to + 5%, <-5%). Effect size: ES (reported as Cohen’s d)