Table 2 Univariate comparison of pH and Bilitec measurements in gastro-oesophageal reflux disease patients with and without oesophagitis (excluding Barrett’s oesophagus)

	No oesophagitis	Grade A–D	p Value
Number	228	164
Age	47.4 (1.0)	45.7 (1.1)	NS
BMI	24.4 (0.3	25.8 (0.4)	<0.001
Smoking (%)	20%	29%	<0.05
Alcohol use (%)	28%	28%	NS
Helicobacter positive (%)	25.3%	11.5%	<0.001
Hiatus hernia	23%	53%	<0.001
LOS pressure	18.5 (0.6)	15.8 (0.6)	<0.001
Normal peristalsis	89%	83%	NS
Total time acid reflux
No. of reflux episodes	36 (12–63.2)	58 (22–104)	<0.001
No. of reflux episodes >5 min	0 (0–2)	2 (0–4)	<0.001
% pH<4	1.7 (0.4–5.1)	3.8 (1–8.7)	<0.001
Upright position acid reflux
No. of reflux episodes	28.5 (9–56.3)	41 (15–85)	0.005
No. of reflux episodes >5 min	0 (0–1)	0 (0–2)	<0.05
% pH<4	1.9 (0.5–6.0)	3.6 (0.9–9.1)	<0.005
Supine position acid reflux
No. of reflux episodes	2 (0–9.5)	6 (0–24)	<0.001
Total reflux episodes >5 min	0 (0; 0)	0 (0–2)	<0.001
% pH<4	0.1 (0–1.6)	1.1 (0–9.8)	<0.001
Total time DGOR
No, of reflux episodes	11 (2–29)	22 (7–48)	<0.001
Total reflux episodes >5 min	1 (0–4)	3 (1–7)	<0.001
% bile absorbance >0.14	2.8 (0.3–12.4)	8.8 (2–25.8)	<0.001
Upright position DGOR
No. of reflux episodes	9.5 (2–25)	15 (5–33)	0.001
Total reflux episodes >5 min	1 (0–3)	2 (1–5)	<0.001
% bile absorbance >0.14	3.7 (0.4–13.6)	9.4 (1.7–27.8)	<0.001
Supine position DGOR
No. of reflux episodes	0 (0–2)	1 (0–13)	<0.001
Total reflux episodes >5 min	0 (0–1)	0 (0–3)	<0.001
% bile absorbance >0.14	0 (0–5.7)	1.2 (0–26)	<0.001

The periods are subdivided into total time, upright and supine position. The values are given in means (SD) or mean (IQR) and compared with the Mann–Whitney test or χ² test.
BMI, body mass index; DGOR, duodeno-gastro-oesophageal reflux; LOS, lower oesophageal sphincter.