BACKGROUND: Placebo controls are essential in evaluating the effectiveness of medical treatments. Although it is unclear whether different placebo interventions for osteoarthritis vary in efficacy, systematic differences would substantially affect interpretation of the results of placebo-controlled trials.
OBJECTIVE: To evaluate the effects of alternative placebo types on pain outcomes in knee osteoarthritis.
DATA SOURCES: MEDLINE, EMBASE, Web of Science, Google Scholar, and Cochrane Database from inception through 1 June 2015 and unpublished data.
STUDY SELECTION: 149 randomized trials of adults with knee osteoarthritis that reported pain outcomes and compared widely used pharmaceuticals against oral, intra-articular, topical, and oral plus topical placebos.
DATA EXTRACTION: Study data were independently double-extracted; study quality was assessed by using the Cochrane risk of bias tool.
DATA SYNTHESIS: Placebo effects that were evaluated by using a network meta-analysis with 4 separate placebo nodes (differential model) showed that intra-articular placebo (effect size, 0.29 [95% credible interval, 0.09 to 0.49]) and topical placebo (effect size, 0.20 [credible interval, 0.02 to 0.38]) had significantly greater effect sizes than did oral placebo. This differential model showed marked differences in the relative efficacies and hierarchy of the active treatments compared with a network model that considered all placebos equivalent. In the model accounting for differential effects, intra-articular and topical therapies were superior to oral treatments in reducing pain. When these differential effects were ignored, oral nonsteroidal anti-inflammatory drugs were superior.
LIMITATIONS: Few studies compared different placebos directly. The study could not decisively conclude whether disease severity and co-interventions systematically differed between trials evaluating different placebos.
CONCLUSION: All placebos are not equal, and some can trigger clinically relevant responses. Differential placebo effects can substantially alter estimates of the relative efficacies of active treatments, an important consideration for the design of clinical trials and interpretation of their results.
PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality.
The search results of a recent systematic review of prospective, randomized, placebo-controlled trials on hyaluronic acid injections for knee arthritis were updated and reviewed for funding source and qualitative conclusions. Forty-eight studies were identified; 30 (62.5%) were industry funded, and 3 (6.25%) were not. Fifteen (31.3%) studies did not identify a funding source. An association was observed between a reported potential financial conflict of interest of the author and the qualitative conclusion (P=0.018). None of the studies with a reported financial conflict of interest of at least one author had an unfavorable conclusion; 11 (35%) of the 31 studies with no industry-affiliated authors indicated that hyaluronic acid injection for knee osteoarthritis was no more effective than a placebo injection.
BACKGROUND: Although accepted as a conservative treatment option for knee osteoarthritis, the debate about the effectiveness of intra-articular treatment with hyaluronic acid (HA) is still ongoing because of contrasting outcomes in different clinical studies. Several well designed clinical studies showed a significant improvement in pain at follow-up compared with baseline but no significant improvement comparing the efficacy of HA with placebo (saline) or with other conservative treatment options. Notwithstanding the effectiveness of different types of intra-articular HA products, the question of whether one HA product is better than another is still unanswered. In this systematic review we compare the effects of intra-articularly administered HA with intra-articularly administered placebo in general and, more specifically, the effects of individual HA products with placebo. We also compare the efficacy of different HA products.
METHODS: A systematic review of randomized controlled trials (RCTs) was conducted using databases including MEDLINE, Cochrane Database of Systematic Reviews, Cochrane Clinical Trial Register and EMBASE.
RESULTS: Seventy-four RCTs were included in this systematic review. HA improves pain by approximately 40-50% compared with baseline levels. However, when compared with saline the difference in efficacy is not that large. Due to a large 'placebo effect' of saline (approximately 30% pain reduction, persisting for at least 3 months) we determined a weighted mean difference between the efficacy of HA and saline of just 10.20 using the visual analog scale for pain. It is debatable whether this difference reaches the minimum clinically important difference. Comparing the different HA products, which vary in the molecular weight, concentration, and volume of HA, we were not able to conclude that one brand has a better efficacy than another due to the heterogeneity of the studies and outcomes.
DISCUSSION: In the future it will be important to determine the exact mechanism of action of placebo as this may give us an idea of how to treat osteoarthritis more efficiently. Due to the limitations of this review (follow-up of just 3 months and large heterogeneity of the included studies), it is also important to compare the different HA products to determine which product(s), or which molecular weight range, concentration, or volume of HA is the best option to treat osteoarthritis. Our recommendation is to start large (multicenter) RCTs to give us more evidence about the efficacy of the different HA products.
BACKGROUND: Viscosupplementation, the intra-articular injection of hyaluronic acid, is widely used for symptomatic knee osteoarthritis. PURPOSE: To assess the benefits and risks of viscosupplementation for adults with symptomatic knee osteoarthritis. DATA SOURCES: MEDLINE (1966 to January 2012), EMBASE (1980 to January 2012), the Cochrane Central Register of Controlled Trials (1970 to January 2012), and other sources. STUDY SELECTION: Randomized trials in any language that compared viscosupplementation with sham or nonintervention control in adults with knee osteoarthritis. DATA EXTRACTION: Primary outcomes were pain intensity and flare-ups. Secondary outcomes included function and serious adverse events. Reviewers used duplicate abstractions, assessed study quality, pooled data by using a random-effects model, examined funnel plots, and explored heterogeneity by using meta-regression. DATA SYNTHESIS: Eighty-nine trials involving 12 667 adults met inclusion criteria. Sixty-eight had a sham control, 40 had a follow-up duration greater than 3 months, and 22 used cross-linked forms of hyaluronic acid. Overall, 71 trials (9617 patients) showed that viscosupplementation moderately reduced pain (effect size, -0.37 [95% CI, -0.46 to -0.28]). There was important between-trial heterogeneity and an asymmetrical funnel plot: Trial size, blinded outcome assessment, and publication status were associated with effect size. Five unpublished trials (1149 patients) showed an effect size of -0.03 (CI, -0.14 to 0.09). Eighteen large trials with blinded outcome assessment (5094 patients) showed a clinically irrelevant effect size of -0.11 (CI, -0.18 to -0.04). Six trials (811 patients) showed that viscosupplementation increased, although not statistically significantly, the risk for flare-ups (relative risk, 1.51 [CI, 0.84 to 2.72]). Fourteen trials (3667 patients) showed that viscosupplementation increased the risk for serious adverse events (relative risk, 1.41 [CI, 1.02 to 1.97]). LIMITATIONS: Trial quality was generally low. Safety data were often not reported. CONCLUSION: In patients with knee osteoarthritis, viscosupplementation is associated with a small and clinically irrelevant benefit and an increased risk for serious adverse events. PRIMARY FUNDING SOURCE: Arco Foundation.
Background: Osteoarthritis (OA) is the most prevalent chronic joint disorder worldwide and is associated with significant pain and disability. Objectives: To assess the effects of viscosupplementation in the treatment of OA of the knee. The products were hyaluronan and hylan derivatives (Adant, Arthrum H, Artz (Artzal, Supartz), BioHy (Arthrease, Euflexxa, Nuflexxa), Durolane, Fermathron, Go-On, Hyalgan, Hylan G-F 20 (Synvisc Hylan G-F 20), Hyruan, NRD-101 (Suvenyl), Orthovisc, Ostenil, Replasyn, SLM-10, Suplasyn, Synject and Zeel compositum). Search methods: MEDLINE (up to January (week 1) 2006 for update), EMBASE, PREMEDLINE, Current Contents up to July 2003, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched. Specialised journals and reference lists of identified randomised controlled trials (RCTs) and pertinent review articles up to December 2005 were handsearched. Selection criteria: RCTs of viscosupplementation for the treatment of people with a diagnosis of OA of the knee were eligible. Single and double-blinded studies, placebo-based and comparative studies were eligible. At least one of the four OMERACT III core set outcome measures had to be reported (Bellamy 1997). Data collection and analysis: Each trial was assessed independently by two reviewers for its methodological quality using a validated tool. All data were extracted by one reviewer and verified by a second reviewer. Continuous outcome measures were analysed as weighted mean differences (WMD) with 95% confidence intervals (CI). However, where different scales were used to measure the same outcome, standardized mean differences (SMD) were used. Dichotomous outcomes were analyzed by relative risk (RR). Main results: Seventy-six trials with a median quality score of 3 (range 1 to 5) were identified. Follow-up periods varied between day of last injection and eighteen months. Forty trials included comparisons of hyaluronan/hylan and placebo (saline or arthrocentesis), ten trials included comparisons of intra-articular (IA) corticosteroids, six trials included comparisons of nonsteroidal anti-inflammatory drugs (NSAIDs), three trials included comparisons of physical therapy, two trials included comparisons of exercise, two trials included comparisons of arthroscopy, two trials included comparisons of conventional treatment, and fifteen trials included comparisons of other hyaluronans/hylan. The pooled analyses of the effects of viscosupplements against 'placebo' controls generally supported the efficacy of this class of intervention. In these same analyses, differential efficacy effects were observed for different products on different variables and at different timepoints. Of note is the 5 to 13 week post injection period which showed a percent improvement from baseline of 28 to 54% for pain and 9 to 32% for function. In general, comparable efficacy was noted against NSAIDs and longer-term benefits were noted in comparisons against IA corticosteroids. In general, few adverse events were reported in the hyaluronan/hylan trials included in these analyses. Authors' conclusions: Based on the aforementioned analyses, viscosupplementation is an effective treatment for OA of the knee with beneficial effects: on pain, function and patient global assessment; and at different post injection periods but especially at the 5 to 13 week post injection period. It is of note that the magnitude of the clinical effect, as expressed by the WMD and standardised mean difference (SMD) from the RevMan 4.2 output, is different for different products, comparisons, timepoints, variables and trial designs. However, there are few randomised head-to-head comparisons of different viscosupplements and readers should be cautious, therefore, in drawing conclusions regarding the relative value of different products. The clinical effect for some products, against placebo, on some variables at some timepoints is in the moderate to large effect-size range. Readers should refer to relevant tables to review specific detail given the heterogeneity in effects across the product class and some discrepancies observed between the RevMan 4.2 analyses and the original publications. Overall, the analyses performed are positive for the HA class and particularly positive for some products with respect to certain variables and timepoints, such as pain on weight bearing at 5 to 13 weeks postinjection. In general, sample-size restrictions preclude any definitive comment on the safety of the HA class of products; however, within the constraints of the trial designs employed no major safety issues were detected. In some analyses viscosupplements were comparable in efficacy to systemic forms of active intervention, with more local reactions but fewer systemic adverse events. In other analyses HA products had more prolonged effects than IA corticosteroids. Overall, the aforementioned analyses support the use of the HA class of products in the treatment of knee OA.
BACKGROUND: Osteoarthritis of the knee affects up to 10% of the elderly population. The condition is frequently treated by intra-articular injection of hyaluronic acid. We performed a systematic review and meta-analysis of randomized controlled trials to assess the effectiveness of this treatment.
METHODS: We searched MEDLINE, EMBASE, CINAHL, BIOSIS and the Cochrane Controlled Trial Register from inception until April 2004 using a combination of search terms for knee osteoarthritis and hyaluronic acid and a filter for randomized controlled trials. We extracted data on pain at rest, pain during or immediately after movement, joint function and adverse events.
RESULTS: Twenty-two trials that reported usable quantitative information on any of the predefined end points were identified and included in the systematic review. Even though pain at rest may be improved by hyaluronic acid, the data available from these studies did not allow an appropriate assessment of this end point. Patients who received the intervention experienced a reduction in pain during movement: the mean difference on a 100-mm visual analogue scale was -3.8 mm (95% confidence interval [CI] -9.1 to 1.4 mm) after 2-6 weeks, -4.3 mm (95% CI -7.6 to -0.9 mm) after 10-14 weeks and -7.1 mm (95% CI -11.8 to -2.4 mm) after 22-30 weeks. However, this effect was not compatible with a clinically meaningful difference (expected to be about 15 mm on the visual analogue scale). Furthermore, the effect was exaggerated by trials not reporting an intention-to-treat analysis. No improvement in knee function was observed at any time point. Even so, the effect of hyaluronic acid on knee function was more favourable when allocation was not concealed. Adverse events occurred slightly more often among patients who received the intervention (relative risk 1.08, 95% CI 1.01 to 1.15). Only 4 trials explicitly reported allocation concealment, had blinded outcome assessment and presented intention-to-treat data.
INTERPRETATION: According to the currently available evidence, intra-articular hyaluronic acid has not been proven clinically effective and may be associated with a greater risk of adverse events. Large trials with clinically relevant and uniform end points are necessary to clarify the benefit-risk ratio.
BACKGROUND: The magnitude of the therapeutic effects of intra-articular injection of hyaluronic acid on osteoarthritis of the knee is still in question. The aim of this meta-analysis was to elucidate the therapeutic efficacy and safety of intra-articular injection of hyaluronic acid for osteoarthritis of the knee. METHODS: We conducted a meta-analysis of twenty blinded randomized controlled trials that compared the therapeutic effect of intra-articular injection of hyaluronic acid with that of intra-articular injection of a placebo to treat osteoarthritis of the knee. The outcome end points were classified into three categories: pain with activities, pain without activities, and function. The outcome measures of the efficacy of hyaluronic acid were the mean differences in the efficacy scores between the hyaluronic acid and placebo groups. The outcome measure of the safety of hyaluronic acid was the relative risk of adverse events. RESULTS: Intra-articular injection of hyaluronic acid can decrease symptoms of osteoarthritis of the knee. We found significant improvements in pain and functional outcomes with few adverse events. However, there was significant between-study heterogeneity in the estimates of the efficacy of hyaluronic acid. Subgroup analysis and meta-regression analysis showed that lower methodological quality such as a single-blind or single-center design resulted in higher estimates of hyaluronic acid efficacy, that introduction of acetaminophen as an escape analgesic in the trial resulted in lower estimates of hyaluronic acid efficacy, and that patients older than sixty-five years of age and those with the most advanced radiographic stage of osteoarthritis (complete loss of the joint space) were less likely to benefit from intra-articular injection of hyaluronic acid. CONCLUSIONS: This meta-analysis confirmed the therapeutic efficacy and safety of intra-articular injection of hyaluronic acid for the treatment of osteoarthritis of the knee. Additional well-designed randomized controlled trials with high methodological quality are needed to resolve the continued uncertainty about the therapeutic effects of different types of hyaluronic acid products on osteoarthritis of the knee in various clinical situations and patient populations. Level of Evidence: Therapeutic study, Level II-3b (systematic review; nonhomogeneous Level-I studies). See Instructions to Authors for a complete description of levels of evidence.
