International Variation in Health Status Benefits in Patients Undergoing Initial Invasive Versus Conservative Management for Chronic Coronary Disease: Insights From the ISCHEMIA Trial.

Background: The ISCHEMIA trial (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) demonstrated greater health status benefits with an initial invasive strategy, as compared with a conservative one, for patients with chronic coronary disease and moderate or severe ischemia. Whether these benefits vary globally is important to understand to support global adoption of the results.

Methods: We analyzed participants' disease-specific health status using the validated 7-item Seattle Angina Questionnaire (SAQ: >5-point differences are clinically important) at baseline and over 1-year follow-up across 37 countries in 6 international regions. The average effect of initial invasive versus conservative strategies on 1-year SAQ scores was estimated using Bayesian proportional odds regression and compared across regions.

Results: Considerable regional variation in baseline health status was observed among 4617 participants (mean age=64.4±9.5 years, 24% women), with the mean SAQ summary scores of 67.4±19.5 in Eastern Europe participants (17% of the total), 71.4±15.4 in Asia-Pacific (18%), 74.9±16.7 in Central and South America (10%), 75.5±19.5 in Western Europe (26%), and 78.6±19.2 in North America (28%). One-year improvements in SAQ scores were greater in regions with lower baseline scores with initial invasive management (17.7±20.9 in Eastern Europe and 11.4±19.3 in North America), but similar in the conservative arm. Adjusting for baseline SAQ scores, similar health status benefits of an initial invasive strategy on 1-year SAQ scores were observed (ranging from 2.38 points [95% CI, 0.04-4.50] in North America to 4.66 points [95% CI, 2.46-6.94] in Eastern Europe), with an 88.3% probability that the difference in benefit across regions was <5 points.

Conclusions: In patients with chronic coronary disease and moderate or severe ischemia, initial invasive management was associated with a consistent health status benefit across regions, with modest regional variability, supporting the international generalizability of health status benefits from invasive management of chronic coronary disease.

Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01471522.