Tailoring Limb length based on total small bowel length in omega-loop gastric bypass

One-anastomosis gastric bypass (OAGB) is currently one of the most effective
treatment options for morbid obesity. It is technically a more simple procedure
compared to the RYGB and has proven in some studies to have a better outcome in
terms of weight loss and reduction of co-morbidities.
The aim of the weight loss surgery is to achieve an optimum weight loss aiming
at a BMI of 25 kg/m2 in combination with a minimum of side effects, like
vitamin, macronutrient, mineral deficiencies and diarhea.
There is substantial variation in the determination of the biliopancreatic (BP)
limb length of the anastomosis with some surgeons using a fixed length and some
a length based on the initial BMI. The length varies between less than 150 cm
to more than 250 cm. A recent retrospective study by Charalampos et.al.
adjusting limb length from 200 to 300 cm depending on BMI resulted in on
average comparable EWL when corrected for initial BMI. The average BMI after 36
months was 27.5 Kg/m2 (± 5.3). This strategy of BP based on initial BMI results
in 16% of patients with a final BMI > 33 and 16% with less than 22.
Furthermore despite (over-the-counter) multivitamin suppletion 20% or more
patients developed de novo deficiencies of iron, vit B12, vit D, and/or
minerals in the first postoperative year (1).
Ahuja et.al. adjusted the limb length from 150 to 250 cm depending on BMI and
also found increasing number of deficiences of micro-nutrients with increasing
BP length (2). In this study patients were advised to use a multivitamin
supplement, however no specific brand was used.
In RYGB surgery there is some evidence for a role of length of the BP limb on
weight loss. Nergaard et al. performed a RCT comparing a BP limb of 200 to 60
cm with a alimentary limb of 60 and 150 cm respectively. The longer limb length
led to more weight loss but also to more bowel movements and micronutrient
deficiencies (3). Total small bowel length was measured in their whole patient
population and varied between 480 and 870 cm but was not taken in to account in
terms of stratification.
Zorilla et.al performed a systematic review on limb length in RYGB and found 13
studies meeting adequate quality (4). Weight loss on the whole was better in
patients with longer BP limbs.
There is evidence in the RYGB literature that the length of the common channel
plays a role in the outcome of surgery both in weight loss and in micronutrient
deficiencies. It is known that the length of the total small bowel can vary
considerably with measured values between 350 to more than 1000 cm (5).
In this study in 443 patients TSB median length was 690 cm (women 678±92, men
728±85 cm) with a SD of 94 cm. In males 3% had a bowel length < 400 cm and 15%
> 800, in females 2% had a length of < 400 cm and 5% > 800 cm.
In current practice in OAGB surgery surgeons use a fixed BP-limb length or
adjust the length to the initial BMI. Total weight loss varies in literature
between 30-35 % with SD up to 8.5%, aiming at a BMI result between 23 and 30
Kg/m2
The contribution of the length of the residual small bowel, total minus the
BP-limb, on weight loss and deficiencies has up till now not been studied in
OAGB surgery

To investigate whether adjusting the length of the BP-limb of the OAGB based
on measured total small bowel length leads to more weight loss, resolution of
co-morbidities with less development of micronutrient deficiencies and bowel
movements compared a to standard limb length in OAGB in patients using a
standardized multivitamin supplement (FitForMe Primo).

Primary Objective:
To compare the percent total weight loss (%TWL) at 5 years between the group
with the standard BP-length and the group with a adjusted BP-length .

Secondary Objective(s):
1) To compare the percent of total weight loss (%TWL) between the groups at
1,2,3 and 4 years.

2) To compare the percent excess weight loss (%EWL) between the groups at
1,2,3, 4 and 5 years.
Definition: %EWL (Initial Weight - Postop Weight) / (Initial Weight -
Ideal Weight)
(ideal weight is defined by the weight corresponding to a BMI of 25
kg/m2 )

3) To compare the percent excess BMI loss (%EBMIL) between the groups at 1,2,
3, 4 and 5 years.
Definition: %EBMIL (ΔBMI / (Initial BMI - 25)) * 100)

4) To compare the proportion of patients with 22 <= BMI <= 30 between the
groups at 1,2 3, 4 and 5 years.

5) To compare the mean number of daily bowel movements and number of days with
daily bowel movements > 3 over in the last two weeks at 6 months, between the
groups at 1,2, 3, 4, and 5 years.

6) To compare the Quality of life measured by the RAND-36 questionnaire between
the groups at 6 months, 1,2, 3, 4 and 5 years

7) To compare the percentage of patients experiencing moderate to severe
dumping symptoms defined by the Dumping Severity Score (DSS) (see Emous
et.al.) at 6 months, year 1, 2, 3, 4 and 5 between the groups.

8) To compare the proportion of patients in the two groups who have neither
deficiencies of iron, nor vit. D, nor vit B12 without extra suppletion, at 6
months, 1, 2, 3, 4 and 5 years. Deficiencies are defined by the lower border of
the local normal laboratory values.

9) To compare the proportion of patients in the two groups who have a
deficiency at 6 months, 1, 2, 3, 4 and 5 years, or received extra suppletion
for :
- Vitamin B1
- Vitamin B6
- Folic acid
- Vitamin A
- Vitamin D
- Calcium
- Phosphate
- Albumin
- Zinc
- Copper
- Selenium
Deficiencies are defined by the lower border of the local normal laboratory
values.

10)To compare the proportion of patients between the groups at 1, 2, 3, 4 and 5
years without diabetes, both those with remission of diabetes and those without
de novo diabetes, defined as an HbA1c less than 48 mmol/mol without diabetes
medication in the last 6 months.
11) To compare the proportion of patients between the groups at 1, 2, 3,4 and 5
years with improvement of diabetes, defined as a reduction of HbA1c with at
least 10 mmol/mol, but not reaching remission criteria and/or less
anti-diabetic medication.
12) To compare the proportion of patients between the groups at 1, 2, 3, 4 and
5 years with remission of hypertension, defined as a blood pressure of 140/90
mmHg or less without antihypertensive medication.
13) To compare the proportion of patients between the groups at 1, 2, 3, 4 and
5 years with improvement of hypertension, defined as a lower blood pressure of
at least 10 mm Hg systolic and/or 5 mmHg diastolic, and/or less
antihypertensive medication (not reaching the criterion of remission).
14) To compare the proportion of patients between the groups at 1, 2, 3, 4 and
5 years with resolution of sleep apnea, defined by cessation of CPAP or other
devices use, documented by their own pulmonologist
15) To perform analysis of the above parameters in the subgroups with TSBL
500-700 and >700.
16) To compare within the standard group of patients with an allocated BP-limb
length of 150 cm those with a TSBL < 500 to those with a TSBL 500-700 and to
those with TSBL >700 cm on the above mentioned parameters.
17) to perform regression analysis on other factors possibly contributing to
the primary or secondary outcomes.

This is a double-blind randomized 5 year study with two arms. Patients who are
scheduled for primary OLGB surgery are eligible when during the surgery total
small bowel length can be measured and if they are able to swallow the Fitforme
WLS primo multivitamin capsule. Patients will be allocated to one of the two
surgical treatment arms by randomization at the beginning of the operation.
Only the operating surgeon is aware of the allocation and will document total
small bowel length, treatment allocation and BP-length in a coded database.
Both the TSBL and the length of the BP-limb will not be documented in the
patient file. The investigators and the patient will not be informed on the
BP-limb length during the study.
Patients with a TSBL of less than 500 cm will recieve the same treatment
whether they are allocated to the standard arm or to the alternative arm. For
logistic reasons they will also be randomized and those with the experimental
arm will be combined with the standard group for the analysis. Based on
literature the percentage patients with a TSBL < 500 cm will be probably less
than 5, not causing statistical issues (5).
Patients with a small bowel that could not be measured during surgery will be
treated according to the current daily practice and will not enter the study.

Patients will be randomly allocated to one of the two treatment arms :
- 1. A standard BP-limb length of 150 cm
- 2. A BP-limb length depending on total small bowel length (TSBL) measured
during the surgical procedure :
- TSBL : < 500 cm : 150 cm
- TSBL : 500-700 cm : 180 cm
- TSBL : > 700 cm : 210 cm

burden and risks :
1. a full measurement of the small bowel length during surgery includes a
small risk of laceration of the bowel. The surgeons are experienced in this
technique of measuring as they need to measure the distance from Treitz to the
planned anastomosis during the standard procedure of the OAGB.
2. the adjusted lengths of the biliopancreatic limb based on total small bowel
length are within the currently used lengths in literature and are considered
safe. Whether this leads to less or more adverse events in the patients after
the surgery is part of the investigation. However, all expected side effects
are treatable.


Potential benefits are a better outcome of weight reduction compared to current
usual care without increases in vitamin and/or micronutrient deficiencies.