Placebo Response and Media Attention in Randomized Clinical Trials Assessing Cannabis-Based Therapies for Pain: A Systematic Review and Meta-analysis.

Importance: Persistent pain is a common and disabling health problem that is often difficult to treat. There is an increasing interest in medicinal cannabis for treatment of persistent pain; however, the limited superiority of cannabinoids over placebo in clinical trials suggests that positive expectations may contribute to the improvements. Objective: To evaluate the size of placebo responses in randomized clinical trials in which cannabinoids were compared with placebo in the treatment of pain and to correlate these responses to objective estimates of media attention. Data Sources: A systematic literature search was conducted within the MEDLINE and Embase databases. Studies published until September 2021 were considered. Study Selection: Cannabinoid studies with a double-blind, placebo-controlled design with participants 18 years or older with clinical pain of any duration were included. Studies were excluded if they treated individuals with HIV/AIDS or severe skin disorders. Data Extraction and Synthesis: The study followed the Preferred Reporting Items for Systematic Review and Meta-analyses reporting guideline. Data were extracted by independent reviewers. Quality assessment was performed using the Risk of Bias 2 tool. Attention and dissemination metrics for each trial were extracted from Altmetric and Crossref. Data were pooled and analyzed using a random-effects statistical model. Main Outcomes and Measures: Change in pain intensity from before to after treatment, measured as bias-corrected standardized mean difference (Hedges g). Results: Twenty studies, including 1459 individuals (mean [SD] age, 51 [7] years; age range, 33-62 years; 815 female [56%]), were included. Pain intensity was associated with a significant reduction in response to placebo, with a moderate to large effect size (mean [SE] Hedges g, 0.64 [0.13]; P < .001). Trials with low risk of bias had greater placebo responses (q1 = 5.47; I2 = 87.08; P = .02). The amount of media attention and dissemination linked to each trial was proportionally high, with a strong positive bias, but was not associated with the clinical outcomes. Conclusions and Relevance: Placebo contributes significantly to pain reduction seen in cannabinoid clinical trials. The positive media attention and wide dissemination may uphold high expectations and shape placebo responses in future trials, which has the potential to affect the outcome of clinical trials, regulatory decisions, clinical practice, and ultimately patient access to cannabinoids for pain relief.

Effectiveness, costs and cost-effectiveness of chiropractic care and physiotherapy compared with information and advice in the treatment of non-specific chronic low back pain: study protocol for a randomised controlled trial.

BACKGROUND: Low back pain is a global public health problem and a leading cause of disability all over the world. The lifetime prevalence of low back pain is 70-80% and a significant proportion of people affected develop chronic low back pain (CLBP). Besides a severe negative impact on people's health and health-related quality of life, CLBP is associated with substantial costs for society. Medical costs for the management of CLBP and costs for production losses due to absenteeism from work are sizeable. Pharmaceuticals, physical activity, manipulation, and multidisciplinary rehabilitation interventions are examples of widely used treatments for CLBP. However, the scientific basis to recommend the use of one treatment over another is limited and more research is needed to study the effects, costs and cost-effectiveness of treatments for CLBP in clinical practice. The aim of the study is to evaluate the effectiveness (back pain-related functional limitation, back pain intensity, general health, health-related quality of life, and working status), costs (medical costs and costs for production losses) and cost-effectiveness of chiropractic care and physiotherapy when added to information and advice in the treatment of patients with non-specific CLBP in Sweden. METHODS/DESIGN: This is a pragmatic randomised controlled trial, where participants are recruited through six primary care rehabilitation units (PCRUs) in Stockholm County Council, Sweden. Individuals with non-specific CLBP are individually randomised to one of four treatment groups: 'information and advice'; 'physiotherapy, and information and advice'; 'chiropractic care, and information and advice'; or 'chiropractic care, physiotherapy, and information and advice'. A sample size of 600 participants will be recruited during a period of 33 months. A computer-based questionnaire is used to collect data on back pain-related functional limitation (Oswestry Disability Index), pain intensity (Numeric Rating Scale), general health (self-rated health), health-related quality of life (EQ-5D-3L), and working status (measured as percentage of full-time work). Data will be collected at baseline, and at 3, 6, and 12 months after baseline. DISCUSSION: The results from our study should be considered when producing evidence-based guidelines and recommendations on which treatment strategies to use for CLBP. TRIAL REGISTRATION: ISRCTN registry, ID: ISRCTN15830360 . Registered prospectively on 2 February 2017.