The need for core outcome sets in surgery

By Natalie Blencowe and Jane Blazeby

Compared with pharmaceutical trials, the quality of surgical randomised trials is poor and the evidence base for many surgical procedures remains weak. Reasons for this are multi-factorial including problems with recruitment, blinding, and the fact that surgical procedures are constantly evolving.

Another major difficulty relates to outcome assessment because there are currently no recognised definitions or standards for measuring surgical outcomes, including complications.

Lack of consistent outcomes

A recent systematic review of oesophageal cancer surgery has highlighted the extent of this problem, as not a single outcome was reported across all 122 included papers.

Anastomotic leak was reported in 80 studies but only defined in 28, using 22 different definitions  [1]. Similar problems have been reported in reviews of colorectal cancer, obesity and reconstructive breast surgery [2].

If studies do not all report the same outcomes, or provide definitions, it becomes impossible to accurately synthesise data so that outcomes can be compared between hospitals.

In addition, most studies measure and report surgeon-selected outcomes rather than patient-reported outcomes. This means that patients’ perspectives are often not considered and also that the intervention in question cannot be fully evaluated.

Core outcome sets

One solution is to provide a core outcome set for each surgical condition or procedure.

Core outcome sets contain a minimum agreed set of outcomes to be reported in all studies of a particular condition or procedure, and agreed definitions should also be provided as part of this.

If definitions and outcomes are standardised, meaningful cross-study comparisons can be made which minimises outcome reporting bias.

Developing core outcome sets via COMET

One way of developing core outcome sets is to use Delphi methodology to reach consensus by surveying key stakeholders, including patients.

The Core Outcome Measurement in Effectiveness Trials initiative (COMET) facilitates development of such measures in all areas of healthcare, including surgery. We are developing a core outcome sets for oesophageal and colorectal cancer surgery, for obesity surgery and for breast reconstructive surgery 1, 2.

To achieve this, we are working with the respective sub speciality organisations and with patient support groups. Whilst it is anticipated that clinical and patient-reported outcomes will be included, the final items (and their definitions) are yet to be decided.

If you would like to find out more, please visit our website, or post a question below.

  1. Blencowe NS, Strong S, McNair AG, Brookes ST, Crosby T, Griffin SM, Blazeby JM. Reporting of short-term clinical outcomes after esophagectomy: a systematic review. Ann Surg. 2012; 255(4):658-66.
  2. Potter S, Brigic A, Whiting PF, Cawthorn SJ, Avery KN, Donovan JL, Blazeby JM. Reporting clinical outcomes of breast reconstruction: a systematic review. J Natl Cancer Inst. 2011; 103(1):31-46.


Leave a Reply

Your email address will not be published. Required fields are marked *