Obesity increases medical treatment costs by over $3,500 per person each year. A new study suggests there may be an even greater cost — both financial and human — related to obesity: excess opioid prescribing and all the risks that come with it. A team of Boston University researchers used de-identified athenahealth data from electronic health records to analyze the link between obesity and opioid prescribing. Their findings revealed a pattern of obesity-related chronic pain conditions that led to opioid prescribing far above that for the rest of the population.

Patients came from diverse backgrounds, locations, and age groups

The study looked at the patient records of 565,930 adults aged 35 to 64 who were seen by a primary care physician between January 2015 and December 2017 and had a Body Mass Index (BMI) measurement in their chart. At the time they were seen, 31 percent of these patients were overweight, and 48 percent were obese.

In total, 93,954 were prescribed opioids within 365 days of a primary care visit. Researchers compared the prescribing rates of normal weight, overweight, and obese (classes I, II, III, and IV) patients. Based on how the claims were coded, researchers identified the most common conditions resulting in opioid prescriptions and compared the prescription rates for normal weight and overweight or obese patients.

The data set included patients from all across the U.S. in both rural and urban locations. Patients represented multiple race and ethnicity categories as well as a full range of insurance coverage (commercial, Medicare, and Medicaid).

More precise and comprehensive data allow deeper insights

What distinguished this study was the ability to not only correlate opioid prescribing with obesity, but also dig deep into the specific conditions that are most likely to lead to excessive opioid prescribing in patients who are obese.

The athenahealth data set made it possible for researchers to examine 26 different pain diagnoses by obesity status based on the ICD-10 codes available in the data — everything from arthritis to back pain to myopathy. Creation of the data set used in this study was made possible through a partnership between Boston University, athenahealth, and the Robert Wood Johnson Foundation.

“Perhaps it would be possible to establish an association of obesity with prescribing in other data sets,” says Andrew Stokes, Ph.D., assistant professor of global health at Boston University School of Public Health and lead investigator on the study, “but we wouldn’t have the granularity, the ability to look at all these different pathways.” And it is that granularity provided by the athenahealth dataset that Stokes believes allows these findings to have a greater practical impact on patient treatment.

Study finds link between obesity and opioid prescribing across all ages and backgrounds

The data clearly show that being overweight or obese increases a patient’s chance of being prescribed opioids, and that risk increases progressively with BMI. In other words, the greater the BMI, the greater the chance of receiving an opioid prescription. At the broader population level, the study estimated that 16.2 percent of opioid prescriptions were attributable to the patient being overweight or obese. Patients in the obese III category had a 48 percent increased risk of receiving prescription opioids and patients in the obese IV category had a 71 percent increased risk.

Among patients with obesity, three pain diagnoses were most commonly associated with opioid prescribing across all age groups, ethnicities, regions, and insurance types: other back disorders, other joint disorders, and osteoarthritis. These conditions accounted for 53.4 percent of the absolute difference in prescribing associated with obesity. Not surprising, obesity is a known risk factor for both osteoarthritis and back disorders.

The association between BMI and opioid prescribing was stronger for women than men and stronger in the Northeast than in other regions. The link was also stronger in urban areas than in rural locations.

Changes in chronic pain and obesity management could improve opioid epidemic

According to the study’s authors, these results suggest more attention should be paid to the prevention and management of this set of chronic conditions without reliance on opioids for pain management, focusing on non-opioid medications as well as non-pharmacological approaches like physical therapy, cognitive behavioral therapy, and acupuncture.

“A lot of policy and programs have focused on reducing the supply of opioids,” says Stokes, “but if we don’t effectively prevent and manage pain — chronic pain in particular — the need will still be out there.” His hope is that this research will create greater awareness throughout the public health community of how obesity, through its association with chronic pain, has played a significant role in the increased demand for prescription opioids.

The study results also suggest that more should be done to focus on obesity prevention and treatment, with such offerings as counseling on physical activity and nutrition, medications for weight loss, and even weight-loss surgery. According to Stokes, “these interventions could have the immediate benefit of improving people's weight and lifestyles, but it might also have the additional consequence of helping to reduce pain severity and opioid prescribing and use.”

The opioid epidemic gets a lot of attention from media and from policymakers. This study suggests that policies to prevent opioid use should consider population-based obesity-prevention efforts like nutritional labeling, targeted taxes or subsidies, regulation of nutrition in school cafeterias, programs to increase the availability and affordability of healthy foods, and so much more.

“In a way,” says Stokes, “food policy and policies related to physical activity and health behaviors are opioid policy.”

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Lia Novotny is a contributing editor to athenahealth's Knowledge Hub.