Opioid Medication Practices Observed in Chronic Pain Patients Presenting for All-Causes to Emergency Departments: Prevalence and Impact on Health Care Outcomes

BACKGROUND: Chronic pain is a significant health problem that affects an estimated 100 million American adults (aged ≥ 18 years). Chronic pain affects more individuals than heart disease, stroke, diabetes, and cancer combined. Chronic pain sufferers cost up to $635 billion annually in medical treatment and lost productivity. Opioids are commonly used to treat chronic pain, but their metabolic interactions with concurrently prescribed medications for concomitant disease burdens can affect potency and efficacy of pain therapy. Additionally, misuse of short-acting opioids (SAOs) for chronic pain versus breakthrough pain can create gaps in pain relief. These potentially suboptimal prescribing practices may contribute to the high economic impact associated with chronic pain. OBJECTIVE: To examine the prevalence of suboptimal opioid therapy and the associated health care costs resulting from these prescribing practices in real-world patients presenting for all-causes to the emergency department (ED). METHODS: This retrospective observational database cohort analysis used the linked Premier-Optum database and included patients with ED visits from 2006 to 2010 having ≥60 days supply of opioids in the 75 days prior to the visit. Suboptimal prescribing practices were identified as patients with (a) drug-drug exposures (DDEs), defined as cytochrome P-450 (CYP-450)-metabolized opioids prescribed concurrently with CYP-450 inhibitors or inducers and/or (b) monotherapy with SAOs. Comorbid conditions and principal diagnoses were documented. Readmission rates to the ED and hospital within 72 hours as well as ≤ 30, ≤ 45, ≤60, and ≤ 90 days were computed. Total costs for health care were calculated, and reimbursement rates were normalized using 2011 Medicare severity diagnosis-related group (MS-DRG) and CPT-4 information. Nonparametric bootstrapping to adjust for patient comorbidities was applied to cost data. RESULTS: Of the 9,214 patients identified with chronic pain, potentially suboptimal medication practices prior to the index ED visit were found for 8,539 (92.6%) patients. These appeared to be corrected in 345 (4.0%) patients before leaving the ED. Of 675 (7.3%) patients without prior DDE or exclusive use of SAOs, 345 (51.1%) patients were discharged with one of these. Of the 8,352 patients who left the ED with DDE or exclusive use of SAOs, 1,525 (18.3%) left with a DDE without exclusive SAO use; 4,812 (57.6%) left with both DDE and exclusive SAO use; and 2,015 (24.1%) left with only exclusive SAO use. Only 862 (9.3%) patients from the entire cohort left the ED without DDE or exclusive SAO use. Patients identified with suboptimal opioid use were aged 50 ± 13.5 years and were predominantly female (64.0%). Hypertension (44.0%), fluid and electrolyte disorders (32.7%), chronic pulmonary disease (22.8%), depression (19.6%), diabetes without chronic complications (16.2%), and drug abuse (15.6%) were the most prevalent comorbid conditions identified. The most prevalent principal diagnoses involved symptoms and signs of ill-defined conditions (36.5%), injury and poisoning (18.2%), and diseases of the musculoskeletal system (13.2%). The majority of revisits to the ED and hospital admissions occurred within 72 hours (73.6%) of the index visit and within 30 days (70%), respectively. When adjusted total costs were compared for all patients whose opioid use included DDE versus those without, a significantly greater cost (P < 0.05) was observed at every time period except ≤ 72 hours. Respective mean increases in costs were $581, $689, $773, and $1,275 at 30, 45, 60, and 90 days. Exclusive SAO use with or without DDE resulted in a significant increase (P < 0.05) in mean costs at all times: $214 at 72 hours; $836 at 30 days; $1,023 at 45 days; $1,022 at 60 days; and $1,536 at 90 days. CONCLUSIONS: This study identified potentially suboptimal opioid prescribing practices in a real-world population presenting for all-causes to the ED. The observed rate of ED revisits and inpatient admissions in these patients was associated with increased health care costs. These findings suggest that the ED has the future potential to serve as an ideal setting to identify and correct such practices, thereby improving patient care and reducing resource use and beneficiary costs.