The Contribution of Obesity to Prescription Opioid Use in the United States

Andrew Stokes; Kaitlyn M. Berry; Jason M. Collins; Chia-Wen Hsiao; Jason R. Waggoner; Stephen S. Johnston; Eric M. Ammann; Robin F. Scamuffa; Sonia Lee; Dielle J. Lundberg; Daniel H. Solomon; David T. Felson; Tuhina Neogi; JoAnn E. Manson

Disclosures

Pain. 2019;160(10):2255-2262. 

In This Article

Abstract and Introduction

Abstract

The prevalence of obesity has grown rapidly over the past several decades and has been accompanied by an increase in the prevalence of chronic pain and prescription opioid use. Obesity, through its association with pain, may represent an important contributor to opioid use. This cross-sectional study investigated the relationship between obesity and prescription opioid use among adults aged 35 to 79 years using data from the National Health and Nutrition Examination Survey (NHANES, 2003–2016). Relative to normal weight, body mass indices in the overweight {odds ratio (OR), 1.11 (confidence interval [CI], 0.88–1.39)}, obese I (OR, 1.26 [CI, 1.01–1.57]), obese II (OR, 1.69 [CI, 1.34–2.12]), and obese III (OR, 2.33 [CI, 1.76–3.08]) categories were associated with elevated odds of prescription opioid use. The association between excess weight and opioid use was stronger for chronic opioid use than for use with a duration of less than 90 days (P-value, <0.001). We estimated that 14% (CI, 9%-19%) of prescription opioid use at the population level was attributable to obesity, suggesting there might have been 1.5 million fewer opioid users per year under the hypothetical scenario where obese individuals were instead nonobese (CI, 0.9–2.0 million users). Back pain, joint pain, and muscle/nerve pain accounted for the largest differences in self-reported reasons for prescription opioid use across obesity status. Although interpretation is limited by the cross-sectional nature of the associations, our findings suggest that the obesity epidemic may be partially responsible for the high prevalence of prescription opioid use in the United States.

Introduction

The prevalence of obesity has grown rapidly over several decades, with the proportion of U.S. adults with obesity increasing from 15% in 1976–1980 to 40% in 2015–2016.[23] Obesity is associated with heightened risk of diabetes, cardiovascular disease, and cancer, and is responsible for an estimated 380,000 deaths annually.[32] The increase in obesity has been accompanied by a rise in the prevalence of chronic pain. Between 1998 and 2014, the proportion of U.S. adults reporting pain increased from 21.4% to 34.9% among men and 30.4% to 41.5% among women.[54] In 2015, 25.3 million adults (11.2%) reported experiencing chronic daily pain.[34]

A report from the Institute of Medicine identified obesity as one of 5 major contributors to chronic pain.[26] Obesity raises risks of numerous conditions associated with chronic pain, including osteoarthritis,[3] low back pain,[46,47] diabetes-associated neuropathy,[38] fibromyalgia,[50] and migraine.[5,41] This increased risk may be explained by several factors, including biomechanical strain on joints and stimulation of a systemic inflammatory state.[43,49] Recent estimates indicate that low back pain and osteoarthritis are among the leading causes of years lived with disability in the United States.[32] Obesity may also be associated with lower pain tolerance because weight loss has been shown to improve pain sensitization.[48]

Dramatic increases in prescription opioid use have also occurred in recent years.[1,19] Previously limited primarily to settings of end-of-life care, postsurgical care, and acute pain, prescription opioids have been increasingly used for chronic pain, with use rates quadrupling between 1999 and 2010.[12] The trend towards use of prescription opioids in chronic pain management has also contributed to rising levels of opioid dependence and overdose deaths.[13] Prescription opioid dependence affected 2 million people and contributed to over 15,000 U.S. overdose deaths in 2015.[19]

Explanations for the opioid crisis have focused primarily on the role of supply-side factors, including shifts in pain assessment and treatment norms,[6,29] insurers reducing coverage for behavioral pain therapy, and pharmaceutical innovation and marketing.[20,21,29,52] Although the role of supply-side factors is well established, the underlying causes of demand for opioids are less clear. Some prior research has attributed the opioid crisis to increasing economic and social dislocation or to deteriorating mental health.[7,8,17] Another possibility that has received less attention is that obesity has increased demand for prescription opioids through its complex associations with disability and pain.[10]

This study investigates this latter possibility using recent data from a nationally representative sample of the U.S. adult population. In our primary analysis, we examine the association of obesity with prescription opioid use and estimate the percentage of prescription opioid use attributable to obesity at the population level. Because long-term opioid therapy and stronger opioid regimens are associated with increased risks of opioid dependence and overdose,[4,14,45] we additionally investigate the association of obesity with duration and strength of opioid use. Finally, we examine individuals' self-reported reasons for opioid use to identify the major types of pain underlying the differences in prescription opioid use by obesity status.

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