Health-Status Outcomes with Invasive or Conservative Care in Coronary Disease

Abstract

Background: In the ISCHEMIA trial, an invasive strategy with angiographic assessment and revascularization did not reduce clinical events among patients with stable ischemic heart disease and moderate or severe ischemia. A secondary objective of the trial was to assess angina-related health status among these patients.

Methods: We assessed angina-related symptoms, function, and quality of life with the Seattle Angina Questionnaire (SAQ) at randomization, at months 1.5, 3, and 6, and every 6 months thereafter in participants who had been randomly assigned to an invasive treatment strategy (2295 participants) or a conservative strategy (2322). Mixed-effects cumulative probability models within a Bayesian framework were used to estimate differences between the treatment groups. The primary outcome of this health-status analysis was the SAQ summary score (scores range from 0 to 100, with higher scores indicating better health status). All analyses were performed in the overall population and according to baseline angina frequency.

Results: At baseline, 35% of patients reported having no angina in the previous month. SAQ summary scores increased in both treatment groups, with increases at 3, 12, and 36 months that were 4.1 points (95% credible interval, 3.2 to 5.0), 4.2 points (95% credible interval, 3.3 to 5.1), and 2.9 points (95% credible interval, 2.2 to 3.7) higher with the invasive strategy than with the conservative strategy. Differences were larger among participants who had more frequent angina at baseline (8.5 vs. 0.1 points at 3 months and 5.3 vs. 1.2 points at 36 months among participants with daily or weekly angina as compared with no angina).

Conclusions: In the overall trial population with moderate or severe ischemia, which included 35% of participants without angina at baseline, patients randomly assigned to the invasive strategy had greater improvement in angina-related health status than those assigned to the conservative strategy. The modest mean differences favoring the invasive strategy in the overall group reflected minimal differences among asymptomatic patients and larger differences among patients who had had angina at baseline. (Funded by the National Heart, Lung, and Blood Institute and others; ISCHEMIA ClinicalTrials.gov number, NCT01471522.).

Figure 1.. Crude Mean Health-Status Scores in the Overall Trial Population.

Observed mean health-status scores from randomization through 48 months are shown. Shading represents the 95% confidence interval. On the Seattle Angina Questionnaire (SAQ), the SAQ Summary score is obtained by averaging the SAQ Angina Frequency, SAQ Quality of Life, and SAQ Physical Limitation scores; SAQ scores range from 0 to 100, with higher scores indicating better health status. On the Rose Dyspnea Scale, scores range from 0 to 4, with higher scores indicating dyspnea with milder activities. On the European Quality of Life–5 Dimensions (EQ-5D) visual analogue scale, scores range from 0 to 100, with higher scores indicating better health status.

Figure 2.. Distributions of the Expected Differences in SAQ Summary Scores from an Initially Invasive Strategy.

The posterior distribution of effect scores for a typical patient, with a baseline score equal to the population mean and a random effect of 0, is shown.

Figure 3.. Effect of Treatment as a Function of Patients’ Baseline Angina Frequency.

Panel A shows the effect of each treatment strategy on the SAQ Angina Frequency score, measured as the estimated difference (invasive minus conservative) in the mean score, as a function of patients’ baseline SAQ Angina Frequency score. Panel B shows the probability of being angina-free (SAQ Angina Frequency score, 100) at 3, 12, and 36 months if treated with an invasive strategy (red) or a conservative strategy (blue). Shading represents 95% credible intervals.