Postoperative Nausea, Vomiting and Pain After Bariatric Surgery - a National Registry Study (BAROSPOR)

August 27, 2026 updated by: Jakob Walldén, Umeå University

Pain and Nausea in the Post-Anaesthesia Care Unit After Bariatric Surgery: A Registry Study Linking the Swedish Perioperative Register (SPOR) and the Scandinavian Obesity Surgery Registry (SOReg)

Around 4,000-5,000 bariatric (weight-loss) operations are performed in Sweden every year. Nausea, vomiting and pain are common immediately after these operations, cause considerable suffering and increase the intensity and length of hospital care. Bariatric surgery is one of the procedures with the highest risk of postoperative nausea and vomiting (PONV): about one third of patients experience PONV already in the recovery unit, and registry data indicate that around 40% report severe pain at the same stage.

This study links two national quality registries - the Swedish Perioperative Register (SPOR) and the Scandinavian Obesity Surgery Registry (SOReg) - to describe how often adult patients experience nausea, vomiting and pain in the post-anaesthesia care unit after primary bariatric surgery, and to identify patient, anaesthetic and surgical factors associated with these outcomes. The study tests whether total intravenous anaesthesia, the addition of a regional nerve block, and preoperative health-related quality of life are associated with PONV and pain, and whether early PONV or pain is associated with complications, unplanned hospital care or reoperation up to one year after surgery. The results are intended to show how well current evidence on preventing PONV and pain is applied in everyday practice and where care can be improved.

Study Overview

Status

Recruiting

Conditions

Detailed Description

BACKGROUND Bariatric surgery is common in Sweden with 4,000-5,000 procedures per year. Data on each operation are recorded in the Swedish Perioperative Register (SPOR), covering more than 90% of all surgical procedures in Sweden with automatic data transfer from hospital IT systems, and in the Scandinavian Obesity Surgery Registry (SOReg), with a coverage of approximately 98% of bariatric surgery. Postoperative nausea and vomiting (PONV) and pain are frequent after bariatric surgery. Evidence-based guidelines exist, but 25-40% of surgical patients still experience PONV, and up to 50% may experience severe postoperative pain. Risk factors are validated at a general level but not specifically for bariatric surgery.

OBJECTIVES

  1. To describe the risk of early PONV and pain in the post-anaesthesia care unit (PACU) after primary bariatric surgery.
  2. To identify factors associated with early PONV and pain.
  3. To test the hypotheses that total intravenous anaesthesia (compared with inhalational anaesthesia) and the addition of a regional block are associated with lower risk of PONV or pain in the PACU; that poorer preoperative health-related quality of life (RAND-36) is associated with higher risk of PONV, pain and severe pain; and that PONV or pain in the PACU is associated with higher risk of postoperative complications up to one year after surgery. Separate hypothesis tests are performed for PONV and pain.

DESIGN Exploratory observational cohort study based on registry data. Patients aged 18 years or older with a primary bariatric procedure registered in SOReg during 2018-2027 are identified. Records are linked to SPOR by Uppsala Clinical Research Center (UCR) using personal identity number and date of surgery (+/- 3 days). If several SPOR records fall within the interval, each is included as a separate row with an index variable linking to the SOReg operation. Each individual is assigned a unique serial number and the dataset delivered to the research group contains pseudonymised data only. Data extractions are made at most once per year from 2025; the first analyses cover 2018-2023.

VARIABLES From SOReg: preoperative data (patient characteristics, comorbidity, laboratory values, preoperative work-up, RAND-36), operative data (procedure type, technique, intraoperative complications) and postoperative follow-up up to one year (complications, hospital care, reoperation). From SPOR: patient characteristics, process data, operative data (diagnosis, procedure, anaesthesia type, times, deviations), postoperative data (pain, nausea/vomiting, deviations, level of care) and date of death.

STATISTICAL ANALYSIS Descriptive statistics with univariable and multivariable analysis of associations. Candidate variables include sex, age, comorbidity, preoperative pain, anaesthesia type, procedure type, surgical technique and length of stay. The expected sample is approximately 70% of all bariatric operations in Sweden, about 3,000 patients per year; the main reason for exclusion is expected to be missing PACU registration of pain and/or nausea at some hospitals. As the study includes more than half of the target population, no formal power calculation is performed.

DATA PROTECTION Only pseudonymised data are handled. Data are stored at Umeå University with access restricted to the study researchers, in accordance with current legislation.

Study Type

Observational

Enrollment (Estimated)

30000

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Sweden
      • Sundsvall, Sweden, 851 86
        • Recruiting
        • Sundsvall Hospital, Department of Anaesthesia and Intensive Care
      • Umeå, Sweden, 901 87
        • Recruiting
        • Umeå University, Department of Diagnostics and Intervention
        • Sub-Investigator:
          • Antonio Moraitis, MD
        • Contact:
        • Principal Investigator:
          • Jakob Walldén, MD, PhD
        • Sub-Investigator:
          • Magnus Hultin, MD, PhD
        • Sub-Investigator:
          • Yucel Cengiz, MD, PhD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

All adult patients registered in the Scandinavian Obesity Surgery Registry (SOReg) with a primary bariatric procedure during 2018-2027 and a matching operation record in the Swedish Perioperative Register (SPOR).

Description

Inclusion Criteria:

  • Age 18 years or older
  • Primary bariatric surgery registered in SOReg during 2018-2027

Exclusion Criteria:

  • Revision bariatric surgery
  • If more than one bariatric operation is registered for the same patient, only the primary operation is included

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Adults undergoing primary bariatric surgery in Sweden 2018-2027
Patients aged 18 years or older with a primary bariatric procedure registered in the Scandinavian Obesity Surgery Registry (SOReg) 2018-2027 and a matching operation record in the Swedish Perioperative Register (SPOR).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Incidence of postoperative nausea and/or vomiting in the post-anaesthesia care unit
Time Frame: During the stay in the post-anaesthesia care unit (approximately 0-4 hours after surgery)
Number of operations with registered nausea and/or vomiting in the PACU divided by the total number of operations. Source: SPOR variable "Illamående postoperativt" (postoperative nausea).
During the stay in the post-anaesthesia care unit (approximately 0-4 hours after surgery)
Pain intensity in the post-anaesthesia care unit, numerical rating scale (NRS) 0-10
Time Frame: During the stay in the post-anaesthesia care unit (approximately 0-4 hours after surgery)
Median NRS score (0 = no pain, 10 = worst imaginable pain). Source: SPOR variables "Smärta inom 1 tim efter ankomst UVA" (pain within 1 hour of PACU arrival) and "Smärta postoperativt, högsta" (highest postoperative pain).
During the stay in the post-anaesthesia care unit (approximately 0-4 hours after surgery)
Incidence of severe pain in the post-anaesthesia care unit
Time Frame: During the stay in the post-anaesthesia care unit (approximately 0-4 hours after surgery)
Number of operations with NRS >= 7 divided by the total number of operations.
During the stay in the post-anaesthesia care unit (approximately 0-4 hours after surgery)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Proportion of patients with postoperative complications, unplanned hospital care or reoperation - 6 weeks
Time Frame: Up to 6 weeks after surgery
Complications (including Clavien-Dindo grade), unplanned hospital care and reoperation as registered in SOReg at the 6-week follow-up.
Up to 6 weeks after surgery
Proportion of patients with postoperative complications, unplanned hospital care or reoperation - 1 year
Time Frame: Up to 1 year after surgery
Complications (including Clavien-Dindo grade), unplanned hospital care and reoperation as registered in SOReg at the 1-year follow-up.
Up to 1 year after surgery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Umeå University

Collaborators

Västernorrland County Council, Sweden
The Scandinavian Obesity Surgery Registry

Investigators

  • Principal Investigator: Jakob Walldén, MD, PhD, Umeå University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 1, 2025

Primary Completion (Estimated)

December 31, 2027

Study Completion (Estimated)

December 1, 2028

Study Registration Dates

First Submitted

August 27, 2026

First Submitted That Met QC Criteria

August 27, 2026

First Posted (Actual)

September 1, 2026

Study Record Updates

Last Update Posted (Actual)

September 1, 2026

Last Update Submitted That Met QC Criteria

August 27, 2026

Last Verified

August 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • BAROSPOR-2025-01
  • 2025 (U.S. NIH Grant/Contract: Faculty of Social Sciences Scientific Grant at the University of Gdańsk)
  • 2025-00877-01 (Other Identifier: Swedish Ethical Review Authority (Etikprovningsmyndigheten))

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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