Background In 2010, guidelines published by the National Institute for Clinical Excellence (NICE) suggested a change in the way patients with stable chest pain of suspected cardiac origin were investigated. These guidelines removed exercise treadmill testing from routine use and introduced cardiac CT to regular use.
Objective To investigate whether these guidelines had improved our service provision by reducing the number of further investigations required to make a diagnosis, and to see if our costs had increased now that the less expensive exercise treadmill tests were not recommended.
Methods Clinic letters were used to assess patients pretest likelihood of coronary artery disease for two six-month cohorts of consecutive patients seen in the rapid access chest pain clinic (January–June 2010 and July–December 2011) using NICE published methodology, and to ascertain which investigations patients had. Using NICE modelled costs, we generated comparative hypothetical costs for each cohort and an average cost per patient.
Results In the January–June 2010 cohort, 435 patients with chest pain were seen, and in July–December 2011, 334 patients were seen. In the pre-NICE guidelines cohort, 23% of patients required two investigations as compared with 11.4% in the post-NICE guidelines cohort, with no patient requiring three investigations as compared with 3% in the original cohort. There was no significant increase in costs per patient in the post-NICE guidance group.
Conclusions Implementing NICE guidance reduced the number of investigations needed per patient, and did not prove more expensive for our department in the short term.
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In the UK, as in many other countries around the world, coronary artery disease (CAD) remains a major diagnostic, clinical and economic challenge. There have been many changes in the technology and guidelines available to clinicians when assessing patients with chest pain of suspected cardiac origin in the outpatient clinic. National Institute for Clinical Excellence (NICE) published recommendations on the assessment of patients with stable chest pain in the UK in 2010 and suggested a new diagnostic pathway based on newer technologies and a meta-analysis of the economic and scientific data. This guideline aimed to introduce a system that was more accurate and economically efficient by suggesting the removal of exercise treadmill testing for the diagnosis CAD as well as defining the need for, and the appropriate investigation based on, a standardised risk assessment model. The new model is illustrated in box 1 and is applicable for patients presenting with typical or atypical angina, as those presenting with non-cardiac chest pain are not recommended to undergo further investigation unless clinical suspicion is raised based on the history or risk factors.1
Estimated pretest likelihood of coronary artery disease (CAD), National Institute for Clinical Excellence recommended diagnostic test algorithm
>90% No further investigations needed in patients presenting with typical angina to confirm CAD but if atypical pain, testing still required to confirm a diagnosis of CAD
61–90% coronary angiography
30–60% functional test (stress echocardiography, MPS SPECT or stress MRI)
10–29% calcium scoring followed by CT angiogram if deemed necessary
<10% no further investigations needed to confirm the diagnosis
The requirement for these tests can then be calculated from the age and sex-specific table below (figure 1) taking into account risk factors, such as smoking, diabetes, hypercholesterolaemia, type of chest pain and electrovardiogram (ECG) changes.2
This change in cardiology investigations has been possible mainly due to a rapid improvement in diagnostic technology and its availability in many UK hospitals. The diagnostic accuracy of cardiac CT, myocardial perfusion imaging and stress echocardiography have superseded exercise tolerance testing, and these tests have emerged as an alternative to invasive angiography in appropriate patients because of their improved safety profile.
We previously published an observational study2 in 2011 to model the expected impact in the chest pain clinic service, as departments around the UK moved to introduce the recommendations from NICE. We used NICE-prescribed risk assessment model to predict how patients would follow the new investigation pathway, and what investigations would be most requested in a typical cardiac centre. We predicted that over a quarter of chest pain clinic patients would need no further cardiac investigations, 30% would require functional imaging, 22% cardiac CT and 21% invasive angiography to confirm or exclude a diagnosis of angina.
As in many hospital trusts, we have aimed to provide a NICE-compliant service for our patients. We have thus had to develop an outpatient cardiac CT service with two sessions a week, increased our stress echocardiography service to include at least one session a day to cope with the service expansion, and have plans to introduce a perfusion MRI service.
One of the key concerns of many was whether hospitals would actually phase out exercise tolerance tests (ETTs), having made considerable investment in the staff and technology and acquired long experience with the technique. Some physicians had felt that despite the guidance, there was value in continuing to use ETTs in the assessment of patients presenting with stable chest pain for a potential variety of reasons.3 ,4 The other major concern was whether there would be a large rise in hospital costs as patients underwent more expensive initial tests, such as cardiac CT. This is despite the hoped-for long-term savings through superior testing accuracy and, therefore, reduced supplemental testing.
Since our original study, and nearly two years since NICE published its guidelines, there has been very little data to emerge on the change that this has made to many departments either in changing practice, the service cost or in superior patient outcomes. We therefore took our original cohort and reviewed their notes to see what investigations they had prior to the introduction of a NICE-compliant service, and to look at the economic burden and the clinical outcomes. We then took a second six-month cohort following the service expansion to see if NICE guidance had been implemented, and whether this was economically more efficient and resulted in fewer tests being needed for patients to diagnose or exclude CAD. Information about our trust is shown in box 2.
Information about our centre—Aintree Cardiac Centre, University Hospital Aintree, Liverpool
This is an 819-bedded NHS Foundation Trust Hospital with a catchment area of 33 miles in urban Liverpool serving a population of approximately 330 000.
The trust provides all standard acute medical services, and the cardiology department in particular, provides a range of diagnostic services including dobutamine, treadmill and bicycle stress echocardiography, nuclear imaging and invasive angiography. There are: 10 full-time consultants with 1 part-time consultant with a pooled expertise in invasive angiography, echocardiography, nuclear cardiology, cardiac CT and cardiac MRI with support from the radiology department.
Prevalence of coronary artery disease (CAD)
The prevalence of CAD is higher than the national average (9.4% vs 6.4%).
Rapid access chest pain clinics
The cardiology directorate runs six rapid-access chest pain clinics a week, and sees, on average, six new patients per clinic.
Materials and methods
This study was a single centre study carried out at University Hospital Aintree NHS Foundation Trust. The inclusion criteria for our original six-month cohort of patients from the rapid access chest pain clinic (RACPC) service has been previously published,2 and this group had their electronic case notes reviewed to see what investigations they had performed for the potential diagnosis of angina. The RACPC service is designed for patients who are not known to have CAD presenting with chest pain and who require rapid assessment for potential significant coronary disease. We used our existing data on this group's pretest likelihood of CAD and demographics to compare with our second group.
We then retrospectively collected six months’ data on all consecutive RACPC attendees from July 2011 to December 2011 to look at the effect of NICE guidance on our practice. Clinic letters from RACPC clinics include the full history of the patient's chest pain and risk factors profile. It also includes details of the 12-lead electrocardiogram and management plan for each patient. These letters are stored in the electronic database of each individual patient. Two junior doctors, one cardiovascular research fellow and a specialist registrar collected data from clinic letters after training sessions with senior study investigators.
The definition of chest pain was left as broad as possible because of the variable clinical presentation of CAD, and any patient presenting with any type of self-defined pain, tightness or discomfort anywhere in the chest was included. Chest pain was then defined as typical, atypical and non-anginal based on the system shown in figure 1, and adapted from NICE guidance.
We collected relevant clinical data on each patient based on NICE document, including age, sex, the presence of risk factors as identified by NICE (hypercholesterolaemia-total cholesterol >6.47 mmol/l), current smoker and diabetes mellitus). Twelve-lead ECG changes as identified by NICE, such as resting ST-segment depression/flattening, left bundle branch block, Q-waves or T-wave inversion or flattening, were also noted from the RACPC letter.
We used this data to calculate a pretest likelihood of CAD for each patient, and then looked at the investigations they had to try and confirm or exclude a diagnosis of angina. A patient was considered to have required a second investigation where the referring clinician had felt there was diagnostic doubt, and requested a further investigation to confirm the diagnosis. Investigations done to elucidate the significance of any disease such as a perfusion scan following a positive coronary angiogram, were not included as it was not done to diagnose CAD.
Patients with non-anginal pain were included in the analysis if as per NICE guidelines, clinical suspicion was raised based on other aspects of the clinical history or risk factor profile, and the attending physician documented their concerns that the patient may have CAD as the cause of their pain.
Economic comparison data
As there is currently no agreed UK tariff in place for investigations such as cardiac CT, we used modelled economic costings for the investigations undertaken at our hospital from previously published articles.5 ,6 The modelled costs are shown below:
Exercise Tolerance Test £66
Cardiac CT £206
Stress Echocardiography £109
Myocardial Perfusion Scan £293
Invasive Angiography £850
This study was part of an ongoing service evaluation audit at our centre and was, therefore, approved by the local audit and clinical governance department. According to current practice, formal research ethics committee approval was not needed.
Using the clinical information obtained, patients’ pretest likelihood of CAD was calculated using NICE guidance.1 Patients without any of the risk factors identified by NICE or without any ECG changes meeting NICE criteria were allocated to the low-risk portion of the model depending on age and sex. NICE guidance states that only the absence of cardiovascular risk factors or ECG changes equates to low-risk category. All patients with one risk factor or more, or ECG changes, were therefore assigned to the high-risk category portion of the model again based on age and sex. This is similar to our previous publication, and thus allows reasonable comparison of the two cohorts.
Results were obtained for the age distribution, sex distribution and the presence of the risk factors outlined by NICE in our patient cohort. Each patient had a pretest likelihood of CAD calculated according to NICE risk factor model.
We then took the initial investigation each patient had and any subsequent investigations needed to confirm CAD, and compared our original cohort before the introduction of NICE guidance with our second cohort aiming to use a NICE-compliant service.
Finally, using the economic modelled costs, we calculated the average cost of initial investigations for each patient by respective CAD likelihood groupings and the investigative cost average per patient overall in both cohorts.
Excel 2007 (Microsoft Corporation, USA) spreadsheet was used for initial data collection, calculation of averages, SDs and graph production. SPSS V.12 (IBM, USA) was used to perform an unpaired t test to check for statistically significant differences in the average values for age, sex distribution and the average cost of investigations required per cohort. We then used a χ2 test to compare the number of patients requiring multiple investigations in each group.
In our first cohort between January and June 2010, 500 patients were reviewed, and in our second cohort, 530 patients were reviewed in RACPC between July 2011 and December 2011.
In the first group, 65 patients were excluded and in the second 196 patients were excluded as they did not have chest pain as the presenting symptom. The age, sex and average pretest likelihood of CAD, were not statistically significant and different between cohorts (p>0.05 for all). Demographics are shown in table 1.
Patient presentation by type of chest pain
figure 2 shows a breakdown of the percentage of types of chest pain in patients presenting to the clinic based on the information and guidelines laid down by NICE. There was quite a variation in the number of patients presenting with atypical pain, which is consistent with the reported variation in previous rapid access clinic audits.7–10
Investigations requested versus NICE recommendations
Table 2 shows the respective CAD likelihood groupings identified by NICE as requiring different investigations and the total number of patients seen in each six-month period.
Figure 3 shows that there has been a large rise in the number of patients not being referred for further investigations, particularly in the very low-risk and in the very high-risk groups, something NICE guidelines have emphasised clearly. We have also seen a massive drop across all groups except one in the number of ETTs requested, another key point in NICE guidance.
In the original cohort, 23% of patients required two investigations to confirm or exclude a diagnosis, as opposed to 11.4% in the aimed-for NICE-compliant service, and no patient required three investigations as opposed to 3% in the original cohort which is a significant reduction in the average number of tests per patient (p<0.05 for both).
We calculated the investigational costs using the previously referred to modelled costs to produce total costs, and then average costs for the two cohorts, shown in table 5.
Using a t test, there was no significant difference in the average cost per patient in either of the cohorts overall. There was, however, a reduction in the average cost in the high-risk and low-risk groups solely due to the fact that fewer investigations were requested as per NICE guidance. In the groups from 10% up to a 90% likelihood of CAD, there was an increase in average costs mainly due to the fact that ETTs were being replaced as an initial investigation by other more expensive and more accurate tests such as cardiac CT or stress echo. The average cost breakdown per patient in the respective CAD likelihood groupings group is shown in figure 4.
This study shows that progress has been made towards implementing a fully NICE-compliant stable chest pain investigation service in our trust, and that this has, as expected, resulted in fewer patients needing investigations and second investigations with a cost saving per patient seen despite a reduction in the use of less expensive ETTs.
The main focus of our study was to determine the clinical and economic implications that NICE guidance on stable chest pain would have in the RACPC. Despite, the progress made, we were still not fully compliant with the guidelines issued by NICE after 12 months. From our data, the initial finding, is that ETT is falling out of regular use in chest pain evaluation, and this is important based on the large volume of evidence showing little incremental value for ETT over clinical judgement.11 This has been important for our department as it has led to a reduction in the number of patients requiring more than one investigation, which can cause delay, be time consuming, expensive and worrying for patients concerned that they may have heart disease. It has been our experience that using NICE guidance has led to an increase in the number of patients undergoing no investigations, and this is an important step in reaffirming the role of good clinical assessment in an era where we have come to expect to always perform a test.
In terms of the clinical implications at our trust, we have seen a large increase in the number of patients being referred for functional investigations, such as myocardial perfusion scans and stress echocardiography, and we have had to adapt to this increased service burden. We envisage the clinical impact of the replacement of ETTs for diagnostic tests with a better sensitivity will require an initial period of adaptation in many departments to facilitate switching to a much higher number of functional tests and cardiac CT. It is likely to mean patients wait longer for their initial investigation compared with a treadmill-led approach, but that they more often won't need a second investigation after this.
The other key impact area we wished to review in our study was the initial economic impact on our department especially in the current financially difficult climate, and whether a change from a low-cost ETT-led model to a more complex and expensive strategy would prove expensive at least initially. In our initial follow-up period, we have shown that the cost on average per patient has not risen and, while not statistically significant, has fallen, and it is hoped that it will fall further, as requesting doctors gain greater experience with CT and request less confirmative secondary tests. The majority of the cost saving that we were able to make between the two cohorts was due to the fact that no patients in the cohort following NICE guidelines needed three investigations, fewer patients needed two investigations, and more patients had no investigations as clinical judgement alone could be used to diagnose or exclude CAD. It may be that in the future, we will reduce our burden on invasive coronary angiography as a confirmative test of choice and use CT angiography, thus reducing our costs even further. There has already been some evidence from other sources that this is likely to be the case.12 ,13 ,14
From our data, assuming most trusts to have access to the technology and expertise, the new CT and functional imaging-led strategy should prove at the very least, cost-neutral initially, and it is hoped in the long term significantly cheaper through improved diagnosis and prevention of major CAD events and through early preventative treatment. The data from our cohort should prove generalisable to most other hospitals in the NHS that operate a RACPC service even if not all have the full spectrum of investigations as we are implementing a national guideline, and ours is a large teaching hospital similar to many hospitals across the country. Despite the national guidance, some patients will have a contraindication to, for instance, cardiac CT or stress echo, and there will also be situations when a consultant cardiologist is able to employ clinical judgement and decide that a patient may be better off with one test rather than another. These factors and patient preference will mean that from trust to trust there will be a degree of variability on the exact investigation or not that patients undergo, though we feel the general trends we have shown will be replicable.
To our knowledge, this is the first study looking at the economic and clinical impact of NICE guidance on stable chest pain using actual patient experiences. Apart from our earlier study, there has only been one other study looking at the implications of NICE guidance and using hypothetical data, this suggested an increase in costs.15 This may be because they have not factored in the need for more than one investigation in patients where the first test is non-conclusive.
Our study was limited, in as much as it is a single site study, and that does allow for the possibility of a degree of bias. NICE guidance was also not fully implemented by some of our physicians, and so we cannot extrapolate as to how much cost savings or costs increase would result from a fully compliant service. What we can identify from our study with real-world practice is that moving towards a NICE-compliant service has certainly not been more expensive for us, and has definitely meant fewer additional tests for patients.
In our study, there was a high proportion of people referred with non-cardiac chest pain in the initial cohort, which dropped significantly in the second cohort. This may reflect an abnormal period in our referral history, or may represent better triage from primary care following NICE guidance, and currently, we cannot be sure which is the case, or if this is a long-term trend, and this maybe is an area for further study.
We must also point out that our hospital is in an area of higher than the national average of CAD,16 and that may have meant that we performed more stress echocardiography than cardiac CT with a cost saving that would not be realised in areas of lower prevalence.
As part of our study, we have included patients with a greater than 90% likelihood of CAD who went on to have further investigations, and we accept that this may have been done to assess the severity of disease as opposed to confirm the diagnosis in line with NICE. This may have introduced some error to the results from this particular group but it could not always be confirmed from the clinician's letter whether it is was a confirmatory or prognostic test.
At the moment, what we do not know is if this new approach has made an impact on clinical outcomes, as the follow-up period for our two cohorts is very short. We have reduced he number of investigations that patients require, but we don't know if that translates into fewer myocardial infarctions, unexpected hospital admissions or a reduction in overall mortality. This long-term outcome data and the longer-term economic impact should be the focus of further study to confirm the data modelling that NICE used to draw up the recent guidance. Some of the controversies discussed at length when NICE outlined their guidance may be able to be addressed with longer-term data, such as the long-term economic costs, clinical outcomes and patient feedback using the new paradigm.3
Overall, reducing ETT usage and incorporating NICE recommendations has allowed us to reduce on average the number of tests RACPC patients require to diagnose or exclude CAD. This change has not resulted in any increase in our departmental budget costs or a rise in average investigation cost per patient. This should hopefully be a change that will be mirrored in many other UK NHS hospital trusts. NICE guidance, has proven to be both economically and clinically beneficial in the rapid-access chest pain setting, and it is likely the benefits will increase over time compared with the previous paradigm.
Moving towards a NICE-compliant service has not resulted in increased costs to our department.
Using NICE-recommended testing algorithm results in fewer patients needing more than one test.
As a result of guidance from NICE, many patients now do not undergo any form of test to diagnose coronary artery disease.
Current research questions
Will a NICE-compliant service in the rapid access chest pain clinic prove cost saving in the long term?
Will the change from NICE lead to a reduction in adverse cardiac events in the long term?
What are the reasons that some physicians still use exercise tolerance testing in stable chest pain?
Cooper A, Timmis A, Skinner J. Assessment of recent onset chest pain or discomfort of suspected cardiac origin: summary of NICE guidance. BMJ 2010;340:c1118.
Garg P, Ashrafi R, Feeney L, et al. Impact on service provision for non-invasive cardiac imaging following NICE recommendations: an observational study. Postgrad Med J 2011;87:445–9.
Mowatt G, Cummins E, Waugh N, et al. Systematic review of the clinical effectiveness and cost-effectiveness of 64-slice or higher computed tomography angiography as an alternative to invasive coronary angiography in the investigation of coronary artery disease. Health Technol Assess 2008;12:iii–iv, ix-143.
Contributors RA wrote the paper. SR, TD and AA did the data analysis. PW and GD helped design the study and edited the final draft.
Competing interests None.
Ethics approval University Hospital Aintree Audit Department.
Provenance and peer review Not commissioned; externally peer reviewed.