Introduction

The Patient Global Impression of Severity (PGI-S) is a single item categorical scale used as an outcome measure in clinical trials in chronic cough (CC); however, little is known about its repeatability and responsiveness.

Methods

Consecutive patients with CC completed PGI-S (0=no cough, 1=minimal, 2=mild, 3=moderate, 4=severe, and 5=very severe cough) at 2 clinic visits. Repeatability was assessed in patients with no change in symptoms, and stability in cough severity visual analogue scale (VAS) scores (difference <20mm) over two clinic visits. Responsiveness was assessed in patients who received treatment and a fall in VAS scores (?20mm).

Results

94 participants completed the PGI-S; median (IQR) age 56 (46-67) years, 69 (73%) female, cough duration 60 (24-135) months, interval between visits 144 (84-191) days. Cough was stable in 77 participants; median (IQR) PGI-S at both visits 4 (3-4) (p=0.16), intraclass correlation (95% CI) 0.85 (0.77-0.91) (Figure 1a). PGI-S was significantly different between visits in those with improved cough (n=17); median (IQR) PGI-S 4 (3-4) vs 2 (2-3) respectively (p<0.01) and effect size 0.84 (Figure 1b).

Conclusion

The PGI-S is a repeatable and responsive outcome measure, and is instinctive and easy to use. Further studies should investigate the clinically meaningful threshold of change of PGI-S in CC.