Background The RACPC is a well-established “one-stop” service, with goal to identify patients with stable chest pain due to coronary artery disease (CAD) and quickly reassure those with non-cardiac pain. In March 2010, NICE published a new guideline, which advocates assessing likelihood of CAD based on age, gender, history and risk factors (RF). If estimated likelihood is >60%, invasive coronary angiography (ICA) is recommended as the first-line diagnostic investigation. If estimated likelihood is 30%–60%, functional imaging is recommended. If estimated likelihood is <30%, CT calcium scoring CT coronary angiography (CTCA) is recommended. Significantly, the guideline discourages the use of ETT to diagnose or exclude stable angina in patients without known CAD.

Methods 167 consecutive patients referred to RACPC between October 2009 and March 2010 were retrospectively assessed for likelihood of CAD according to the new NICE guideline. Choice of investigations and eventual outcome (confirmed CAD vs no evidence of CAD) were compared between subgroups defined by estimated likelihood of CAD. An economic analysis of cost of investigation per patient was undertaken using current Payment by Results national tariffs.

Results Our patient population had a high prevalence of RF with 38.1% having a total of three or more RF. Consequently 23.2% of patients had an estimated likelihood of CAD of <30%. 27.4% had an estimated likelihood of 30%–60%. 49.4% had an estimated likelihood of >60%. 7.2% of patients were lost to follow-up. 14.4% of patients were ultimately confirmed to have CAD on ICA, which correlated with pre-test estimated likelihood. 6% of patients with likelihood <30%, 8.7% of those with likelihood 30%–60% and 23.2% of those with likelihood >60% were confirmed to have CAD. Average cost of investigation per patient was £528. A negative ETT resulted in average cost per patient of £347. An inconclusive ETT resulted in higher cost (£728) as did inability to exercise (£435) due to the need for further investigations. A positive ETT resulted in average cost of £1174 due to the high cost of ICA. Were the NICE guideline strictly applied to our patient population, average cost per patient would have been substantially higher at £838 (£362 per patient if likelihood <30%, £566 if likelihood 30%–60% and £1218 if likelihood >60%). Overall this corresponds to a 60% increase in cost.

Conclusion The 2010 NICE guideline appears to significantly overestimate the true risk in our patient population. Were the guideline strictly applied, almost half of our patients would proceed to ICA as a first-line investigation, but many of them would be found to have unobstructed coronary arteries. As ICA is an expensive investigation, this would inevitably result in a significant increase in average cost per patient. Relatively few patients would be eligible for CTCA, which is an excellent non-invasive “rule-out” test for CAD and relatively inexpensive compared with other investigations.

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