An analysis of prescription rates of 600 commonly used drugs across the United States is reported in Nature Communications. The results reveal influences of racial composition, state-level healthcare laws, and wealth on prescription choices, with some regions consistently preferring more expensive drugs, even when they have not been proven more effective than cheaper alternatives.

The United States is socially and culturally heterogeneous, with significant disparities and inequality in health metrics such as life expectancy. However, it is not clear to what extent these disparities extend to healthcare.

Andrey Rzhetsky and Rachel Melamed use medical claims data from over 150 million patients in more than 2,000 US counties, to compare the prescription rates of 600 commonly used drugs, including types of opioids, antidepressants, anti-inflammatories and antihypertensives. They show that the prescription data are sufficient to uncover known regional variations in medical care. In addition, the data reveal previously unknown patterns in drug prescription, including a preference for more expensive drugs in some counties, even when efficacy over cheaper alternatives is not demonstrated. For example, urban areas, particularly the corridor from New York to Washington, DC, tend to prescribe more expensive drugs, as do parts of the southeast. However, northern New England and some Midwestern and western states tend to prescribe cheaper drugs.

The authors suggest that differences in patterns of healthcare may be influenced by underlying socioeconomic or commercial factors, possibly including pharmaceutical advertising. These data may aid in the estimation of the effects of interventions in health care policy, they conclude.