Today’s PLoS Medicine includes our recent study attempting to answer a simple question: given the rise in many chronic disease risk factors (high blood pressure, cholesterol, diabetes, etc.) in rapidly-developing countries like India and China, which interventions might avert the most deaths from cardiovascular disease?
Some mathematical models have attempted to answer this question in the past, but a problem with prior assessments was that they often only had data at the level of whole countries (assuming all Indians or all Chinese are the same) or even whole regions (like all of South Asia). Yet we know there are vast disparities in risk between rich and poor, men and women, and regions within countries like India and China. Prior studies also made some debatable assumptions, such as assuming that 80% of people in developing countries would have access to medications over periods shorter than five years (!), and that patients treated with medications like statins will have perfect adherence to the medications as well as having healthcare providers who perfectly delivered the medications according to clinical guidelines.
As an alternative, we used large-scale population-representative surveys to inform an alternative mathematical model of myocardial infarctions and strokes in India, which was subsequently validated against longitudinal data from the country. This model incorporated real-world data accounting for differences in populations who have different levels of risk factors (for example, different hypertension rates among urban and rural women, when surveying both groups equally to account for surveillance biases), time trends in risk (since risks are changing among different demographic groups), and data on access, adherence, implementation speed of interventions. We also incorporated a number of details related to tobacco use that were excluded from prior studies—such as the finding that many Indians smoke informal cigarettes called ‘bidis’, which are risky to health but are often missed by standard models focusing only on formally-manufactured cigarettes.
The study found that smoke-free laws and increased tobacco taxes in India would likely yield substantial and rapid health benefits by averting future heart attacks and strokes. Incorporating large-scale meta-analyses of international data, the results also suggest that these two tobacco control strategies would probably be more effective than other measures such as smoking cessation therapies for the reduction of cardiovascular deaths over the next decade in India, and possibly in other low- and middle-income countries. The comparative effectiveness of aspirin, statins and blood pressure drugs was more disappointing, not because the drugs are ineffective at an individual level, but because of real-world levels of access, adherence and proper utilization; but improvements in health system infrastructure may improve that outcome.
Critically, the pharmacological therapies and tobacco prevention strategies appeared to be “synergistic” rather than competing—producing reduced death rates by different mechanisms rather than having overlapping dynamics of “diminishing returns”.