The five studies reviewed focused on three different patient populations.[27–31] The earliest studies initially focused on specific chronic pain populations that are prevalent in the USA. One population analyzed patients that had OA and the second population analyzed patients that had cLBP. People with these types of pain are not uncommon, with one in four adults over the age of 65 years worldwide being affected by OA, whereas cLBP pain is the most common type of pain that people currently have and approximately 80% of people will experience some form in their lifetime. The third population analyzed encompassed all types of chronic pain patients, excluding those related to pregnancy and cancer pain, in order to determine if the prevalence of DDEs and their economic impact was isolated to specific pain populations or if it is a more widespread general problem in the chronic pain patient. Analysis of the precipitant drugs and their association with increased health care costs was not conducted in any of the five studies.
These pain populations are well suited for studying DDIs because of their increased risk to experiencing DDEs based on their current medication regimen. Many of these patients are prescribed opioids to mitigate their pain, which has been recommended by The American Pain Society and the American Academy of Pain. Some of these consumed opioids are metabolized through the CYP450 system, and thus patients in these chronic pain populations are at increased risk for experiencing DDEs when additional CYP450 metabolized medications are taken. In fact, patients on opioids, especially older adults (>65 years) have been documented to be more likely to be taking additional prescription medications, thus exposing themselves to possible DDIs. All of these factors thus make the chronic pain patient population suitable for DDI analysis.
These studies used the Truven Health Market Scan® research databases that include person-specific data on health care utilization, expenditures and enrollments across inpatient, outpatient and prescription drug claims. For the commercially insured ''younger' population (18–64 years), medical and pharmacy claims data from the Commercial databases were utilized. Medicare Supplemental and Coordinator of Benefits databases were used to obtain similar patient-specific data for 'older' patients 65 years of age and older. The source of databases included more than 100 large employers, health plans and public organizations. Patients who were on a CYP450 metabolized opioid or 'index opioid' (codeine, fentanyl, hydrocodone, methadone, oxycodone and tramadol) were used in all studies.
Expert Rev Pharmacoeconomics Outcomes Res. 2013;13(6):725-734. © 2013 Expert Reviews Ltd.