Systematic review, meta-analysis and economic modelling of ...

Assessment of diagnostic and prognostic accuracyCTCA died on follow-up. There were 2 out of 43 and 12 out of 185 non-fatal MIs among those patientswith positive or intermediate CTCA in the cohorts of Rubinshtein 135 and Schlett. 136 The cohorts of Miller 134(n = 18), Goldstein 131 (n = 32) and Hollander 133 (n = 54, follow-up to 30 days) reported no cases of deathor non-fatal MIs among those patients with positive CTCA. It could be argued that the process outcomes(PCI and CABG) prevented subsequent death or non-fatal MI in those with positive CTCA, but this isdifficult to determine.In the study of Schlett et al. 136 patients and carers were blind to CTCA findings, so any association betweenCTCA findings and process events (PCI and CABG) was not simply due to physicians acting on CTCAfindings. Schlett et al. found that CTCA predicted MACEs, even after adjustment using a clinical risk scoreincorporating ECG and troponin measurement. Thus, this study provides the best evidence that CTCAprovides independent prognostic value beyond routine clinical assessment.The study of CT CAC scoring 151 reported that 9 out of 91 patients with a CAC score of > 0 had MACEs(two MI and nine PCI), compared with 0 out of 82 with a CAC score = 0.The results of meta-analysis of CTCA prognostic studies are shown in Figure 30 (positive and intermediatevs negative) and Figure 31 (positive vs intermediate and negative). Only studies that definitely reporteddata from patients with positive and negative CTCA are included in this analysis. Meta-analysis of thefive studies with analysable data showed a RR for MACEs of 3.1 (95% CrI 0.3 to 18.7) for positive andintermediate scans compared with negative scan and 5.8 CrI (95% Crl 0.6 to 24.5) for positive scancompared with intermediate or negative scans. These estimates are subject to considerable uncertainty,with the CrI including one (i.e. no association) for both estimates. Taken alongside the limitations relatingto patient selection and process outcomes suggests that there is currently only weak evidence that CTCAprovides prognostically useful information in patients with suspected ACS.Prognostic studies of exercise electrocardiographyTable 29 shows the characteristics of the prognostic studies of exercise ECG. Sample sizes ranged from 28to 1000. The mean age (30–60 years) was relatively young, reflecting the selection of low-risk patients inmany of the cohorts. Follow-up ranged from 30 days to > 12 months. There was no consistency in thedefinitions and reporting of MACEs, with some studies reporting composite outcomes only and othersreporting outcomes separately with no indication of whether or not some patients had suffered multipledifferent adverse outcomes.Table 30 shows the quality assessment of the exercise ECG studies. The population age and sex werealways well described but most studies did not clearly define their inclusion criteria. MACEs were definedin the methods section in all but one study and was defined and identified independent to the index testin all studies. No study undertook multivariate analysis to determine the independent prognostic value ofexercise ECG.Table 31 shows the outcomes of the studies of exercise ECG. Most of the studies reported inconclusiveresults separately from positives and negatives but three studies 142,147,148 reported them with positives, onewith negatives, 139 and it was unclear in one study whether or not there were any inconclusive results. 150Overall, MACE rates varied between the studies, reflecting variation in patient selection criteria and thedefinition of MACEs. Rates were generally low among patients with negative ETT results and there wassome evidence that positive tests identified higher-risk patients. However, higher rates of revascularisationamong patients with positive ETT may reflect physician awareness and expectation of a need forrevascularisation. There was evidence from some studies that death and MI rates were higher amongpatients with positive ETT, although the modest numbers limit the conclusions that may be drawn.The results of meta-analysis of prognostic studies of exercise ECG are shown in Figure 32 (positive andinconclusive vs negative) and Figure 33 (positive vs inconclusive and negative). Meta-analysis showed aRR for MACEs of 8.4 (95% CrI 3.1 to 17.3) for positive and inconclusive compared with negative and74NIHR Journals Library