Condition category
Nutritional, Metabolic, Endocrine
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Background and study aims
Since obesity (being very overweight) is a growing health problem all over the world, more and more people are having weight-loss surgery because of its proven effects on obesity and related health problems. Having an operation is never risk free, and although weight-loss surgery is relatively safe, there are certain groups of people who are more at risk for complications. Drugs reducing stomach acid are used with varying degrees of success for the purpose of reducing complications, but it’s not clear how great this effect is and who benefits from it. The purpose of this study is to identify groups of patients that are at higher risk for complications and who could benefit most from acid suppression in the stomach.

Who can participate?
Patients that had weight loss surgery (gastric bypass) in Sweden between 2009-2014 and registered in the Scandinavian Obesity Surgery Registry.

What does the study involve?
Data is taken from the Scandinavian Obesity Surgery Register (SOReg) for patients that have had first time gastric bypass surgeries from 2009 through 2014. In addition, matching socio-economic data (that is data describing a person’s age, gender and income for example) is taken from Statistics Sweden and records on proton-pump inhibition prescriptions from the National Board of Health and Welfare's Drug Registry. Analysis is then done on this data, to see whether what type of patient is least likely to develop complications after weight loss surgery.

What are the possible benefits and risks of participating?
Not provided at time of registration

Where is the study run from?
Department of Surgery and Orthopedics, Lycksele Hospital

When is the study starting and how long is it expected to run for?
October 2016 to May 2017

Who is funding the study?
1. County Council of Västerbotten (Sweden)
2. Umeå University (Sweden)

Who is the main contact?
1. Dr Jeff Wennerlund (public)
2. Professor Ulf Gunnarsson (scientific)

Trial website

Contact information



Primary contact

Dr Jeff Wennerlund


Contact details

Lycksele Hospital
Department of Surgery and Orthopedics
+46 70-438 1109



Additional contact

Prof Ulf Gunnarsson


Contact details

Department of Surgical and Perioperative Sciences
Umeå Univerisity
901 87
+46 90-7852909

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Which sub-groups of people are more prone to complications after complications after Bariatric Surgery, and does post-operative prophylaxis with proton-pump inhibition play a role? A multiregister study



Study hypothesis

Which combinations of factors predispose to complications after gastric bypass surgery? Does prophylaxis with proton-pump inhibition play a role? What differernces can be acertained from gender, age, existing co-morbidity, BMI, and socio-economic factors? The underlying hypothesis is that certain factors play a role in complications, and if/where proton-pump inhibition has a place in the clinical setting.

Ethics approval

Regional Ethics Committee of Umeå 12/1/2016. Case number 2015/367-31

Study design

Single-site observational cohort study

Primary study design


Secondary study design

Cohort study

Trial setting


Trial type


Patient information sheet

Not applicable


Morbid obesity


Patient specific gender, age, BMI, existing co-morbidities, socio-economic status, and the presence of proton-pump inhibition is to be collected and compared with the occurrence of post-operative complications in a longitudinal multi-variate study .

After collecting data from the three registers, statistical analyses will be made focusing on the outcome of post-operative complications and their severity (according to the Clavien-Dindo scale) and necessary interventions, if any. Logistic regression models will be used in multi-variate analyses to pinpoint those factors (patient specific age, gender, BMI, pre-existing health problems, occurrence of proton-pump inhibition prophylaxis, and socioeconomic factors) that are associated with higher rates of complications, both as a total rate and for each individual complication. The rate of complications are also controlled against the Drug Registry if the prophylaxis was actually retrieved, or if therapy was prescribed and retrieved for other reasons.

Intervention type



Not Applicable

Drug names

Omeprazole, esomprazole

Primary outcome measure

Identification of sub-groups according to age, gender, body mass index measured in body weight (kg)/ body length (m) squared, and pre-existing health problems at baseline that have less post-operative complications and severity thereof (according to the Clavien-Dindo scale) due to prophylaxis with proton-pump inhibition, measured at 30 days and at 1 and 2 years post-operatively.

Secondary outcome measures

Identification of socioeconomic factors at baseline that impact related health problems, the rate of post-operative complications, and occurrence and adherence to proton-pump prophylaxis.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Patients eligible and accepted for primary laparoscopic gastric bypass surgery in Sweden during 2009-2014, and registered in the Scandinavian Obesity Surgery Registry (SOReg).

Participant type


Age group




Target number of participants

ca 39,000

Total final enrolment


Participant exclusion criteria

Participants that do not fulfill inclusion criteria

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Department of Surgery and Orthopedics, Lycksele Hospital
Hedlundavägen Lycksele lasarett

Sponsor information


County Council of Västerbotten (Västerbottens läns landsting)

Sponsor details

Köksvägen 11
901 89
+46 90-785 0000

Sponsor type




Funder type


Funder name

County Council of Västerbotten (Västerbottens läns landsting)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

Umeå Universitet

Alternative name(s)

Umeå University

Funding Body Type

government organisation

Funding Body Subtype

Local government



Results and Publications

Publication and dissemination plan

The results are to be published in a peer-review scientific journal. The results will be presented within the local research network, and at national and international scientific conferences.

IPD sharing statement
Collecting data from these registers is done under certain conditions. These include that the data may not be shared with a third party, is to be used only according to the purpose stated in the applications and the signed contracts, and that the data is to be erased after the project is completed. Further the information is to be handled in the same manner as patient charts, with utmost confidentiality, with identifying information separate from the raw data and calculation files.

Intention to publish date


Participant level data

Not expected to be available

Basic results (scientific)

Publication list

2020 results in (added 21/04/2020)

Publication citations

Additional files

Editorial Notes

21/04/2020: The following changes were made to the trial record: 1. Publication reference added. 2. The total final enrolment was added. 19/11/2019: The intention to publish date was changed from 12/05/2019 to 18/01/2020. 01/11/2019: Internal review. 12/03/2019: The intention to publish date was changed from 28/02/2018 to 12/05/2019. 23/10/2017: The intention to publish date was changed from 30/04/2017 to 28/02/2018.