Income Is a Strong Predictor of Drug Purchases for Some Serious Diseases

There are many, many things that rich people buy in larger quantities. It turns out medications for certain serious diseases may be one of them.

A new analysis has found that, for some types of medications, income is a pretty strong predictor of how often someone is picking up a drug to treat an ailment.

The analysis, by GoodRx, a company that tracks prescription drug prices, looked at how often residents of different neighborhoods filled prescriptions for different categories of drugs.

Patients in wealthier neighborhoods were much more likely to pick up prescriptions for lifestyle problems: erectile dysfunction, baldness, anti-wrinkle Botox injections and an eye medicine that thickens eyelashes. This may be unsurprising.

But the analysis also showed that richer patients were more likely to buy drugs for certain serious conditions, including mental health disorders. This was the case even though the analysis showed that income doesn’t track with overall prescription use.

These prescriptions for serious conditions were filled disproportionately in rich neighborhoods despite evidence that the rich tend to be in overall better health. In fact, people in rich neighborhoods filled fewer prescriptions than people in middle-class neighborhoods. The blend of data suggests that, while prescriptions and income don’t track well over all, there are points where they do.

The relationship between income and prescription drug purchasing is more complicated than whether someone has money to spend at the pharmacy. Depending on income and life circumstances, Americans may have different odds of developing certain illnesses and of seeking treatment — even before the direct cost of medicines becomes an issue.

“There are definitely a bunch of financial barriers before you even get to the point of getting to fill a drug,” said Stacie B. Dusetzina, an associate professor of health policy at Vanderbilt University. She said social and cultural factors could matter, too: Evidence has shown that doctors are less likely to prescribe pain medicines to black patients than white ones, for example.

Niteesh Choudhry, a professor of medicine and public health at Harvard, said that his research hadn’t shown a clear relationship between income and prescription drug use. Instead, he said, cultural and racial factors — and the details of insurance coverage — were better predictors. When it comes to treatments for very common conditions, “the income relationships are probably not linear,” he said.

Several experts in the demographics of drug use said all those factors might explain the higher usage of medications for mental health problems among wealthier people. Some mental health problems are more prevalent among Americans with lower incomes, evidence shows. But longtime holes in the health care system mean that richer patients are more likely to have private insurance or extra money to pay for psychiatric care that is not covered by insurance. And some people in lower-income communities may feel more stigma around mental health diagnoses.

A similar dynamic could explain lower prescription rates for birth control among lower-income women. Under Obamacare, all women with health insurance should be able to get contraception with no co-payment. So cost at the pharmacy counter can’t alone explain the differences. But higher-income women may be more likely to have a regular doctor to prescribe pills. (The data shows that emergency contraceptive purchases, also available without co-payment, were more common in lower-income neighborhoods.)

The high cost of EpiPens alone may explain some of the differences in usage. Current guidance is for patients to stock several of the devices, used to treat life-threatening allergic reactions, and replace them often. But their high cost may lead some poorer patients to make do with fewer or older ones, while those with more disposable income might stock extras.

Some drugs seem to be taken about equally regardless of income. The use of antibiotics appears to be roughly the same for middle-class and rich Americans. These drugs are used for some serious diseases, have few over-the-counter substitutes, and tend to be inexpensive.

Some drugs are much more commonly used at the low end of the income scale. Consider treatments for hepatitis C and H.I.V. These are diseases that disproportionately affect low-income Americans, and that pattern is reflected in the prescription purchasing patterns.

The GoodRx data looked at a sample of 53 million retail pharmacy purchases in 39 large metropolitan areas over a year ending in October 2018, then divided them according to the income characteristics of the people who lived in the census tract where the pharmacy was located.

This is not exactly the same as tracking individual customers by income, but most people buy drugs at pharmacies near their homes. The data includes drug purchases by people with both public and private health insurance, and by some customers who buy their medications using cash. Analysts at GoodRx then grouped drugs prescribed for various diagnoses to build categories. They also made some adjustments to the data in cases where the sample overrepresented one kind of insurance.