Heartbeat: highlights from the issue.

Randomized controlled trials increasingly recruit patients globally to facilitate recruitment and to improve validity and applicability. However, patients from countries with different developmental status may differ in terms of clinical profiles, adherence to prescribed therapy and access to health care facilities. Further, these differences may impact patient outcomes. In this issue of Heart Professor Prabhakaran and colleagues (see page 279) (figure 1) report the influence of developmental status of individual countries, as defined by the United Nations’ Human Development Index (HDI), on clinical outcomes of patients with Acute Coronary Syndrome (ACS) in a multinational study, the Trilogy ACS. Despite uniform study eligibility criteria, baseline characteristics differed significantly among patients from different HDI-classified countries. These baseline differences in turn were associated with differential outcomes. The authors conclude that geographical and other country-level factors variations in study populations need to be taken into account when designing, conducting and analyzing trials. In the companion editorial, Dr Banerjee (see page 245) systematizes how this heterogeneity in developmental status can influence both internal and external validity of a clinical trial. He also opens the discussion to a much broader ethical issue: what is the role of testing new, expensive drugs in countries with low developmental status, where access to other proven and low-cost therapies is frequently absent? (figure 2). Air pollution is associated with higher rates of cardiovascular morbidity and mortality. In a study from Beijing by Professor Lui and colleagues (see page 257), a clear dose-response relationship between the air concentration of fine particulate matter (PM2.5) and ischemic heart disease mortality was demonstrated over a 2 year period based in a very large ischemic heart disease database. The authors conclude: “Our findings provide a rationale for the urgent need for stringent control of air pollution to reduce PM2.5 concentration” (figure 3). Dr Pope comments in an editorial (see page 248) that “cohort and related studies that evaluate effects of long-term exposure are also needed to help provide a more complete understanding regarding the shape of the exposure–response Figure 1 Cumulative Kaplan–Meier failure estimates of the composite study endpoint by Human Development Index (HDI) classification during the 30-month follow-up period. Black, very-high HDI; blue, high HDI; red, medium HDI.