Table 1

Examples of definitions of heartburn severity used in clinical trials

	Definition	Comment	Studies where definition was used
Four grade modified Likert scale	None: no heartburn	Most intense episode of heartburn during the previous 24 hours rated by patient diaries	Castell¹³
	Mild: awareness of heartburn, but easily tolerated
	Moderate: discomforting heartburn sufficient to cause interference with normal activities, including sleep	Most intense episode of heartburn during the previous 7 days rated by the investigator	Johnson¹⁴
	Severe: incapacitating heartburn, with inability to perform normal activities, including sleep
Four grade modified Likert scale	None	Overall heartburn intensity over each 24 hour period rated by patient diaries	Johnsson⁴³
	Mild: awareness of symptom but easily tolerated
	Moderate: discomfort sufficient to cause interference with normal activities	Overall heartburn symptoms in the previous 7 days	Bate⁴⁴
	Severe: incapacitating, with inability to perform normal activities
Five grade modified Likert scale	None		Schwizer³²
	Mild: rare symptoms, no medication needed
	Moderate: not interfering with daily activities, medications used occasionally, no dietary restriction
	Severe: interfering with daily activities, chronic medications, dietary restrictions
	Very severe: incapacitating, preventing daily activities, partial relief on medication, weight loss
Seven grade modified Likert scale	None, minor, mild, moderate, quite severe, severe, very severe		Brun⁴⁵
Visual analogue scale	0–100 mm scale ranging from no symptoms to unbearable symptoms		Faaij⁴⁰