Table 2 The associations between body mass index and waist circumference as categorical variables and several parameters of oesophageal acid exposure recorded at the distal probe (n = 204, two outliers excluded).

	BMI 25–29.9 kg/m2			BMI ⩾30 kg/m2			Waist circumference, medium tertile			Waist circumference, high tertile
	PE*	SE	p Value	PE*	SE	p Value	PE*	SE	p Value	PE*	SE	p Value
Acid reflux episodes
Total	25.37	13.86	0.069	42.91	15.89	0.008	20.58	15.38	0.182	14.51	14.71	0.325
Postprandial	13.21	7.61	0.084	30.09	8.72	0.001	14.53	8.51	0.089	11.06	8.14	0.176
Upright	16.21	10.50	0.124	27.08	13.04	0.026	10.16	11.60	0.382	10.07	11.10	0.365
Supine	9.71	6.53	0.139	15.07	7.49	0.045	11.32	7.14	0.115	3.66	6.83	0.593
Long acid reflux episodes
Total	0.874	0.610	0.153	1.518	0.699	0.031	0.73	0.68	0.280	0.80	0.65	0.218
Postprandial	0.583	0.376	0.122	1.002	0.431	0.021	0.54	0.42	0.195	0.61	0.40	0.127
Upright	0.499	0.441	0.259	0.5927	0.506	0.243	0.64	0.49	0.187	0.43	0.46	0.351
Supine	0.394	0.344	0.253	0.844	0.394	0.034	0.17	0.38	0.650	0.31	0.37	0.403
Time with pH <4
Total	23.95	11.23	0.121	36.28	17.65	0.041	15.39	17.09	0.369	13.79	16.35	0.400
Postprandial	12.01	8.08	0.139	23.49	9.26	0.012	10.51	8.99	0.244	9.52	8.60	0.269
Upright	13.93	8.96	0.122	16.65	10.28	0.107	12.17	9.90	0.220	6.82	9.47	0.472
Supine	100.55	9.79	0.283	19.23	11.23	0.089	4.06	10.88	0.709	6.55	10.40	0.530
% Time with pH below <4 (%)
Total	1.81	1.15	0.117	2.71	1.44	0.041	1.24	127	0.330	1.04	1.22	0.396
Postprandial	2.94	1.81	0.106	4.47	2.08	0.032	2.23	2.01	0.268	1.58	1.92	0.411
Upright	1.67	1.10	0.107	2.29	1.28	0.070	1.53	1.21	0.208	1.05	1.16	0.364
Supine	2.74	1.75	0.110	3.23	2.01	0.109	0.80	1.94	0.682	2.41	1.86	0.197

BMI, body mass index; PE, parameter estimate.

Results of unadjusted linear regression models.

*The magnitude of change in the outcome variable (eg, total reflux episodes) in response to one unit change in the predictor variable (eg, 1 kg of weight).