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Impact of Obesity on Postoperative Outcomes following cardiac Surgery (The OPOS study): rationale and design of an investigator-initiated prospective study
  1. Christie Aguiar1,
  2. Jeffrey MacLeod1,
  3. Alexandra Yip1,
  4. Sarah Melville2,
  5. Jean-Francois Légaré3,
  6. Thomas Pulinilkunnil4,
  7. Petra Kienesberger4,
  8. Keith Brunt2,
  9. Ansar Hassan3
  1. 1 Cardiovascular Research New Brunswick, Saint John Regional Hospital, Saint John, New Brunswick, Canada
  2. 2 Department of Pharmacology, Dalhousie Medicine New Brunswick, Saint John, New Brunswick, Canada
  3. 3 Cardiovascular Research New Brunswick, and Department of Cardiac Surgery, Saint John Regional Hospital, Saint John, New Brunswick, Canada
  4. 4 Department of Biochemistry and Molecular Biology, Dalhousie Medicine New Brunswick, Saint John, New Brunswick, Canada
  1. Correspondence to Dr. Ansar Hassan; ahassan{at}


Introduction Increasing levels of obesity worldwide have led to a rise in the prevalence of obesity-related complications including cardiovascular risk factors such as diabetes, hypertension and dyslipidaemia. Healthcare providers believe that overweight and obese cardiac surgery patients are more likely to experience adverse postoperative outcomes. The body mass index (BMI) is the primary measure of obesity in clinical practice, without accounting for a patient’s level of cardiopulmonary fitness or muscle mass. The objective of this study is to determine whether fitness capacity of obese cardiac surgical patients and biomarkers, alone or in combination, will help identify patients at risk for adverse outcomes when undergoing cardiac surgery.

Methods and analysis Patients between the ages of 18 and 75 years undergoing elective cardiac surgery are consented to participate in this prospective observational study. Patients will be invited to participate in measures of obesity, functional capacity and exercise capacity assessments, quality of life questionnaires, and blood and tissue sampling for biomarker analysis. The endpoints evaluated are measures other than BMI that could be predictive of short-term and long-term postoperative outcomes. Clinical outcomes of interest are prolonged ventilation, hospital length of stay, renal failure and all-cause mortality. Biomarkers of interest will largely focus on metabolism (lipids, amino acids) and inflammation (adipokines, cytokines and chemokines).

Ethics and dissemination This study has been approved by the institutional review board at the Horizon Health Network. On completion of the study, the results shall be disseminated through conference presentations and publications in peer-reviewed journals. Additionally, the report shall also be diffused more broadly to the general public and the cardiovascular community.

Trial registration number NCT03248921.

  • inflammation
  • morbidity
  • coronary artery bypass grafting
  • adipose tissue
  • atrial appendage
  • globesity

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  • Contributors JM, AY, AH, PK and KB contributed to trial design. TP and JFL provided significant intellectual input. CA recruited patients and prepared the report. AH, JFL, CA and SM assisted with clinical sample collection and processing. JM and AY contributed to statistical design. All authors have read and approved the article.

  • Funding Funding to support this trial is currently provided by the Saint John Regional Hospital Foundation - Chesley Family endowed research grant and John T. Clark endowment, the Dalhousie Department of Surgery Clinical Research Scholarship grant, the New Brunswick Health Research Foundation, the New Brunswick Innovation Foundation, Canadian Diabetes Association and the Heart & Stroke Foundation of Canada to members of the IMPART team (

  • Competing interests None declared.

  • Ethics approval The OPOS trial protocol has been submitted and approved by the institutional committee on human research at Horizon Health Network, Saint John Regional Hospital, New Brunswick Heart Centre & the Nova Scotia Health Authority, Maritime Heart Centre.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Patient consent for publication Not required.