Patient-reported outcomes to assess the efficacy of extended-release guaifenesin for the treatment of acute respiratory tract infection symptoms

Table 7 Convergent validity: correlations between more and less conceptually related measures at Days 1, 4 and 8

	Daily Cough and Phlegm Diary – 8 items
	Symptom subscale – Day 1	Symptom subscale – Day 4	Symptom subscale – Day 8
Spontaneous symptom assessment: congestion	0.15*	0.50‡	0.64‡
Spontaneous symptom assessment: mucus	0.19†	0.42‡	0.59‡
Spontaneous symptom assessment: cough	0.20†	0.52‡	0.57‡
Patient’s End-of-Treatment Assessment	0.07	−0.17*	−0.32‡
WURSS-21 Total	0.50‡	0.68‡	0.70‡
WURSS-21 Symptom	0.44‡	0.65‡	0.69‡
WURSS-21 Function	0.45‡	0.61‡	0.61‡
Investigator’s End-of-Study Assessment	−0.04	−0.20†	−0.37‡

WURSS-21: the Wisconsin Upper Respiratory Symptom Survey. Spearman rank-order correlations: *p < 0.01, †p < 0.001, ‡p < 0.0001.

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