Economic study on the impact of side effects in patients taking oxycodone controlled-release for noncancer pain.

BACKGROUND: Chronic pain is a prevalent condition in the United States. Musculoskeletal pain, including joint and back pain, is the most common type of chronic pain, and many patients with back pain have a neuropathic component. Pain has direct economic consequences. While oxycodone controlled-release (CR) is one of the most widely used oral long-acting opioids for pain, including pain with a neuropathic component, it is often associated with bothersome side effects, resulting in additional medical resource use (MRU) and costs.

OBJECTIVE: To examine the impact on MRU and costs to payers of side effects in patients taking oxycodone CR alone or in combination with other pain medications for noncancer pain (including those with neuropathic pain symptoms).

METHODS: A nationwide convenience sample of adults in the United States, who participated in a survey research panel and reported current use of oxycodone CR for noncancer pain, completed an online survey between November 2, 2010, and December 13, 2010. Respondents were excluded if they reported current use of other extended-release or long-acting opioid prescription medications. The survey consisted of questions on demographics, clinical characteristics, pain characteristics, experience with pain medication, and MRU associated with side effects. Payer costs were calculated based on the MRU reported by the respondents multiplied by Medicare reimbursement rates for hospitalizations and outpatient visits and average wholesale price (AWP) minus 20% for medications. A subgroup of patients who reported neuropathic pain symptoms also was examined.

RESULTS: After applying the exclusion criteria, 432 respondents completed the survey. Approximately half of the respondents (n = 219; 50.7%) reported neuropathic pain symptoms. The majority of respondents were Caucasian (88.4%) and female (63.7%) with an average age of 41.8 years (14.89). Respondents most frequently reported low back pain (41.2%), followed by osteoarthritis/rheumatoid arthritis (20.4%), neuropathic pain (10.6%), and fibromyalgia (9.0%). Respondents reported having their pain condition for an average of 5.4 (7.42) years. On days when taken, respondents reported a mean oxycodone CR daily dose of 83.3 mg (126.93) taken in an average of 2 doses. Most respondents (82.4%) reported experiencing at least 1 side effect with 77.5% being bothered by at least 1 side effect. The most frequently reported side effects ( greater than 25%) were drowsiness (41.4%), constipation (37.0%), fatigue or daytime sleepiness (36.6%), and dizziness (27.1%). Among respondents who reported being bothered by one or more side effects in the previous month, MRU associated with side effects was reported by 39.1% of respondents and significantly increased as the level of side-effect bother increased from 19.8% among those "A little bit bothered" to 38.4% among those "Bothered" to 61.0% among those "Extremely bothered" (P less than 0.001). Additionally, total average payer costs (in 2010 dollars) per respondent in the previous month associated with side effects were $238 ($1,159) and also significantly increased as the level of side-effect bother increased from $61 ($512) among those "A little bit bothered" to $238 ($1,160) among those "Bothered" to $425 ($1,561) among those "Extremely bothered" (P less than 0.001). Results reported in the neuropathic pain subgroup were similar to results reported in the total study sample.

CONCLUSIONS: Among adults taking oxycodone CR for chronic noncancer pain (with or without a neuropathic pain component), over three-fourths reported being bothered by side effects. Respondents who reported higher levels of side-effect bother also reported greater MRU, resulting in increased payer costs. The results of this study provide further support of the econo-mic burden to payers associated with opioid-related side effects in patients with chronic noncancer pain, with and without neuropathic pain.