title: Cost of pain medication to treat adult patients with nonmalignant chronic pain in the United States.
abstract: BACKGROUND
  Nonmalignant chronic pain (NMCP) is a public health concern. Among primary care appointments, 22% focus on pain management. The American Academy of Pain Medicine guidelines for NMCP recommend combination medication therapy (including analgesics, nonsteroidal anti-inflammatory drugs [NSAIDs], opioids, antidepressants, and anticonvulsants) as a key component to effective treatment for many chronic pain diagnoses. However, there has been little evidence outlining the costs of pain medications in adult patients with NMCP in the United States, an area that necessitates further consideration as the nation moves toward value-based benefit design.
  
  
  OBJECTIVE
  To estimate the cost of pain medication attributable to treating adult patients with NMCP in the United States and to analyze the trend of outpatient pain visits.
  
  
  METHODS
  This cross-sectional study used the National Ambulatory Medical Care Survey (NAMCS) data from 2000-2007. The Division of Health Care Statistics, National Center for Health Statistics, and the Centers for Disease Control and Prevention conducted the survey. The study included patients aged ≥18 years with chronic pain diagnoses (identified by the ICD-9-CM codes: primary, secondary, and tertiary). Patients prescribed at least 1 pain medication were included in the cost analysis. Pain-related prescription medications prescribed during ambulatory care visits were retrieved by using NAMCS drug codes/National Drug Code numbers. National pain prescription frequencies (weighted) were obtained from NAMCS data, using the statistical software STATA. We created pain therapy categories (drug classes) for cost analysis based on national pain guidelines. Drug classes used in this analysis were opioids/opioid-like agents, analgesics/NSAIDs, tricyclic antidepressants, selective serotonin reuptake inhibitors, antirheumatics/immunologics, muscle relaxants, topical products, and corticosteroids. We calculated average prices based on the 3 lowest average wholesale prices reported in the Red Book 2009 for maximum recommended daily dose. Total pain medication costs were calculated in 2009 and 2013 dollar values. The study analyzed NMCP-related outpatient visit trends and used time series analysis to forecast visits using U.S. population data and statistics.
  
  
  RESULTS
  The total costs of prescription medications prescribed for pain were $17.8 billion annually in the United States. Cost estimates were captured based on a total of 690,205,290 (~690 million) weighted outpatient visits made for chronic pain from 2000 to 2007 in the United States. Of those patients, 99% received a medication that could be used for NMCP. Among the patients, 29% reported taking ≥5 medications. A linear trend of pain visits is visible, reporting change (from 11% to 14%) from 2000 to 2007 in the United States. All agents except opioids/opioid-like agents and analgesics/NSAIDs were further categorized as adjuvant therapy to create 3 major drug class categories. The largest 3 categories of pain therapy for the United States (annually) were analgesics/NSAIDs ($1.9 billion), opioids ($3.6 billion), and adjuvants ($12.3 billion). Despite having the highest prescription frequency nationally, analgesics/NSAIDS accounted for about 11% of the overall pain medication costs. This study found that adjuvant therapy accounted for 69% of the total pain medication costs. Among adjuvants, 33.5% of the cost was contributed by antirheumatics/immunologics. Other adjuvants included muscle relaxants (4.4%), topical products (8.6%), and corticosteroids (9.4%).
  
  
  CONCLUSIONS
  This study demonstrated national prescribing costs and use within various drug categories of pain medications in a large outpatient population over an 8-year period in the United States. Policymakers, stakeholders, and health plan decision makers may consider this cost analysis, since they need to know how drug costs are being allocated. Moreover, information about costs and use of pain medications is valuable for the practitioner making individual patient care decisions, as well as for those who make population based decisions. This study reported an increasing trend of outpatient pain visits in the United States. Therefore, policymakers and health plan decision makers may expect a growing number of pain-related outpatient visits in coming years and allocate resources accordingly to meet the need.
authors.affiliation: University of Missouri-Kansas City School of Pharmacy, Kansas City, MO 64108. rasur@umkc.edu.
authors.forename: Rafia S
authors.initials: RS
authors.lastname: Rasu
authors.forename: Kiengkham
authors.initials: K
authors.lastname: Vouthy
authors.forename: Ashley N
authors.initials: AN
authors.lastname: Crowl
authors.forename: Anne E
authors.initials: AE
authors.lastname: Stegeman
authors.forename: Bithia
authors.initials: B
authors.lastname: Fikru
authors.forename: Walter Agbor
authors.initials: WA
authors.lastname: Bawa
authors.forename: Maureen E
authors.initials: ME
authors.lastname: Knell
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000700:Analgesics / Q000191:economics* / Q000627:therapeutic use*; D000701:Analgesics, Opioid / Q000191:economics / Q000627:therapeutic use; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000191:economics / Q000627:therapeutic use; D059350:Chronic Pain / Q000188:drug therapy* / Q000191:economics; D003365:Costs and Cost Analysis; D003430:Cross-Sectional Studies; D016527:Drug Costs; D011307:Drug Prescriptions; D004359:Drug Therapy, Combination / Q000191:economics; D005260:Female; D019538:Health Care Surveys; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D008875:Middle Aged; D010818:Practice Patterns, Physicians'; D014481:United States; D055815:Young Adult
chemical_list: D000700:Analgesics; D000701:Analgesics, Opioid; D000894:Anti-Inflammatory Agents, Non-Steroidal