Economic impact of potential drug-drug interactions among osteoarthritis patients taking opioids.

Patients with osteoarthritis (OA) taking at least one CYP450-metabolized opioid concurrently with another CYP450-metabolized medication experience a drug-drug exposure (DDE), which puts them at risk of a pharmacokinetic drug-drug interaction (PK DDI). This study compared patients with and without such an incident DDE to determine healthcare utilization and associated payments. Using a retrospective database analysis, the impact of DDEs was evaluated in terms of associated clinical events, healthcare services utilization (office visits, outpatient visits, ED visits, hospitalization), and payments in patient populations based on age (those under age 65 and those 65 years of age and older), during the 6 months after exposure. DDE patients had significantly more inpatient hospitalizations than no-DDE patients. Mean total payments at 6 months were significantly higher for both younger and older patients with DDE compared to similar patients without DDE ($9,469, SD = $12,192 vs. $8,382, SD = $14,078, respectively, for younger patients, resulting in a difference of $1,087, P < 0.004, and $9,829, SD = $11,721 vs. $8,622, SD = $10,131, respectively, for older patients, resulting in a difference of $1,207, P = 0.001). In both age groups, DDE patients had significantly higher payments for nonopioid prescription drugs ($1,824 SD = $2,420 vs. $1,362, SD = $1,891, respectively, for younger patients, resulting in a difference of $462, P < 0.001, and $2,197 SD = $2,332 vs. $2,013, SD = $2,437, respectively, for older patients, resulting in a difference of $184, P = 0.020). Overall, patients with OA who experienced DDEs had significantly greater utilization rates of healthcare resources and higher associated payments in the 6-month observation period following the exposure, compared to patients without DDEs, consistent with the risk of PK DDIs associated with DDEs.

A Comparison of Daily Average Consumption Of Oxycodone Controlled Release (OxyContin CR) And Oxymorphone Extended Release (Opana ER) In Patients With Low Back Pain.

OBJECTIVE: Our goal was to examine the daily average consumption (DACON) of oxycodone controlled-release tablets (OxyContin CR)and oxymorphone extended-release tablets (Opana ER) in patients with low back pain. STUDY DESIGN: An observational, retrospective cohort study enrolled patients with multiple prescriptions for oxycodone CR or oxymorphone ER tablets. These patients also had International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for low back pain. Pharmacy prescription medication claims data were obtained from a large commercially insured health plan in the U.S. Mean daily consumption was calculated for a 90-day period. METHODS: We used descriptive statistics to evaluate patient demographics and health plan characteristics. Univariate analyses were used to examine the data as observed. A generalized linear model with a gamma distribution and log-link function provided a sensitivity measure, adjusting for heterogeneity among patients and the skewed nature of the DACON variable. RESULTS: A total of 4,023 patients received oxycodone CR, and 374 patients received oxymorphone ER. The mean age of patients (standard deviation, SD) was 49.0 (11.6) years for oxycodone CR and 47.3 (10.6) years for oxymorphone ER. DACON of oxycodone CR was 3.2 tablets per day, and DACON of oxymorphone ER was 2.7 tablets per day (P < 0.01). Utilization of maximum-strength tablets of oxycodone CR 80 mg was 3.9 tablets per day, which was significantly higher, by one tablet per day, than the utilization of equipotent oxymorphone ER maximum-strength tablets of 40 mg at 2.9 tablets per day (P < 0.01). CONCLUSION: The use of oxycodone CR, measured as mean daily consumption over a 90-day period, was significantly higher than that for oxymorphone ER in these patients, a finding that could have financial implications for health care systems.

Exposure to potential CYP450 pharmacokinetic drug-drug interactions among osteoarthritis patients: incremental risk of multiple prescriptions.

Patients taking more than one drug metabolized through the cytochrome P450 (CYP450) enzyme system experience a drug-drug exposure (DDE), which puts them at risk for a potential pharmacokinetic drug-drug interaction (DDI), defined as two or more drugs interacting in such a way that the effectiveness and/or toxicity of one or all drugs are changed. Any patient subjected to a DDE is at risk for a potentially serious DDI, the epidemiology of which has not been thoroughly studied. Many drugs are metabolized primarily via the CYP450 enzyme system, including certain opioids used to manage moderate to severe chronic pain. We conducted a retrospective analysis of a large commercial claims database and a Medicare database to assess the prevalence of DDEs among patients with osteoarthritis taking CYP450-metabolized opioids. The overall prevalence of DDEs in this population was 26%, with females more likely to experience DDEs than males (28.4% vs. 21.0%, respectively). The number of unique concurrent prescriptions at baseline, gender, age, and Charlson Comorbidity Index were statistically significant predictors of DDEs (P < 0.05). This study challenged previous assumptions about DDEs in that advanced age was not positively associated with the risk of DDE. However, the number of prescriptions the patient received in the 90-day window prior to the index date was a risk factor. For patients taking at least two medications in the 90-day period prior to the index date, every additional prescription taken increased their risk for a DDE during the observation period by 138% (on average). The risk of DDE during the study period was threefold greater for patients with one medication in the 90-day period before index date compared with similar patients with no prescriptions in that same period before the index date. DDEs are more common than may be generally believed in patients with osteoarthritis, regardless of age, and can occur even in patients taking few medications. When selecting an opioid analgesic to treat osteoarthritis, physicians should consider the potential for exposure of these patients to drugs that could interact unfavorably.

Prevalence of exposure to potential CYP450 pharmacokinetic drug-drug interactions among patients with chronic low back pain taking opioids.

Drug-drug interactions (DDIs) have been defined as two or more drugs interacting in such a way that the effectiveness and/or toxicity of one or all drugs are changed. Patients taking more than one drug metabolized through the cytochrome P450 (CYP450) enzyme system, including some, but not all, opioids experience a drug-drug exposure (DDE), which may result in a potentially dangerous DDI. Using a retrospective analysis of a large commercial claims database and a Medicare database, we evaluated DDEs that have the potential to cause DDIs among chronic low back pain (cLBP) patients on long-term opioid analgesia, which metabolizes through the CYP450 enzyme system, concomitant with other CYP450-metabolized drug(s). The overall prevalence of DDEs among cLBP patients was 27%. Women had a higher prevalence of DDEs (30.6% vs. 22% for men). Patients aged 45 to 55 and 56 to 64 years had the highest prevalence of DDEs (30.4% and 29.8%, respectively), followed by patients 34 to 45 years (27.9%). For patients>65 years, the prevalence of DDEs was 23.1%. In general, the prevalence of DDEs was fairly consistent across age ranges in this population. This study suggests that DDEs are common in the cLBP population. When selecting an opioid to treat cLBP, physicians should consider the potential for exposure of these patients to drugs that might unfavorably interact and, for that reason, the use of opioids that do not rely on the CYP450 system as their primary means of metabolism might be worthy of consideration.

Economic implications of potential drug-drug interactions in chronic pain patients.

Chronic pain patients may be subject to polypharmacy because of long-term pharmacological pain treatment and additional comorbidities. Many chronic pain patients expose themselves to potential drug-drug interactions (DDIs) and these interactions can have unintended and severe consequences. Prevalence and costs associated with DDIs are inconsistent and has led to an inadequate level of awareness among the medical community; therefore, it has become necessary to re-evaluate the rates of DDIs in chronic pain patients. Utilizing medical and prescription claims databases, five studies were conducted to assess the health care utilization of and associated financial payments for patients >18 years with chronic noncancer pain. The studies evaluated drug-drug exposures with the potential to cause DDIs specifically occurring through the CYP450 enzyme system. The studies reported that drug-drug exposures are prevalent, costly and can occur in any age group and that physicians should consider ways to limit their patients' exposure to potential DDIs.

Daily average consumption of 2 long-acting opioids: an interrupted time series analysis.

BACKGROUND: Oxycodone controlled release (CR) and oxymorphone extended release (ER) are frequently prescribed long-acting opioids, which are approved for twice-daily dosing. The US Food and Drug Administration approved a reformulated crush-resistant version of oxycodone CR in April 2010. OBJECTIVE: To compare the daily average consumption (DACON) for oxycodone CR and for oxymorphone ER before and after the introduction of the reformulated, crush-resistant version of oxycodone CR. METHODS: This was a retrospective claims database analysis using pharmacy claims from the MarketScan database for the period from January 2010 through March 2011. The interrupted time series analysis was used to evaluate the impact of the introduction of reformulated oxycodone CR on the DACON of the 2 drugs-oxycodone CR and oxymorphone ER. The source of the databases included private-sector health data from more than 150 medium and large employers. All prescription claims containing oxycodone CR and oxymorphone ER dispensed to members from January 1, 2010, to March 31, 2011, were included in the analysis. Prescription claims containing duplicate National Drug Codes, missing member identification, invalid quantities or inaccurate days supply of either drug, and DACON values of <1 and >500 were removed. RESULTS: The database yielded 483,063 prescription claims for oxycodone CR and oxymorphone ER from January 1, 2010, to March 31, 2011. The final sample consisted of 411,404 oxycodone CR prescriptions (traditional and reformulated) dispensed to 85,150 members and 62,656 oxymorphone ER prescriptions dispensed to 11,931 members. Before the introduction of reformulated oxycodone CR, DACON values for the highest strength available for each of the 2 drugs were 0.51 tablets higher for oxycodone CR than for oxymorphone ER, with mean DACON values of 3.5 for oxycodone CR and 3.0 for oxymorphone ER (P <.001). The differences of mean DACON between the 2 drugs for all lower strengths were 0.46 tablets, with mean DACON values of 2.7 for oxycodone CR and 2.3 for oxymorphone ER (P <.001). After the introduction of the new formulation, the difference in mean DACON between the 2 drugs was slightly lower: 0.45 tablets for the highest-strength and 0.40 tablets for the lower-strength pairs. Regression analyses showed that the immediate and overall impact of the reformulation of oxycodone CR on the DACON of oxycodone CR was minimal, whereas no changes were seen in the DACON of oxymorphone ER. The estimated DACON for oxycodone CR decreased by 0.1 tablets, or 3.7% (P <.001), 6 months after the new formulation was introduced. CONCLUSION: The mean DACON was 0.4 tablets per day higher for oxycodone CR compared with oxymorphone ER for all dosage strengths for the entire study period. After the introduction of the reformulated oxycodone CR, the DACON for this drug was slightly mitigated; however, there was a minimal impact on the mean differences between oxycodone CR and oxymorphone ER.

Economic impact of potential drug-drug interactions in opioid analgesics.

OBJECTIVE: Patients managing chronic non-cancer pain with cytochrome P450 (CYP450)-metabolized opioid analgesics who concurrently take another CYP450-metabolized medication experience a drug-drug exposure (DDE), which puts them at risk for a pharmacokinetic drug-drug interaction (PK DDI). This study examined the economic impact of incident DDEs with the potential to cause PK DDIs compared to similar patients without such exposure. STUDY DESIGN: This retrospective analysis used paid claims from a large, commercially insured population during January 1, 2004 through December 31, 2008. METHODS: Propensity matching was used to control for baseline differences in comparisons between 85,043 exposed and 85,043 non-exposed patients. RESULTS: Comparisons yielded mean total costs 6 months after the DDEs that were significantly higher in subjects with DDE versus matched subjects without DDE [$8165 (SD $11,357) vs. $7498 (SD $11,668), respectively, p<0.01] resulting in a difference of $667. This was driven by medical costs [$5520 (SD $10,505) vs. $5222 (SD $10,689), respectively, p<0.01] a $298 difference, and total prescription costs [$2646 (SD $3262) vs. $2276 (SD $3907), respectively, p<0.01] a $369 difference. LIMITATIONS: The study design demonstrates associations only and cannot establish causal relationships. Further, relevant DDEs were not included if concurrent consumption occurred outside the index period and when CYP450 substances were consumed that are not reflected in pharmacy claims (herbals, over-the-counter medications). CONCLUSION: Since concurrent exposure to DDEs with the potential to cause PK DDIs may be relatively common, policy decisions-makers should consider the use of long-acting opioids that are not metabolized through the CYP450 pathway.

Comparing healthcare costs of Medicaid patients with postherpetic neuralgia (PHN) treated with lidocaine patch 5% versus gabapentin or pregabalin.

OBJECTIVE: To compare healthcare resource utilization and costs of postherpetic neuralgia (PHN) patients initiating lidocaine patch 5% (lidocaine patch) or oral gabapentin/pregabalin. METHODS: Patients with PHN diagnosis, or herpes zoster diagnosis and ≥30 days PHN-recommended treatment were selected from de-identified Medicaid claims data from Florida, Iowa, Missouri, and New Jersey, 1999-2007. Patients initiated monotherapy with lidocaine patch or gabapentin/pregabalin after PHN diagnosis, had continuous eligibility 6 months before (baseline) and 6 months after (study period) medication index date, and were ≥18 years old. Lidocaine patch patients were matched to gabapentin/pregabalin patients based on their propensity to initiate treatment. Study period resource utilization and costs from a Medicaid perspective were compared between treatment groups using univariate analysis. RESULTS: Matched patients were on average 61.3 years old, approximately 73% were women, and 55% had other painful conditions during the baseline period. 6-month per patient PHN-related prescription drug costs were similar for matched lidocaine patch (n=312) and gabapentin/pregabalin (n=312) patients ($854 vs. 820, p=0.75), while PHN-related medical costs appeared lower in the lidocaine patch group ($145 vs. 353, p=0.12). Furthermore, there were no statistically significant differences between treatment groups during the observation period in overall resource utilization, total prescription drug costs, and total medical costs per patient. CONCLUSIONS: In spite of higher list prices, PHN patients treated with lidocaine patch cost no more than patients treated with gabapentin or pregabalin in terms of overall healthcare costs over the 6-month study period. The study suggests that PHN-related medical costs may be lower among lidocaine patch patients. LIMITATIONS: Findings are based on a Medicaid sample and may not be generalizable to all PHN patients.