Table 3. Internal consistency and test-retest reliability of the Reflux Disease Questionnaire electronic Diary.

	PRO Validation Study		Dose-finding Study
Domain	Cronbach's alpha (95% CI) (n=580)	ICC (95% CI) (n=126)	Cronbach's alpha (95% CI) (n=625)	ICC (95% CI) (n=188)
Heartburn	0.94 (0.94–0.95)	0.65 (0.54–0.74)	0.93 (0.92–0.94)	0.80 (0.75–0.85)
Regurgitation	0.95 (0.94–0.96)	0.74 (0.65–0.81)	0.89 (0.88–0.91)	0.81 (0.75–0.85)
Hoarseness, cough, difficulty swallowing	0.89 (0.87–0.91)	0.85 (0.79–0.89)	0.85 (0.83–0.87)	0.85 (0.81–0.89)
Burping	NA	0.73 (0.63–0.8)	NA	0.77 (0.70–0.82)
Overall symptoms	0.96 (0.95–0.96)	0.75 (0.66–0.82)	0.93 (0.92–0.93)	0.81 (0.75–0.85)

CI, confidence interval; ICC, intraclass correlation coefficient; NA, not applicable (single item domain); PRO, patient-reported outcome.