Objective. To determine the epidemiologic features and symptom characteristics of fibromyalgia (FM) in Japan, and compare them with those for other chronic pain (CP) diagnoses.Methods. An internet survey was conducted in June and July 2011. The questionnaire consisted of 111 questions, including assessments of the Japanese version of the 2010 American College of Rheumatology preliminary diagnostic criteria for FM, the Japanese Fibromyalgia Impact Questionnaire, and additional questions regarding pain and lifestyle. Results. The questionnaire was completed by 20,407 male and female respondents in all prefectures of Japan. Of the survey population, 2,524 respondents (12.4%) reported symptoms consistent with CP; of these, 425 (2.1%) reported symptoms consistent with FM. Among respondents with FM and CP, 61% and 53%, respectively, were women. Pain severity and Widespread Pain Index scores were significantly higher in respondents meeting the diagnostic criteria for FM than in those meeting the criteria for CP. In terms of symptom severity scores, the proportions of respondents reporting the 3 major symptoms as "highly applicable" and greater numbers of 41 somatic symptoms were higher among respondents with FM than among those with CP. The incidence of FM in the present survey was similar to that reported (1.7%) in a study of FM in Japan in 2003, despite the use of the newer, easier to use 2010 diagnostic criteria. Conclusion. Because FM usually presents with more severe and more widely distributed pain, as well as more nonpainful symptoms than CP, our results suggest that FM is a different clinical phenotype of CP.

BackgroundOxycodone is one of the options for the management of CLBP in patients with an inadequate response to other analgesics. However, oxycodone is not yet approved for noncancer pain in Japan. Here, we assessed the efficacy and long-term safety of S-8117, a controlled-release oxycodone formulation, for the management of Japanese CLBP patients.Patients and methodsAn initial enriched enrollment randomized withdrawal, double-blind, placebo-controlled, 5-week phase III trial was conducted across 54 centers in Japan to assess the efficacy of S-8117 vs placebo in moderate-to-severe CLBP patients. Subsequently, a 52-week, open-label, single-arm study was conducted across 53 centers in Japan to evaluate the long-term safety of S-8117. The primary endpoint was the time to inadequate analgesic response during 35 days of the double-blind period. Secondary endpoints were the percentages of patients with inadequate analgesic response, discontinuation rate due to inadequate analgesic effects or AEs, and changes in scores of BPI severity, BPI pain interference, SF-36, and Roland-Morris Disability Questionnaire. Safety was assessed as the incidence of AEs and ADRs.ResultsOf the 189 patients enrolled in the double-blind study, 130 patients who completed the initial titration period were randomized 1:1 to receive either S-8117 (n=62) or placebo (n=68). Baseline characteristics were comparable across the study groups. The time to inadequate analgesic response was significantly longer in patients treated with S-8117 than placebo (P=0.0095). Secondary endpoints corroborated the efficacy of S-8117 vs placebo. Overall, 478 AEs were reported in 73/75 patients in the long-term study. The most frequent ADRs were somnolence, constipation, and nausea. No case of drug dependence was reported in the long-term study.ConclusionShort-term efficacy vs placebo and long-term safety of S-8117 were demonstrated for the management of Japanese patients with moderate-to-severe CLBP.

IntroductionDuloxetine has demonstrated efficacy in chronic low back pain (CLBP). We examined the predictors of response to duloxetine for CLBP.Patients and methodsThis was a post hoc analysis of pooled data from 4 double-blind, ran-domized, placebo-controlled trials of duloxetine (60 mg/day for 12–14 weeks) in adult patients with CLBP. Primary outcome was proportion of patients with ≥30% reduction in Brief Pain Inventory (BPI) average pain (“pain reduction”) at 12–14 weeks. The proportion of patients with ≥30% and ≥50% (secondary outcome) pain reduction in duloxetine and placebo groups was compared. Variables for responder analyses were early improvement (≥15% pain reduction at Week 2), sex, age, baseline BPI average pain score, duration of CLBP, and number of painful body sites according to the Michigan Body Map (≥2 vs 1 [isolated CLBP]; 1 trial); relative risk (RR) and 95% confidence interval (CI) were calculated.ResultsCompared with placebo (n = 653), a greater proportion of duloxetine-treated patients (n = 642) achieved ≥30% (59.7% vs 47.8%; P < 0.001) and ≥50% pain reduction (48.6% vs 35.1%; P < 0.001). Among duloxetine-treated patients, early improvement was associated with greater likelihood of ≥30% (RR [95% CI], 2.91 [2.30–3.67]) or ≥50% (3.24 [2.44–4.31]) pain reduction. Women were slightly more likely than men to achieve ≥30% (RR [95% CI], 1.14 [1.00–1.30]) or ≥50% (1.17 [0.99–1.38]) pain reduction. Response rates were similar between age, CLBP duration, and baseline BPI average pain score subgroups. Patients with ≥2 painful sites were more likely to respond to duloxetine 60 mg relative to placebo than patients with isolated CLBP (RR, duloxetine vs placebo [95% CI]: ≥30% reduction, ≥2 painful sites 1.40 [1.18–1.66], isolated CLBP 1.07 [0.78–1.48]; ≥50% reduction, ≥2 painful sites 1.51 [1.20–1.89], isolated CLBP 1.23 [0.81–1.88]).ConclusionEarly pain reduction was indicative of overall response. Patients with multiple painful sites had more benefit from duloxetine than patients with isolated CLBP.

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PurposeTo assess long-term safety, tolerability, and efficacy of duloxetine in Japanese patients with chronic knee pain due to osteoarthritis.MethodsIn this open-label extension study (NCT02335346), Japanese patients with knee osteoarthritis and pain (Brief Pain Inventory [BPI] – Severity average pain score ≥4 at start of randomized trial) who had previously received duloxetine 60 mg/day or placebo for 14 weeks in a double-blind randomized trial entered the extension and received duloxetine 60 mg/day for 48 weeks. The primary outcome was safety/tolerability, secondary outcomes were change in BPI-Severity (BPI-S) average pain, BPI-Interference (BPI-I), Patient Global Impression-Improvement (PGI-I), Clinical Global Impression-Improvement (CGI-I), 36-item Short-Form Health Survey (SF36), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and exploratory outcomes were knee range of motion (efficacy outcome) and Kellgren–Lawrence grade (safety outcome).ResultsOf 323 patients who completed the randomized trial, 93 (50 placebo, 43 duloxetine) entered the extension. Most patients (85, 91.4%) experienced an adverse event, most commonly constipation, nasopharyngitis, somnolence, and dry mouth (≥10% of patients). There were eight serious adverse events in seven patients and no deaths. No obvious duloxetine-related changes were observed in laboratory tests, vital signs, or electrocardiograms. The change from baseline in BPI-S average pain score was significant throughout the extension. Significant reductions in BPI-I, PGI-I, CGI-I, WOMAC, and SF36 scores were also maintained through 52 weeks. There were no substantial changes in range of motion or Kellgren–Lawrence grade.ConclusionIn Japanese patients with chronic knee pain due to osteoarthritis, long-term treatment with duloxetine was well tolerated and associated with sustained improvements in pain and health-related quality of life without radiographic deterioration.