Pre-operative Haemoglobin A1c (HbA1c) in diabetic patients undergoing major surgery: An investigation into current practice

Abstract

BackgroundWithin the cohort of surgical patients, 10–15% have diabetes (Barker, 2015). These patients are at an increased risk of perioperative complications due to their often unrecognised hyperglycaemia and poor perioperative management (Sampson, 2007). The current guidelines by the 2011 National Health Service (NHS) Diabetes is that glycaemic control should be checked for these patients via a haemoglobin A1c (HbA1c) at the time of referral to surgery (Barker, 2015), with elective surgery being deferred if it is greater than 8.5%. However, as yet, there is no universal guideline regarding this. At Western Health -a single hospital system in Victoria, Australia- new guidelines have been implemented as of 2018, mandating that HbA1c is measured within 3 months of a patient's surgery and that elective surgery is delayed if the value is greater than 9.0%. As this is a recent initiative, it may not reflect nation-wide practice and we assume many institutions are yet to implement their own guidelines. We therefore aim to investigate what the standard practice was prior to these guidelines, by recording the levels at which HbA1c was documented before a patient's surgery, as our primary outcome. This is with the assumption that these results may still reflect patterns in a number of hospitals nation-wide. Using these levels as a baseline, we will then be able to compare the results in a future investigation, following the implementation of the guidelines, and assess institutional compliance. The hypothesis is that pre-operative HbA1c is not measured in diabetic patients, within 3 months of their major surgery. As a secondary outcome, we will also explore whether a physician's decision to measure a patient's HbA1c is influenced by whether or not they are receiving insulin therapy. MethodsWe identified all adult patients aged 45 years and older, with diabetes, who underwent major surgery at Western Health during 2016. Fifty patients were then collected from four surgical specialities including vascular, general surgery, urology and orthopaedics, and it was noted whether their HbA1c was measured within 3 months of their surgery. ResultsOf 200 patients, only 71 had a measured HbA1c within 3 months, with noticeable variation among the specialities. HbA1c was measured for 22% of urology patients, 28% for orthopaedics, 36% for general surgery and 56% for vascular. There was also a strong association showing if a patient is on insulin therapy they are more likely to have a measured HbA1c. ConclusionsHbA1c is not measured for the majority of patients within 3 months of their surgery and this decision is based on a clinician's judgement. There is therefore a need for formal institutional guidelines.