Lactose after Roux-en-Y gastric bypass for morbid obesity, is it a problem?

Figures & data

Table 1. Patient characteristics.

	Preoperative (n = 84)	Postoperative (n = 84)
Age in years – mean (SD)	44.7 (11.1)	48.8 (9.9)
Female sex – n (%)	71 (84.5)	71 (84.5)
NW-E origin – n (%)	75 (89.3)	77 (91.7)
Weight in kilograms – mean (SD)	118.7 (14.6)	87.0 (19.4)
Body mass index in kg/m^2 – mean (SD)	41.1 (3.9)	29.8 (5.1)
Time postoperative in months – median (IQR)	–	36.0 (24.0-52.3)

N: number of patients; SD: Standard deviation; NW-E: Northwest European.

Figure 1. Median hydrogen (A), methane (B) and mean glucose (C) levels per time point for all pre and postoperative patients and subdivided for test outcome. PPM: parts per million; mmol/L: millimoles per litre; BL: baseline; min: minutes; LBT: lactose breath test; LTT: lactose tolerance test; neg: negative test outcome; pos: positive test outcome.

Table 2. Exact numbers and odds ratio’s for lactose malabsorption, increase in complaints during lactose test and lactose intolerance.

	Positive	Negative	Crude	Adjusted
	n (%)	n (%)	OR (95% CI, p-value)	OR (95% CI; p-value)
Lactose malabsorption
Operation status
Pre	15 (17.9)	69 (82.1)	Ref	Ref
Post	25 (29.8)	59 (70.2)	1.95 (0.94–4.04; 0.07)	2.46 (1.08–5.59; 0.03)
Increase in complaints
Operation status
Pre	19 (22.6)	65 (77.4)	Ref	Ref
Post	23 (27.4)	61 (72.6)	1.29 (0.64–2.60; 0.48)	1.22 (0.61–2.44; 0.58)
Lactose intolerance
Operation status
Pre	6 (7.1)	78 (92.9)	Ref	Ref
Post	8 (9.5)	76 (90.5)	1.37 (0.45–4.13; 0.58)	1.48 (0.48–4.57; 0.50)

Pre: preoperative; post: postoperative; n: number of patients; ref: reference; OR: odds ratio; CI: confidence interval; Adjusted OR: adjustment for country of origin.

Table 3. Lactose breath test and lactose tolerance test results.

	LTT +	LTT −
	Pre Post	Pre Post
LBT + n (%)	7 (8.3) 5 (6.0)	4 (4.8) 17 (20.2)
LBT − n (%)	4 (4.8) 3 (3.6)	69 (82.1) 59 (70.2)

LBT: lactose hydrogen breath test; LTT: lactose tolerance test; +: positive outcome; −: negative outcome; n: number of patients; Between brackets: percentage of preoperative or postoperative patients; Pre: preoperative; Post: postoperative.

Table 4. Most frequently reported complaints after dairy consumption.

	Preoperative (n = 84) (%)	Postoperative (n = 84) (%)
Bowel cramps	7.1	42.9^a
Diarrhoea	7.1	34.5^a
Nausea	2.4	33.3^a
Tiredness	1.2	31.0^a
Abdominal bloating	8.3	31.0^a

^a Significantly different from preoperative (p < .01). n: number.