Potential Misuse and Inappropriate Prescription Practices Involving Opioid Analgesics | Page 2
Published Online: August 12, 2013
Ying Liu, PhD; Joseph E. Logan, PhD; Leonard J. Paulozzi, MD, MPH; Kun Zhang, MS; and Christopher M. Jones, PharmD
At the enrollee level, indicators of opioid general use included the total number of opioid prescriptions obtained, total days of supply, and medical diagnoses (eg, acute pain, chronic pain, or both) associated with opioid prescriptions. Acute pain and chronic pain diagnoses were based on ICD-9-CM codes (Table 2, footnotes b and c). Benzodiazepine and muscle relaxant use in combination with opioids was also examined. Indicators of potential misuse or inappropriate prescription practices consisted of (1) opioid overlap, defined as opioid prescriptions that overlap by 7 or more days (including early refills); (2) opioid and benzodiazepine overlap, defined as opioid and benzodiazepine prescriptions that overlap by 7 or more days; (3) long acting/extended release (LA/ER) opioid prescriptions written for acute pain conditions; (4) high daily opioid dosage, defined as a prescribed daily dose of 100 morphine milligram equivalents (MMEs) or greater (MME conversion factors are provided in Table 1); and (5) opioid dose escalation, measured as having a 50% or greater increase in mean MMEs per month twice consecutively during the year.
At the prescription level, indicators of opioid general use included the number of days of supply and the prescribed daily doses for opioid prescriptions for acute, chronic, and back pain. Back pain included both acute and chronic back pain and was based on ICD-9-CM codes recommended by the American College of Occupational and Environmental Medicine practice guidelines.20 Indicators of potential misuse or inappropriate prescription practices included the proportion of opioid prescriptions involved in opioid overlap or opioid and benzodiazepine overlap, similar to the enrolleelevel analysis, and 3 indicators specific to LA/ER prescriptions given their elevated risk for addiction and abuse: (1) overlapping LA/ER opioid prescriptions; (2) LA/ER prescriptions written for acute pain; and (3) LA/ER prescriptions obtained by an opioid-naïve person, defined as a person who had no use of an opioid for at least 60 days prior to LA/ER drug initiation.
We calculated the distributions of various levels of usage among all enrollees receiving an opioid prescription overall, by sex, and by pain type. The prevalences of indicators of potential misuse by patients or inappropriate prescription practices by providers were calculated as both percentages of enrollees and percentages of prescriptions. We used x2 tests for comparisons by sex. Because of the large sample sizes, differences by sex might have been statistically significant (P <.05) but not clinically meaningful. Therefore, we only provide test results for sex differences that were considered meaningful.
Among the overall study population of opioid recipients, 59% were female (Table 2). The mean age of opioid recipients was 44.7 years among males and 43.2 years among females. Males and females received comparable amount of opioids, as measured by the number of prescriptions and total days of supply received per person in 2009. More than half of all recipients had only 1 opioid prescription; fewer than one-third of recipients (28.3%) had 3 or more opioid prescriptions. Notably, 2.3% of enrollees had 20 or more opioid prescriptions during the data year—with nearly 0.1% of enrollees receiving 50 or more opioid prescriptions (data not shown).
More than three-fourths of the recipients (78.5%) received fewer than 30 days of supply of opioids; about 12% of recipients received more than 90 days of supply of opioids. Among all opioid recipients, 16.3% also filled a benzodiazepine prescription during the data year, and 10.3% filled 2 or more such prescriptions. A higher proportion of females than males received both an opioid and benzodiazepine (19.0% vs 12.5%; P <.05).
We were able to identify the underlying medical diagnoses for opioid prescriptions for 82.3% of the overall study population. About 27.9% of the recipients obtained opioids for acute pain conditions only; 13.7% received opioids for chronic pain conditions only; and 24.2% obtained opioids for both acute and chronic pain conditions. Another 17.7% of the recipients received opioid prescriptions for diagnoses not included in the lists of acute or chronic pain conditions. Nearly a quarter of opioid recipients showed at least 1 indicator (Table 3). The most common indicator was having high daily doses; an estimated 15.0% of the study population had daily doses of 100 MMEs of higher. The prevalence of opioid overlap and opioid and benzodiazepine overlap was 7.8% and 8.0%, respectively. About 0.9% of enrollees received LA/ER opioids for acute pain, and 1.2% had opioid dose escalation. A higher percentage of females versus males (9.1% vs 6.3%; P <.01) had 1 or more incidents of opioid and benzodiazepine overlap. A higher percentage of females versus males also had 1 or more incidents of high daily dose of opioids (16.2% vs 13.2%; P <.01). Overall, females were more likely than males to have any type of indicator (26.7% vs 22.4%; P <.05).
Among the 7,714,067 prescriptions that were linked to diagnoses, about a quarter of them were written for acute pain conditions. A slightly higher proportion (28.8%) were for chronic pain, and 15.6% were associated with both acute and chronic pain (Table 4). The remaining 30.2% of the prscriptions were linked to diagnoses not included in the lists of acute or chronic pain conditions. In addition, about 6.9% of the opioid prescriptions were written for either acute or chronic back pain conditions.
The median days of supply for acute pain, chronic pain, and back pain were 5, 15, and 20 days, respectively. For acute pain, 22.8% of prescriptions were written for 10 or more days, and 9.5% were written for 30 or more days. For chronic pain, more than one-third of the prescriptions were for 30 or more days. The duration distribution for back pain, whether acute or chronic, was similar to that for chronic pain. The distributions for the days of supply for acute pain, chronic pain, and back pain were similar for males and females.
The median daily opioid dose for prescriptions for acute pain was similar for both sexes at 40 MME. The median daily dose for opioid prescriptions for chronic pain was higher for males (40.0 MME) than for females (37.5 MME). Among both acute pain and chronic pain prescriptions, 11.8% to 14.0% had a daily dose of 100 MME or greater; 1.9% to 4.5% of prescriptions were for 200 MME or greater.
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