Differences in uni-dimensional breathlessness measures and thresholds for clinical response in a randomised controlled trial in people with chronic breathlessness: an exploratory study.

INTRODUCTION

Optimally measuring improvements in chronic breathlessness in clinical practice and research continues to evolve. The aim of this study was to consider the performance of uni-dimensional measures in .

METHODS

We report five measures of breathlessness (intensity: and in the previous 24 hours; ; and an affective component ) and two clinical thresholds over baseline on their 0-100 mm visual analogue scale (8.9 mm absolute improvement; and 15% relative improvement) collected in a multi-site, randomised, double-blind, parallel-arm, placebo-controlled trial of regular, low-dose, sustained-release morphine for people with with optimally treated underlying causes.

RESULTS

Participants (n=284) were mostly elderly men with severe, chronic breathlessness. showed improvement in people with more severe breathlessness and chronic obstructive pulmonary disease. By contrast, and generated similar patterns of response, as did and sness added little value. The two clinical thresholds showed differing patterns of significance.

DISCUSSION

Consistent with other recent work, worst breathlessness may be an important uni-dimensional outcome in evaluating chronic breathlessness clinically and in research. This study does not support a differential between unpleasantness now and breathlessness now, previously observed in laboratory-generated, acute-on-chronic breathlessness. Timeframe for recall (now or the last 24 hours) and the threshold for a clinical meaningful improvement (absolute (8.9 mm) or relative (15%)) affect assessment performance.