provides a concise summary of this evidence and refers readers to comprehensive research reviews and landmark studies.
The chapters that follow focus instead on the second and third questions. For example, the second question entails not only demonstrating whether particular risk factors are more common in the United States than elsewhere, but also whether they have different effects on health outcomes. Countries with the same levels of hypertension (in untreated populations) or the same levels of poverty may experience different health outcomes if, respectively, one country performs better in controlling blood pressure or has a stronger safety net to help poor people avoid health complications. Although we did not systematically examine these differential effects, we did consider them when we knew there was some evidence available. For example, Chapter 6 reviews evidence that the lack of a college degree may have greater health consequences in the United States than elsewhere.