Only half of the pharmacies in non-white areas that were surveyed by a University of Michigan team had even a scant supply of the kinds of drugs used to treat severe chronic pain, such as back and joint aches. That's much lower than the percentage of pharmacies in mostly white areas, where more than 90 percent of pharmacies had the drugs in stock.
Overall, retail chain pharmacies were less likely than independent pharmacies to carry a sufficient stock of the drugs, known as opioid painkillers. And pharmacies in wealthier ZIP codes of any racial makeup tended to have a better supply.
The study, conducted by a pain research team from the U-M Health System, will be presented here on May 7 at the annual meeting of the American Pain Society.
While the researchers didn't delve deeply into the reasons behind the discrepancies they found, previous research has suggested that pharmacies in poorer or higher-crime areas do not stock opioid drugs because of the real or perceived threat of robbery. In addition to their medically useful painkilling properties, many of the drugs have a street value.
The new results echo findings from New York City that were published by a Columbia University team several years ago. But the U-M authors note that their survey covered an entire state, and looked at more drugs: a total of 15, in three categories. If a pharmacy had even one bottle of one drug from each category, it was considered to have an adequate supply.
Half of the pharmacies were in ZIP codes whose population was more than 70 percent non-white, and the other half were randomly sampled from ZIP codes around the state whose populations were more than 70 percent white.
"The key thing we found is that there are differences in availability of medications. If you are a person living in Detroit and you can't walk to the store to get the medications you need to reduce your pain and help you function, this can be a big problem," says Carmen R. Green, M.D., the U-M pain specialist who led the study.
Green launched the study after hearing from a patient who couldn't find a pharmacy in her mostly African-American neighborhood where she could fill a prescription that Green had given her to treat chronic pain. She had to go to a pharmacy in the suburbs to get the pain medication prescription filled.
Green sees patients with all types of pain at the U-M Center for Interventional Pain Medicine, and studies issues affecting them as head of the Michigan Pain Outcomes Study Team. An associate professor of anesthesiology at the U-M Medical School, she has specialized in studying topics relating to race, age and chronic pain, and chairs the American Pain Society's special interest group on Pain and Disparities in Pain Management.
The study she will describe at the APS meeting used data from the 2000 Census, including race, median age and median income by ZIP code. While the researchers did not find an influence on medication availability based on median age, the association with race was strong – and there was an interaction between race and income when both variables were considered together.
Green's team telephoned the 190 pharmacies and asked them about their stocks of medications in three categories: long-acting opioid painkillers, short-acting ones, and combination products that include an opioid and a non-opioid drug.
Pharmacies had to have at least one drug from each category to be considered as having an adequate supply, though Green notes that it would be better to have several choices in order to fill a doctor's exact orders. In all, 71 percent of the pharmacies had an adequate supply of opioids using this definition.
Examples of long-acting opioids include controlled-release oxycodone, often sold as Oxycontin, and controlled-release morphine. Short-acting opioids include meperidine (sold as Demerol), hydromorphone (sold as dilaudid) and immediate-release oxycodone. And combination products included hydrocodone/acetaminophen (sold as Vicodin and Lorcet), and acetaminophen/oxycodone (known as Percocet or Tylox).
"All of these medications, when used appropriately, have tremendous potential to help patients overcome chronic pain that interferes with their ability to work and carry out daily activities," says Green. "But they also carry an addictive and high-inducing potential that makes them attractive on the black market. While we can't say that fear of theft is behind the discrepancy in availability, we know that some of the pharmacists we spoke with admitted this was a factor. However, most pharmacists surveyed said they didn't get much demand for these medicines, which suggests that we need to look at prescription patterns and other factors."
When the researchers looked at individual medications, significant differences between pharmacies in white and non-white areas arose in four of the five long-acting opioids, all five of the short-acting opioids, and two of the five combination products.
When they looked at median income combined with race, there was an interaction between the two factors.
The median income for all the ZIP codes surveyed was $39,322. Among pharmacies in areas below that median, pharmacies in minority ZIP codes were about 16 times less likely to have a sufficient opioid supply than those in white ZIP codes. But among all ZIP codes with a median income at or above that amount, pharmacies in minority ZIP codes were only 4.6 times less likely to have a sufficient opioid supply. However, Green cautions, the sample size is too small to draw many conclusions about this interaction. "We need to examine this issue further," she explains.
"The bottom line is, if a pharmacy doesn't stock a certain medication, a person in pain may end up in a situation where their physician will prescribe pain medication, but the patient can't get the prescription filled," Green concludes. "Given the incredible impact on daily function, quality of life and economic output that chronic pain can have, this is a crucial issue for physicians and health care providers to be sensitive to, when treating patients who live in areas with large minority populations."
In addition to Green, the study was conducted by Carla Talarico, Tamika Washington and S. Khady Ndao-Brumblay. Three members of the team, Andrea Black, Cecelia Calhoun, and Kyungmin Kang, participate in the U-M's Undergraduate Research Opportunity Program.