Opioids for Osteoarthritis: Cross-Sectional Survey of Patient Perspectives and Satisfaction.

Patients often take opioids to relieve osteoarthritis (OA) pain despite limited benefits and potential harms. This study aimed to compare cross-sectional perspectives of patients that were taking prescription opioid (N = 471) or nonopioid medications (N = 185) for OA in terms of satisfaction, expectations of effectiveness, and concerns. Patients prescribed opioids (>7 days) reported more prior treatments (2.47 vs. 1.74), greater mean pain intensity (5.47 vs. 4.11), and worse quality of life (EQ-5D-5L index value mean 0.45 vs. 0.71) than patients prescribed nonopioid medications (all p < 0.0001). Based on linear regression models adjusting for demographics and pain intensity, patients prescribed opioids were less satisfied with overall regimen (3.40 vs. 3.67, p = 0.0322), had less belief that medications were meeting effectiveness expectations (2.72 vs. 3.13, p < 0.0001), and had more concerns about treatments being "not very good" (3.66 vs. 3.22, p = 0.0026) and addiction (3.30 vs. 2.65, p < 0.0001) than patients prescribed nonopioid regimens. When the models were replicated for subgroups with ≥30 days' medication regimen duration, the findings were consistent with the main analyses. Patients have concerns about the risk of opioid addiction, but those with greater disease burden and more prior treatments continue taking opioid regimens.

Predicting Treatment Responses in Patients With Osteoarthritis: Results From Two Phase III Tanezumab Randomized Clinical Trials.

Prediction of treatment responses is essential to move forward translational science. Our question was to identify patient-based variables that predicted responses to treatments. We conducted secondary analyses on pooled data from two randomized phase III clinical trials (NCT02697773 and NCT02709486) conducted in participants with moderate to severe osteoarthritis randomized to subcutaneous placebo (n = 514) or tanezumab 2.5 mg (n = 514). We used gradient boosted regression trees to identify variables that predicted Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain subscale scores at Week 16 and marginal plots to determine the directional relationship between each variable category and responses to placebo or tanezumab within the models. We also used Virtual Twins models to identify potential subgroups of response to the active treatment vs. placebo. We found that responses to placebo were predicted by baseline WOMAC Physical Function, baseline WOMAC Pain, the radiographic classification of the index joint, and the standard deviation of diary pain scores at baseline. In contrast, baseline WOMAC Pain along with failure of prior medications, duration of disease, and standard deviation of diary pain scores at baseline were predictive of tanezumab responses as expressed by the WOMAC Pain scores at Week 16. Those who responded to tanezumab vs. placebo were identified based on the radiographic classification of the index joint and either age or smoking status. These secondary-data analyses identified distinct and common patient-based variables to predict response to placebo or tanezumab. These findings will inform the design of future clinical trials, helping to move forward clinical pharmacology and translational science.

Opioid Prescribing for Osteoarthritis: Cross-Sectional Survey among Primary Care Physicians, Rheumatologists, and Orthopaedic Surgeons.

Opioids are often prescribed for osteoarthritis (OA) pain, despite recommendations to limit use due to minimal benefits and associated harms. This study aimed to assess physicians' practice patterns and perceptions regarding opioids by specialty one year following the Centers for Disease Control and Prevention (CDC) published guidance on opioid prescribing. The 139/153 (90.8%) physicians who reported prescribing opioids in the previous year reported decreased prescribing for mild OA (51.3%, 26.5% and 33.3% of primary care physicians, rheumatologists, and orthopaedic surgeons, respectively), moderate OA (50.0%, 47.1% and 48.1%) and severe OA (43.6%, 41.2% and 44.4%). Prescribing changes were attributed to the CDC guidelines for 58.9% of primary care physicians, 59.1% of rheumatologists, and 73.3% of orthopaedic surgeons. Strong opioids were mostly reserved as third-line treatment. Although treatment effectiveness post-CDC guidelines was not assessed, perceptions of efficacy and quality of life with opioids significantly differed across specialties, whereas perceptions of safety, convenience/acceptability and costs did not. Physicians generally agreed on the barriers to opioid prescribing, with fear of addiction and drug abuse being the most important. Across specialties, physicians reported decreased opioid prescribing for OA, irrespective of OA severity, and in most cases attributed changes in prescribing to the CDC guideline.

Factors associated with physician-reported treatment status of patients with osteoarthritis pain.

BACKGROUND: Osteoarthritis (OA) is typically associated with pain, but many patients are not treated. METHODS: This point in time study explored factors associated with treatment status, using logistic regression of data from the Adelphi OA Disease Specific Programme conducted in the United States. Patients' treatment status was based on physician-reported, current: 1) prescription medication for OA vs. none; and 2) physician treatment (prescription medication and/or recommendation for specified nonpharmacologic treatment for OA [physical or occupational therapy, acupuncture, transcutaneous electrical nerve stimulation, or cognitive behavior therapy/psychotherapy]) vs. self-management (no prescription medication or specified nonpharmacologic treatment). RESULTS: The 841 patients (including 57.0% knee OA, 31.9% hip OA) reported mild (45.4%) or moderate or severe (54.6%) average pain intensity over the last week. The majority were prescribed medication and/or recommended specified nonpharmacologic treatment; 218 were not prescription-medicated and 122 were self-managed. Bivariate analyses showed less severe patient-reported pain intensity and physician-rated OA severity, fewer joints affected by OA, lower proportion of joints affected by knee OA, better health status, lower body mass index, and lower ratings for cardiovascular and gastrointestinal risks, for those not prescribed medication (vs. prescription-medicated). Multivariate analyses confirmed factors significantly (p < 0.05) associated with prescription medication included (odds ratio): physician-rated current moderate OA severity (vs. mild, 2.03), patient-reported moderate OA severity 6 months ago (vs. mild, 1.71), knee OA (vs. not, 1.81), physician-recommended (0.28) and patient-reported (0.43) over-the-counter medication use (vs. not), prior surgery for OA (vs. not, 0.37); uncertain income was also significant. Factors significantly (p < 0.05) associated with physician treatment included (odds ratio): physician-recommended nonpharmacologic therapy requiring no/minimal medical supervision (vs. not, 2.21), physician-rated current moderate OA severity (vs. mild, 2.04), patient-reported over-the-counter medication use (vs. not, 0.26); uncertain time since diagnosis was also significant. Patient-reported pain intensity and most demographic factors were not significant in either model. CONCLUSIONS: Approximately 1 in 4 patients were not prescribed medication and 1 in 7 were self-managed, although many were using over-the-counter medications or nonpharmacologic therapies requiring no/minimal medical supervision. Multiple factors were significantly associated with treatment status, including OA severity and over-the-counter medication, but not pain intensity or most demographics.

Satisfaction with Medications Prescribed for Osteoarthritis: A Cross-Sectional Survey of Patients and Their Physicians in the United States.

INTRODUCTION: Satisfaction with medications prescribed for osteoarthritis (OA) varies; this study aimed to determine the factors associated with satisfaction in US patients and their physicians. METHODS: This point-in-time study used the Adelphi OA Disease Specific Programme (physicians identified from public lists reported on nine consecutive patients diagnosed with OA [any joint]: physicians and patients completed questionnaires). Patient's demographic, clinical, and treatment characteristics associated with patient-reported and physician-rated overall satisfaction with, and expectations of effectiveness of, medication for OA were assessed using multivariate linear regression. RESULTS: Responses from 572 patients (mean age 64.9 years, 60.5% female) currently prescribed medication for OA and 153 physicians (81 primary care, 35 rheumatologists, 37 orthopedic surgeons) were analyzed. Pain intensity was moderate or severe for 59.4% of patients. Greater patient-reported overall satisfaction with medication was significantly associated with (standardized beta, 95% confidence interval) exercise (0.12, 0.03-0.20), comorbid other musculoskeletal or painful conditions (vs none) (0.15, 0.06-0.24), and physicians' report that the best control had been achieved (0.12, 0.03-0.20); lack of efficacy was among factors associated with worse satisfaction. Greater patient-reported expectation of effectiveness was significantly associated with exercise (0.12, 0.03-0.21) and the most troublesome joint not being a knee, hip, or their back (0.08, 0.01-0.14). Greater physician-rated overall satisfaction with medication was significantly associated with their report that the best control had been achieved (0.18, 0.11-0.26), the most troublesome joint being a knee (0.08, 0.01-0.14), comorbid other musculoskeletal or painful conditions (0.07, 0.01-0.12), obesity (0.06, 0.00-0.11), and female patients (0.06, 0.00-0.11); lack of efficacy and adverse events/tolerability issues were among factors associated with worse satisfaction. For physicians, their report that the best control had been achieved (0.19, 0.11-0.27), the most troublesome joint being a knee (0.08, 0.00-0.15), improving (vs stable) OA (0.15, 0.07-0.24), and uncertain duration of OA (0.11, 0.02-0.21) were associated with greater perception that the medication was meeting patients' efficacy expectations. CONCLUSION: Although efficacy was strongly associated with both patients' and physicians' satisfaction with medication, other factors were also important, including exercise (for patients), tolerability (for physicians), and knee OA (for physicians).

Benefit-risk assessment and reporting in clinical trials of chronic pain treatments: IMMPACT recommendations.

ABSTRACT: Chronic pain clinical trials have historically assessed benefit and risk outcomes separately. However, a growing body of research suggests that a composite metric that accounts for benefit and risk in relation to each other can provide valuable insights into the effects of different treatments. Researchers and regulators have developed a variety of benefit-risk composite metrics, although the extent to which these methods apply to randomized clinical trials (RCTs) of chronic pain has not been evaluated in the published literature. This article was motivated by an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials consensus meeting and is based on the expert opinion of those who attended. In addition, a review of the benefit-risk assessment tools used in published chronic pain RCTs or highlighted by key professional organizations (ie, Cochrane, European Medicines Agency, Outcome Measures in Rheumatology, and U.S. Food and Drug Administration) was completed. Overall, the review found that benefit-risk metrics are not commonly used in RCTs of chronic pain despite the availability of published methods. A primary recommendation is that composite metrics of benefit-risk should be combined at the level of the individual patient, when possible, in addition to the benefit-risk assessment at the treatment group level. Both levels of analysis (individual and group) can provide valuable insights into the relationship between benefits and risks associated with specific treatments across different patient subpopulations. The systematic assessment of benefit-risk in clinical trials has the potential to enhance the clinical meaningfulness of RCT results.

Concern about addiction is associated with lower quality of life in patients with osteoarthritis: an exploratory, real-world data analysis.

PURPOSE: To evaluate the relationship between self-reported concerns about becoming addicted to a medication and health-related quality of life (HRQoL) in patients with osteoarthritis (OA). METHODS: This real-world study used patient-level cross-sectional survey data collected from the US Adelphi Disease Specific Programme (DSP). The DSP for OA selected 153 physicians who collected de-identified data on their next nine adult patients with OA. Each patient completed a disease-relevant survey, which included the Likert-scale question, "I am concerned about becoming addicted to my medicine," (CAA) with responses ranging from "completely disagree" [1] to "completely agree" [5]. HRQoL was measured by the EQ-5D-5L index value and the EQ Visual Analogue Scale (VAS). A set of ordinary least squares regressions using HRQoL measures as outcomes and CAA as a continuous predictor were estimated. Standardized effect size (ES) was used to gauge the magnitude of effects. RESULTS: A total of 866 patients with OA completed the survey (female, 61.2%; White, 77.7%; mean age, 64.2 years). Of the 775 patients who completed the CAA question, almost one-third responded that they "agree" (18%) or "completely agree" (11%), while 27% responded "completely disagree" and 20% "disagree." Regression analyses found that patients who have concerns about medication addiction have significantly different EQ-5D-5L index values and EQ VAS scores compared with patients who do not have this concern (p < 0.0001). CONCLUSION: Our findings suggest that concern about medication addiction in patients with OA may have an impact on patient HRQoL, with more concerned patients reporting poorer HRQoL outcomes.

Gender, age, disease severity, body mass index and diabetes may not affect response to subcutaneous tanezumab in patients with osteoarthritis after 16 weeks of treatment. A subgroup analysis of placebo-controlled trials.

AIM: To assess the impact of pre-specified patient characteristics on efficacy and safety of subcutaneous tanezumab in patients with osteoarthritis (OA). METHODS: Data were pooled from two (efficacy; N = 1545) or three (safety; N = 1754) phase 3 placebo-controlled trials. Change from baseline to week 16 in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain, WOMAC Physical Function and patient global assessment of OA (PGA-OA) scores was compared between tanezumab (2.5 and 5 mg) and placebo groups via analysis of covariance. Treatment-emergent adverse events (TEAEs) were summarised descriptively. Analyses were done in patient subgroups (men or women; age <65, ≥65, or ≥75 years; body mass index [BMI] <25, 25 to <30, 30 to <35 or ≥35 kg/m2 ; diabetes or no diabetes; baseline WOMAC Pain score <7 or ≥7; and Kellgren-Lawrence [KL] grades 2, 3 or 4 in the index joint) and the overall population. RESULTS: In all subgroups, improvements in WOMAC Pain were numerically greater and often statistically significant (P < .05) for both tanezumab groups compared with placebo. Results were similar for WOMAC Physical Function and PGA-OA. TEAE profiles were generally consistent across subgroups and similar to the overall population (ie slightly higher rates of TEAEs, serious TEAEs and severe TEAEs with tanezumab relative to placebo) with a few exceptions. Exceptions included women reporting slightly more TEAEs with tanezumab than men, and patients with diabetes reporting slightly more severe TEAEs with tanezumab than patients without diabetes. Additionally, TEAEs were more frequent with tanezumab than placebo in the age ≥65 and ≥75 years, but not the age <65 years, subgroups. CONCLUSIONS: Efficacy and safety/tolerability of tanezumab may not be meaningfully impacted by gender, age, BMI, diabetes status, baseline pain severity or KL grade in the index joint. Conclusions are limited by low patient number in some subgroups. Clinicaltrials.gov: NCT02697773, NCT02709486, NCT01089725.

Pain severity and healthcare resource utilization in patients with osteoarthritis in the United States.

OBJECTIVE: To evaluate healthcare resource utilization (HCRU) by osteoarthritis (OA) pain severity. METHODS: Cross-sectional surveys of US physicians and their patients were conducted between February and May 2017. Using the Numeric Rating Scale, patients were classified by self-reported pain intensity in the last week into mild (0-3), moderate (4-6), and severe (7-10) cohorts. Parameters assessed included clinical characteristics, HCRU, and current caregiver support. Descriptive statistics were obtained, and analysis of variance and chi-square tests were performed. RESULTS: Patients (n = 841) were mostly female (60.9%) and white (77.8%), with mean age of 64.6 years. Patients reported mild (45.4%), moderate (35.9%), and severe (18.7%) OA pain. Mean number of affected joints varied by pain severity (range mild: 2.7 to severe: 3.6; p < 0.0001). Pain severity was associated with an increased number of physician-reported and patient-reported overall healthcare provider visits (HCPs; both p < 0.001). As pain increased, patients reported an increased need for mobility aids, accessibility modifications to homes, and help with daily activities due to functional disability. The number of imaging tests used to diagnose OA was similar across pain severity but varied when used for monitoring (X-rays: p < 0.0001; computerized tomography scans: p < 0.0447). Hospitalization rates for OA were low but were significantly associated with pain severity (mild: 4.9%; severe: 11.5%). Emergency department visits were infrequent but increasing pain severity was associated with more prior and planned surgeries. CONCLUSION: Greater current pain was associated with more prior HCRU including imaging for monitoring progression, HCP visits including more specialty care, hospitalizations, surgery/planned surgery, and loss of independence due to functional disability. Yet rates of hospitalizations and X-ray use were still sizable even among patients with mild pain. These cross-sectional findings warrant longitudinal assessment to further elucidate the impact of pain on HCRU.

Multimodal Treatment Patterns for Osteoarthritis and Their Relationship to Patient-Reported Pain Severity: A Cross-Sectional Survey in the United States.

PURPOSE: The purpose of this study was to assess how patient-reported pain is related to osteoarthritis (OA) treatment patterns in routine clinical practice. PATIENTS AND METHODS: Data were collected between February and May 2017 from 153 United States (US) primary care physicians, rheumatologists, and orthopedic surgeons. Each invited up to nine consecutive patients to rate their OA pain in the last week. Physicians provided demographic, clinical, and treatment information for patients, including nonpharmacologic therapies ever recommended, currently recommended over-the-counter (OTC) medications, and currently and ever prescribed medications for the management of OA. Findings for patients with mild (0─3), moderate (4─6), and severe current pain (7─10) were compared using appropriate statistics. RESULTS: Among the 841 patients (61% female; mean 65 years; 57% knee OA), 45% reported mild, 36% moderate, and 19% severe current OA pain. Current treatment modalities differed by pain severity (P<0.05). Most patients (70%) had been recommended nonpharmacologic therapy and 40% were currently recommended OTC medications. More patients with moderate (81%) or severe pain (78%) currently received prescription medications, with or without nonpharmacologic therapy, versus those with mild pain (67%). Overall, 47% of patients currently received just one prescription drug, while 49% had received one prescription drug ever. Nonsteroidal anti-inflammatory drugs (NSAIDs) were the most common current (58%) and ever received (88%) prescriptions. Current NSAID prescriptions were not associated with pain severity. Acetaminophen recommendations, opioid prescriptions (current and ever), and multiple prescription medications tried were numerically highest in the severe pain group (all P<0.05 by pain severity). In all groups, >80% of treatment switches were due to lack of efficacy. CONCLUSION: Real-life treatment patterns for OA in the US are significantly associated with current patient-reported pain. Combining nonpharmacologic and pharmacologic treatments is common but higher pain ratings are associated with multiple failed prescription treatments. Current use of acetaminophen and opioids, but not NSAIDs, increases alongside pain severity.

Nerve Growth Factor Signaling and Its Contribution to Pain.

Nerve growth factor (NGF) is a neurotrophic protein essential for the growth, differentiation, and survival of sympathetic and sensory afferent neurons during development. A substantial body of evidence, based on both animal and human studies, demonstrates that NGF plays a pivotal role in modulation of nociception in adulthood. This has spurred development of a variety of novel analgesics that target the NGF signaling pathway. Here, we present a narrative review designed to summarize how NGF receptor activation and downstream signaling alters nociception through direct sensitization of nociceptors at the site of injury and changes in gene expression in the dorsal root ganglion that collectively increase nociceptive signaling from the periphery to the central nervous system. This review illustrates that NGF has a well-known and multifunctional role in nociceptive processing, although the precise signaling pathways downstream of NGF receptor activation that mediate nociception are complex and not completely understood. Additionally, much of the existing knowledge derives from studies performed in animal models and may not accurately represent the human condition. However, available data establish a role for NGF in the modulation of nociception through effects on the release of inflammatory mediators, nociceptive ion channel/receptor activity, nociceptive gene expression, and local neuronal sprouting. The role of NGF in nociception and the generation and/or maintenance of chronic pain has led to it becoming a novel and attractive target of pain therapeutics for the treatment of chronic pain conditions.

Interpretation of chronic pain clinical trial outcomes: IMMPACT recommended considerations.

Interpreting randomized clinical trials (RCTs) is crucial to making decisions regarding the use of analgesic treatments in clinical practice. In this article, we report on an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) consensus meeting organized by the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks, the purpose of which was to recommend approaches that facilitate interpretation of analgesic RCTs. We review issues to consider when drawing conclusions from RCTs, as well as common methods for reporting RCT results and the limitations of each method. These issues include the type of trial, study design, statistical analysis methods, magnitude of the estimated beneficial and harmful effects and associated precision, availability of alternative treatments and their benefit-risk profile, clinical importance of the change from baseline both within and between groups, presentation of the outcome data, and the limitations of the approaches used.

Onset and maintenance of efficacy of subcutaneous tanezumab in patients with moderate to severe osteoarthritis of the knee or hip: A 16-week dose-titration study.

OBJECTIVE: To examine the onset and maintenance of efficacy of subcutaneous tanezumab for pain relief and functional improvement in difficult-to-treat patients with moderate-to-severe osteoarthritis (OA) in a 16-week dose-titration study (NCT02697773). METHODS: Patients were randomized to placebo (placebo group) or tanezumab 2.5 mg at baseline and week 8 (tanezumab 2.5 mg group), or tanezumab 2.5 mg at baseline and tanezumab 5 mg at week 8 (tanezumab 2.5/5 mg group). Analyses included change from baseline in average daily index joint pain and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain and Physical Function, and treatment responses (WOMAC Pain improvement criteria and Outcome Measures in Rheumatology-Osteoarthritis Research Society International [OMERACT-OARSI] criteria). RESULTS: The 696 patients received placebo (n = 232), tanezumab 2.5 mg (n = 231), or tanezumab 2.5/5 mg (n = 233). Average daily index joint pain was statistically significantly improved within the first week (day 3-5) with tanezumab 2.5 mg compared with placebo. On first post-randomization WOMAC measurement (week 2), both tanezumab groups had statistically significant improvements compared with placebo in WOMAC Pain and Physical Function, and more tanezumab-treated patients achieved treatment response criteria (≥30%, ≥50%, or ≥70% reduction in WOMAC Pain or OMERACT-OARSI response). Efficacy was generally maintained throughout the 16-week treatment period. CONCLUSION: Subcutaneous tanezumab provided statistically significant improvements compared with placebo in average daily index joint pain within the first week and WOMAC Pain and Physical Function (week 2) that were generally maintained throughout the 16-week treatment period. Tanezumab 5 mg provided only modest additional efficacy over tanezumab 2.5 mg.

Nerve growth factor antibody for the treatment of osteoarthritis pain and chronic low-back pain: mechanism of action in the context of efficacy and safety.

Chronic pain continues to be a significant global burden despite the availability of a variety of nonpharmacologic and pharmacologic treatment options. Thus, there is a need for new analgesics with novel mechanisms of action. In this regard, antibodies directed against nerve growth factor (NGF-Abs) are a new class of agents in development for the treatment of chronic pain conditions such as osteoarthritis and chronic low-back pain. This comprehensive narrative review summarizes evidence supporting pronociceptive functions for NGF that include contributing to peripheral and central sensitization through tropomyosin receptor kinase A activation and stimulation of local neuronal sprouting. The potential role of NGF in osteoarthritis and chronic low-back pain signaling is also examined to provide a mechanistic basis for the observed efficacy of NGF-Abs in clinical trials of these particular pain states. Finally, the safety profile of NGF-Abs in terms of common adverse events, joint safety, and nerve structure/function is discussed.

Pooled analysis of tanezumab efficacy and safety with subgroup analyses of phase III clinical trials in patients with osteoarthritis pain of the knee or hip.

PURPOSE: A pooled analysis was conducted to evaluate tanezumab efficacy and safety in patients with osteoarthritis (OA), including subgroup analyses of at-risk patients with diabetes, severe OA symptoms, and those aged ≥65 years. PATIENTS AND METHODS: Data from phase III placebo-controlled clinical trials of patients with moderate-to-severe OA of the knee or hip were pooled to evaluate tanezumab efficacy (four trials) and safety (nine trials). Patients received intravenous tanezumab, tanezumab plus an oral NSAID (naproxen, celecoxib, or diclofenac), active comparator (naproxen, celecoxib, diclofenac, or oxycodone), or placebo. Efficacy assessments included change from baseline to week 16 in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and physical function scores, Patient's Global Assessment (PGA) of OA, and percentage of patients with ≥30%, ≥50%, ≥70%, and ≥90% improvement in WOMAC pain. Safety assessments included adverse event (AE) documentation and physical and neurologic examinations. RESULTS: Tanezumab significantly improved all efficacy end points in the overall population. Efficacy in at-risk patient subgroups was similar to the overall population. Incidence of AEs was highest in the tanezumab plus NSAID group and lowest in the placebo group. Incidence of AEs in the tanezumab monotherapy and active comparator groups was similar. Overall incidence of AEs was similar across subgroups. AEs of abnormal peripheral sensation were more frequently reported in tanezumab-treated patients compared with placebo or active comparator. Patients receiving active comparator had a slightly higher incidence of AEs suggestive of postganglionic sympathetic dysfunction. CONCLUSION: Tanezumab consistently provided significant improvement of pain, physical function, and PGA in individuals with OA, including patients with diabetes, severe OA symptoms, or aged ≥65 years. No increased safety risk was observed in at-risk patient subgroups. TRIAL REGISTRATION: NCT00733902, NCT00744471, NCT00830063, NCT00863304, NCT00809354, NCT00864097, NCT00863772, NCT01089725, NCT00985621.

Responsiveness of Single versus Composite Measures of Pain in Knee Osteoarthritis.

OBJECTIVE: In rheumatoid arthritis, composite outcomes constructed from a combination of outcome measures are widely used to enhance responsiveness (sensitivity to change) and comprehensively summarize response. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain is the primary outcome measure in many osteoarthritis (OA) trials. Information from other outcomes, such as rescue medication use and other WOMAC subscales, could be added to create composite outcomes, but the sensitivity of such a composite has not been tested. METHODS: We used data from a completed trial of tanezumab for knee OA (NCT00733902). The WOMAC questionnaire and rescue medication use were measured at several timepoints, up to 16 weeks. Pain and rescue medication outcomes were standardized and combined into 3 composite outcomes through principal components analysis to produce 1 score (composite outcome) and their responsiveness was compared to WOMAC pain, the standard. We pooled all treatment doses of tanezumab into 1 treatment group, for simplicity, and compared this to the control group (placebo). RESULTS: The composite outcomes showed modestly, but not statistically significantly greater responsiveness when compared to WOMAC pain alone. Adding information on rescue medication to the composite improved responsiveness. While improvements in sensitivity were modest, the required sample sizes for trials using composites was 20-40% less than trials using WOMAC pain alone. CONCLUSION: Combining information from related but distinct outcomes considered relevant to a particular treatment improved responsiveness, could reduce sample size requirements in OA trials, and might offer a way to better detect treatment efficacy in OA trials.

Participant Preferences for Pharmacologic Chronic Pain Treatment Trial Characteristics: An ACTTION Adaptive Choice-Based Conjoint Study.

Barriers to clinical trial recruitment can delay study completion, potentially resulting in increased costs and an unrepresentative sample. In the current study of 150 participants with chronic pain, we used a computerized adaptive choice-based conjoint survey that included 8 characteristics that may affect enrollment in pharmacologic pain treatment trials (ie, treatment allocation, frequency of pain ratings, treatment administration method, current medications, number of study visits, availability of evening and weekend visits, invasiveness of laboratory procedures, payment). These data were analyzed using Sawtooth Software ver. 8.4.8 (Sawtooth Software, Inc, Orem, UT), which identifies the characteristics that dominate participants' decisions across multiple sets of potential trials. Three characteristics had the largest relative importance in participants' trial preferences: 1) invasiveness of required laboratory procedures (ie, 22%), with no procedures or blood tests preferred over ice-water sensory testing or skin biopsy; 2) ability to continue current pain medications (21%); and 3) payment for study participation (21%), with higher payment preferred. The fourth most important characteristic was number of study visits (13%), with participants preferring fewer in-person visits and more phone contacts. Understanding the preferences of potential participants is an important step toward enhancing enrollment in pain treatment trials. PERSPECTIVE: This article presents the preferences of individuals with chronic pain conditions regarding modifiable pain treatment trial characteristics (eg, number of study visits, payment, treatment allocation). These findings may help to improve enrollment into analgesic clinical trials and in turn accelerate the development of new pain treatments.

When Is Osteonecrosis Not Osteonecrosis?: Adjudication of Reported Serious Adverse Joint Events in the Tanezumab Clinical Development Program.

OBJECTIVE: Tanezumab, a monoclonal antibody against nerve growth factor, has demonstrated efficacy in clinical trials of chronic pain in osteoarthritis (OA) and chronic low back pain. Unexpected adverse events (AEs) described as osteonecrosis (ON) occurred during tanezumab development, leading the US Food and Drug Administration to impose a partial clinical hold for all indications except cancer pain. A blinded Adjudication Committee (AC) including orthopedic surgeons, rheumatologists, and an orthopedic pathologist reviewed and adjudicated joint-related AEs in the tanezumab clinical program. METHODS: The AC adjudicated all reported cases of ON as well as cases of total joint replacements (TJRs) not reported as ON for which radiographs obtained within 9 months of the surgery were available. The AC prespecified categories for joint safety events including primary ON, worsening OA (rapid progression of OA [RPOA], normal progression of OA, insufficient information to distinguish between rapid and normal progression of OA), other, or insufficient information to distinguish between primary ON and worsening OA or another diagnosis. RESULTS: The AC reviewed events in 249 of 386 patients with an investigator-reported AE of ON and/or a TJR. Two events were adjudicated as primary ON, 200 events were adjudicated as worsening OA (68 of which were classified as RPOA), 29 events had another diagnosis, 11 had insufficient information to distinguish primary ON from worsening OA, and 7 did not have committee member consensus. CONCLUSION: Despite initial reports, tanezumab treatment was not associated with an increase in ON but was associated with an increase in RPOA. Higher doses of tanezumab, tanezumab administered with nonsteroidal antiinflammatory drugs, and preexisting subchondral insufficiency fractures were risk factors for RPOA in this cohort.

Antagonism of nerve growth factor-TrkA signaling and the relief of pain.

Nerve growth factor (NGF) was originally discovered as a neurotrophic factor essential for the survival of sensory and sympathetic neurons during development. However, in the adult NGF has been found to play an important role in nociceptor sensitization after tissue injury. The authors outline mechanisms by which NGF activation of its cognate receptor, tropomyosin-related kinase A receptor, regulates a host of ion channels, receptors, and signaling molecules to enhance acute and chronic pain. The authors also document that peripherally restricted antagonism of NGF-tropomyosin-related kinase A receptor signaling is effective for controlling human pain while appearing to maintain normal nociceptor function. Understanding whether there are any unexpected adverse events and how humans may change their behavior and use of the injured/degenerating tissue after significant pain relief without sedation will be required to fully appreciate the patient populations that may benefit from these therapies targeting NGF.