American Pain Society (APS) 31st Annual Scientific Meeting

Honolulu, HI, May 16-19, 2012

Pregabalin for Painful Diabetic Peripheral Neuropathy Saves Costs and Leads to Better Adherence

A study examining healthcare costs for painful diabetic peripheral neuropathy (DPN) in elderly patients taking pregabalin versus comparators found that lower healthcare expenditures after treatment initiation may help optimize disease management because patients on less expensive medications are more likely to adhere to their regimens. The results were presented in a poster session at the APS meeting.

For this retrospective cohort analysis, the researchers used the MarketScan Database to identify patients with ≥1 diagnosis of DPN in 2008 within 30 days of their first prescription (index date) for pregabalin, duloxetine, gabapentin, or amitriptyline; continuous enrollment 12 months before and after the index date were required. Classification and Regressions Trees (CART) analysis was used to identify subpopulations with differences in costs before and after the index date, including in total, outpatient, inpatient, prescription, and disease-related costs, to determine if these costs were lower among patients starting pregabalin versus those starting on comparators. Pregabalin patients were randomized 1:1 using propensity score matching to each comparator based on demographic and clinical characteristics.

CART analysis consistently identified older age and high therapy adherence as variables resulting in lower costs with pregabalin relative to duloxetine (n=349), gabapentin (n=987), and amitriptyline (n=276). Using cutoff values, such as ≥65 years of age and ≥80% for proportion of days covered (PDC), changes in healthcare costs before and after the index date were estimated for pregabalin compared with comparators. Combinations examined included low age/low PDC; high age/low PDC; low age/high PDC; and high age/high PDC. For example, the results showed that for high age/high PDC, the differences in mean total costs before and after the index date were considerably lower with pregabalin compared with the three comparators ($3573 vs $8288 for duloxetine; $1423 vs $3167 for gabapentin; −$2285 vs $6160 for amitriptyline, respectively; P<.001), resulting from lower inpatient and outpatient costs (P<.001 for both). The results were further confirmed by a sensitivity analysis using a 50% PDC cutoff.

“The association of lower total costs among elderly patients with painful DPN who maintain high adherence to pregabalin relative to the comparators suggests the need for greater access to pregabalin in this patient population combined with strategies promoting adherence,” concluded the researchers.

—Eileen Koutnik-Fotopoulos

The study was funded by Pfizer.

Diclofenac Sodium Gel is Well Tolerated for Osteoarthritis in Younger and Older Patients

Treatment with topical diclofenac sodium 1% gel (DSG) was well tolerated for up to 1 year in patients aged <65 years and ≥65 years with osteoarthritis (OA) of the knee, validating its use for relief of OA pain in younger and older patients. The findings, presented in an APS poster session, were based on an open-label extension of two double-blind, randomized, 3-month trials of DSG in patients aged ≥35 years with a ≥6-month history of symptomatic Kellgren-Lawrence grade 1 to 3 knee OA.

For this study, patients applied 4 g DSG to one or both knees four times daily for 9 (continuing patients) or 12 (new patients) months; use of rescue acetaminophen (≤4 g/day) was permitted. The researchers monitored adverse events (AEs) throughout the study period, and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, stiffness, and physical function subscales were evaluated at baseline and at 3, 6, 9, and 12 months.

The safety population included 947 patients (n=575 patients <65 years and n=372 patients ≥65 years) who received ≥1 dose of DSG or placebo during the 12-week study or the extension. The results showed that nearly two-thirds of patients in both age groups experienced ≥1 AE (68.2% aged <65 years and 67.2% aged ≥65 years). The rate of application-site dermatitis was less in the younger patients compared with the older patients (8.7% vs 13.2%, respectively). The younger patients on DSG, however, experienced more gastrointestinal AEs and cardiac or vascular AEs than their older counterparts (9.4% and 3.5% vs 6.7% and 3.2%, respectively).

The researchers also assessed the efficacy of DSG. The study population included 291 patients (n=173 patients aged <65 years and n=118 patients aged ≥65 years) who completed WOMAC assessments through the 12-month visit. The results showed that both patient populations had similar baseline Kellgren-Lawrence OA severity grades and WOMAC pain, stiffness, and physical function subscale grades. Whereas efficacy was sustained in both age groups, it was slightly higher in younger patients versus the older patients.

—Eileen Koutnik-Fotopoulos

The study was funded by Novartis Consumer Health and Endo Pharmaceuticals, Inc.

G-QD Shows Early Treatment Response in Patients With Postherpetic Neuralgia

For patients with postherpetic neuralgia (PHN), pain reductions were observed after treatment with a once-daily gastroretentive formulation of gabapentin (G-QD) as early as the second day of dosing and continued for at least 10 weeks, according to data from two, 11-week, placebo-controlled PHN studies. Results were presented in a poster session at the APS meeting.

G-QD, which has been approved for the management of PHN, provides gradual release of gabapentin to the optimal site of absorption in the proximal small intestine and reduces the odds of saturating intestinal uptake of gabapentin, thereby enabling once-daily dosing.

In this study, the researchers integrated and analyzed data from 673 patients randomized to 1800 mg of G-QD (n=333) or placebo (n=340) to determine the onset of treatment response. Onset of response was defined as the first 2 consecutive days with significantly greater (P<.05) reduction in the Numeric Pain Rating Scale (NPRS) scores from baseline in the G-QD group compared with placebo. The investigators used an ANCOVA model with baseline pain as the covariate. Missing scores were not imputed. NPRS scores were recored every morning in an electronic diary. For this study, patients underwent a 2-week dose titration to 1800 mg, followed by 8 weeks of stable dosing, and 1-week of dose tapering. G-QD was administered with the evening meal.

The findings showed that as early as day 2, the day after treatment, significantly greater reductions in pain were seen in the G-QD group compared with placebo (6.7% vs 1.7%, respectively; P=.0043). Reductions in pain continued to increase, reaching a maximum around day 45 (−37.2% vs −26.2%, respectively; P=.0001) and remained statistically greater in the G-QD group than with the control group during the 10-week efficacy study period. The researchers also noted that at week 10 the mean percent last observation carried forward change in NPRS scores was considerably higher with G-QD compared with placebo (−37.5 vs −28.5, respectively; P=.006).

—Eileen Koutnik-Fotopoulos