Pitfalls in the construction of cancer guidelines demonstrated by the analyses of colorectal referrals

Abstract

INTRODUCTION The aim of this study was to develop a system to compare and validate cancer referral guidelines, identifying the pitfalls in their development and provide a mechanism to evaluate their efficacy.PATIENTS AND METHODS 3302 patients referred from primary care with colorectal symptoms over a 3-year period were assessed. All participants had a comprehensive history obtained via a questionnaire that incorporated all colorectal symptoms. The questionnaires were completed prior to assessment at the hospital. All patients were then assessed at the Colorectal One Stop Clinic (CROSC), underwent investigation and diagnosis achieved. All data were entered into a databank. Current prioritisation guidelines and tools that are used to assess colorectal referrals were applied to this colorectal databank to test their efficacy for cancer detection and referral prioritisation. Sensitivity and specificity for cancer detection and referral rates were assessed.RESULTS Cancer was detected in 156 patients (4.7%). All prioritisation models (NHS guidelines, Weighted Numerical Score [WNS], Netherlands, Harvard, Mersey, and Somerset) differentiated cancer from non-cancer patients. The use of a few symptoms as risk predictors (e.g. NHS guidelines) causes a decrease in specificity in contrast to a comprehensive risk tool, for example, the WNS at a score of 50 (NHS 54.1%, WNS 62.9%). This results in a significantly higher referral rate (NHS 47.6%, WNS 39.4%) and identifies fewer cancers (NHS 80.1%, WNS 85.9%). Non-evidence based modifications of the NHS guidelines (Somerset and Mersey) caused a further deterioration in specificity, which was reflected in an increased referral rate. Using the WNS, which is objective and a continuous scale, allows adaptation of the referral threshold, balancing sensitivity and specificity to the resources available within a hospital. For example, the WNS of ≥ 40 has a sensitivity of 96.8% for cancer detection.CONCLUSIONS Accurate prospective data collection into a data bank allows testing of referral guidelines as well as providing an adjunct to guideline construction.

The fecal hemoglobin concentration, age and sex test score: Development and external validation of a simple prediction tool for colorectal cancer detection in symptomatic patients

“…In the case of the FAST Score, its greatest advantage is simplicity and it could be calculated automatically by laboratory information management systems (LIMS) widely used to report results in laboratory medicine, with or without appropriate interpretative comments added by the LIMS, or through simple calculators developed for the Internet or as easy to download apps, since age and sex are generally available in health care systems and, if not, are easily collected from patients with symptoms prior to referral for colonoscopy along with the f‐Hb. We think the simplicity of this prediction model may encourage the implementation of the FAST Score in comparison with previous developed prediction models for CRC detection that are based on several clinical and analytical variables which must be collected from disparate sources before the model is applied,…”

“…These prediction models, systematically reviewed in detail recently, are calculated from mathematical equations based mainly on symptoms, although information regarding demographics, other variables and results of investigations are sometimes also included . Although their diagnostic accuracy is generally deemed to be satisfactory and better than the existing referral criteria, these prediction models have not been widely implemented, in part due to their complexity and the difficulty of collection of all of the spectrum of variables required …”

Use of a patient consultation questionnaire and weighted numerical scoring system for the prediction of colorectal cancer and other colorectal pathology in symptomatic patients: A prospective cohort validation study of a Welsh population

“…The PCQ and WNS process provides a system with a higher sensitivity and specificity for CRC detection than the current referral guidelines. This is attributed to the benefit of objectively assessing the added risk of cancer when multiple colorectal symptoms co‐exist [6,14]. Furthermore, in the group of patients who score highly a significant proportion are likely to have serious benign conditions such as colitis and polyps (Fig.…”

“…Recent national audits and publications have highlighted problems with their efficacy [4][5][6][7][8][9][10][11]. Poor compliance with the referral guidelines by general practitioners (GP), lack of specificity and overwhelming referrals from primary care have all been identified as common causes of a reduction in the efficiency of the referral process.…”

Criteria for Referring Patients With Outpatient Gastroenterological Disease for Specialist Consultation: A Review of the Literature

“…At this cut-off point, the population urgently referred includes not only patients with cancers but also patients with benign diseases that need urgent management, such as ulcerative colitis and polyps. The use of this questionnaire has been supported by others[18, 47]. An evaluation of the WNS compared with several other tools [13, 15, 23, 35, 40] concluded that the WNS with a threshold of 50 had a comparable sensitivity but a higher specificity than the rest of the tools in detecting cancer, yielding the lowest referral rate.…”