Putting us to the test: An assessment of the agreement between preoperative investigations ordered and evidence-based guidelines at a tertiary level hospital in the Western Cape Province, South Africa – a retrospective record review study

Abstract

Background. Recommendations for preoperative investigations are available worldwide, and are advocated for in an attempt to reduce unnecessary testing, especially in healthy patients undergoing low-risk surgery. However, despite these guidelines, unnecessary preoperative testing still occurs. This is the first South African study comparing preoperative investigations ordered with the recommendations of both the National Institute for Health and Care Excellence (NICE) and local preoperative testing guidelines. Objectives. Primary objectives were to describe the preoperative investigations ordered in patients undergoing elective surgery, compare these with international and local guidelines, and assess the cost of overtesting. Secondary objectives were to assess the frequency of abnormal laboratory results in tests not indicated by the guidelines, as well as to assess patterns in overtesting. Methods. This was a retrospective record review study of American Society of Anesthesiologists (ASA) 1 and 2 patients undergoing elective minor and intermediate surgical procedures in Tygerberg Hospital between November and December 2021. The preoperative investigations of 501 patients were studied, including laboratory tests (full blood count (FBC), urea, creatinine and electrolytes panel and international normalised ratio), point-of-care haemoglobin, chest radiographs (CXRs) and electrocardiograms. Tests were compared with guidelines, and the cost of any overtesting was calculated. Patterns in overtesting were evaluated. Data were sourced from electronic medical records. SPSS version 28 was used to analyse data. Results. A total of 501 patients undergoing elective surgery were included. As many as 89% of the cohort had at least one unnecessary test done (95% confidence interval 85.9 - 91.6). Overall, FBCs and CXRs were the most overtested investigations, being done unnecessarily in one-third of patients. Redundant duplicate testing occurred 177 times. The projected potential cost savings on preoperative investigations if NICE guidelines were followed at Tygerberg Hospital are ZAR857 987 per annum, and ZAR696 515 per annum if the local guidelines are followed. Extra testing as per local guidelines compared with NICE guidelines was mostly unhelpful to reveal additional clinically relevant abnormalities. General surgery patients, patients aged >35 years, ASA 2 patients and females were subject to the highest levels of overtesting (p<0.001). Conclusion. Preoperative testing over and above testing recommended by both international and local guidelines is common, and represents an enormous area for potential cost savings in a resource-limited environment. Additional local studies are required to further expand on overtesting and the factors contributing to it.

Keywords

• Pre-operative investigations
• Over-testing
• NICE guidelines