Dyspnea is the most common presenting symptom in patients with acute heart failure (AHF), but is difficult to quantify as a research measure. The URGENT Dyspnea study compared 3 scales: (1) 10 cm VAS, (2) 5-point Likert, and (3) a 7-point Likert (both VAS and 5-point Likert were recorded in the upright and supine positions). However, the minimal clinically important difference (MCID) to patients has not been well established.Methods
We performed a secondary analysis from URGENT Dyspnea, an observational, multi-center study of AHF patients enrolled within 1 h of first physician assessment in the ED. Using the anchor-based method to determine the MCID, a one-category change in the 7-point Likert was used as the criterion standard (‘minimally improved or worse’). The main outcome measures were the change in visual analog scale (VAS) and 5-point Likert scale from baseline to 6-h assessment relative to a 1-category change response in the 7-point Likert scale (‘minimally worse’, ‘no change’, or ‘minimally better’).Results
Of the 776 patients enrolled, 491 had a final diagnosis of AHF with responses at both time points. A 10.5 mm (SD 1.6 mm) change in VAS was the MCID for improvement in the upright position, and 14.5 mm (SD 2.0 mm) in the supine position. However, there was no MCID for worsening, as few patients reported worse dyspnea. There was also no significant MCID for the 5-point Likert scale.Conclusion
A 10.5 mm change is the MCID for improvement in dyspnea over 6 h in ED patients with AHF.