Do randomized clinical trials with inadequate blinding report enhanced placebo effects for intervention groups and nocebo effects for placebo groups? A protocol for a meta-epidemiological study of PDE-5 inhibitors

Effects of mindfulness-based stress reduction on adults with sleep disturbance: an updated systematic review and meta-analysis

OBJECTIVE

Mindfulness-based stress reduction (MBSR) is a meditation-based therapy originally recommended for stress management. However, it is currently used to alleviate sleep disturbances. Therefore, this contemporary systematic review aimed to elucidate the clinical effects of MBSR on sleep quality and sleep-related daytime impairment in adults with sleep disturbances, including chronic insomnia disorders.

DESIGN

Systematic review and meta-analysis of randomised controlled trials (RCTs).

METHODS

A comprehensive search was conducted using the following databases: Ovid MEDLINE, AMED, Ovidembase, PsycINFO, Cochrane Library, CINAHL, and four domestic databases: KoreaMed, KISS, KMbase and NDSL. The final search update was performed in June 2022. Two researchers independently selected relevant studies, assessed the risk of bias and extracted the data.

RESULTS

Of the 7516 records searched, 20 RCTs and 21 reports were included. In the subgroup analysis, MBSR did not improve objective or subjective sleep quality in chronic insomnia and cancers. However, MBSR versus waitlist control might have been effective in improving subjective sleep quality, but with substantial heterogeneity (standardised mean difference=-0.32; 95% CI: -0.56 to -0.08; I²=71%). In addition, MBSR compared with active control did not improve the sleep-related daytime impairments including depression, anxiety, stress, fatigue and quality of life. The overall risk of bias included in this review was a concern because of performance and detection bias.

CONCLUSIONS

MBSR might be ineffective for improving sleep quality in patients with chronic insomnia and cancers. In addition, more than half of the RCTs included in this review had small sample sizes and were vulnerable to performance and detection biases. Therefore, well-designed RCTs with larger sample sizes are required to confirm the clinical effects of MBSR in adults with sleep disturbances.

PROSPERO REGISTRATION NUMBER

CRD42015027963.

The response-time relationship and covariate effects of acupuncture for chronic pain: A systematic review and model-based longitudinal meta-analysis

BACKGROUND AND OBJECTIVE

Critical clinical questions regarding how soon and how long the analgesic effect will be achieved by acupuncture, as well as who will be responsive to acupuncture, need further address. The aim of the study was to investigate the response-time relationship and covariate effects of acupuncture.

DATABASES AND DATA TREATMENT

PubMed and EMBASE were searched up to December 2018 for randomized controlled trials that involved sham acupuncture, true acupuncture and conventional therapy. We used a model-based longitudinal meta-analysis to characterize the response-time profile of these treatments.

RESULTS

Seventy-seven randomized clinical trials involved chronic shoulder, neck, knee and low back pain were included. The response-time analysis suggested that the treatment duration of acupuncture will be 5 weeks or more to achieve 80% of maximum analgesic effect. Moreover a lower baseline pain intensity and the location of low back pain resulted in a lower pain relief of acupuncture intervention. The absolute maximum analgesic effects of sham acupuncture and conventional therapy were 22.6 and 15.8 points at a 0-100 NRS scale. The absolute effect of true acupuncture was 26.1 points for low back pain (relative effect of 3.5 and 9.4 points to sham and conventional therapy), 34.9 points for other pain body locations (relative effect of 12.3 and 19.1 points to sham and conventional therapy), in patients with a baseline pain intensity of 60 points.

CONCLUSION

The treatment duration of acupuncture will not be less than 5 weeks to achieve 80% maximum analgesic effect. Higher analgesic effect was related to higher baseline pain intensity and pain location of neck, shoulder and knee.

SIGNIFICANCE

Our systematic review and meta-analysis provides the clear evidence for the treatment duration and significant related covariates of acupuncture intervention for chronic pain. These results provide useful suggestion for acupuncture intervention in clinical pain management.

Empirical Evidence of Study Design Biases in Randomized Trials: Systematic Review of Meta-Epidemiological Studies

OBJECTIVE

To synthesise evidence on the average bias and heterogeneity associated with reported methodological features of randomized trials.

DESIGN

Systematic review of meta-epidemiological studies.

METHODS

We retrieved eligible studies included in a recent AHRQ-EPC review on this topic (latest search September 2012), and searched Ovid MEDLINE and Ovid EMBASE for studies indexed from Jan 2012-May 2015. Data were extracted by one author and verified by another. We combined estimates of average bias (e.g. ratio of odds ratios (ROR) or difference in standardised mean differences (dSMD)) in meta-analyses using the random-effects model. Analyses were stratified by type of outcome ("mortality" versus "other objective" versus "subjective"). Direction of effect was standardised so that ROR < 1 and dSMD < 0 denotes a larger intervention effect estimate in trials with an inadequate or unclear (versus adequate) characteristic.

RESULTS

We included 24 studies. The available evidence suggests that intervention effect estimates may be exaggerated in trials with inadequate/unclear (versus adequate) sequence generation (ROR 0.93, 95% CI 0.86 to 0.99; 7 studies) and allocation concealment (ROR 0.90, 95% CI 0.84 to 0.97; 7 studies). For these characteristics, the average bias appeared to be larger in trials of subjective outcomes compared with other objective outcomes. Also, intervention effects for subjective outcomes appear to be exaggerated in trials with lack of/unclear blinding of participants (versus blinding) (dSMD -0.37, 95% CI -0.77 to 0.04; 2 studies), lack of/unclear blinding of outcome assessors (ROR 0.64, 95% CI 0.43 to 0.96; 1 study) and lack of/unclear double blinding (ROR 0.77, 95% CI 0.61 to 0.93; 1 study). The influence of other characteristics (e.g. unblinded trial personnel, attrition) is unclear.

CONCLUSIONS

Certain characteristics of randomized trials may exaggerate intervention effect estimates. The average bias appears to be greatest in trials of subjective outcomes. More research on several characteristics, particularly attrition and selective reporting, is needed.

The nocebo effect of drugs

While the placebo effect has been studied for a long time, much less is known about its negative counterpart, named the nocebo effect. However, it may be of particular importance because of its impact on the treatment outcomes and public health. We conducted a review on the nocebo effect using PubMed and other databases up to July 2014. The nocebo effect refers by definition to the induction or the worsening of symptoms induced by sham or active therapies. Examples are numerous and concerns both clinical trials and daily practice. The underlying mechanisms are, on one hand, psychological (conditioning and negative expectations) and, on the other hand, neurobiological (role of cholecystokinin, endogenous opioids and dopamine). Nocebo effects can modulate the outcome of a given therapy in a negative way, as do placebo effects in a positive way. The verbal and nonverbal communications of physicians contain numerous unintentional negative suggestions that may trigger a nocebo response. This raises the important issue of how physicians can at the same time obtain informed consent and minimize nocebo-related risks. Every physician has to deal with this apparent contradiction between primum non nocere and to deliver truthful information about risks. Meticulous identification of patients at risk, information techniques such as positive framing, contextualized informed consent, and even noninformation, is valuable.

Do randomized clinical trials with inadequate blinding report enhanced placebo effects for intervention groups and nocebo effects for placebo groups?

BACKGROUND

Studies suggest that expectations powerfully shape clinical outcomes. For subjective outcomes in adequately blinded trials, health improvements are substantial and largely explained by non-specific factors.The objective of this study was to investigate if unblinding in randomized controlled trials (RCTs) is associated with enhanced placebo effects for intervention groups and nocebo effects for placebo groups. For these effects, a secondary objective was to explore potential moderating factors.

METHODS

We included RCTs that investigated the efficacy of phosphodiesterase-5 (PDE-5) inhibitors for male erectile dysfunction by comparing one PDE-5 inhibitor to placebo. In addition, to be included studies must have reported scores for change from baseline, or baseline and final International Index of Erectile Functioning-Erectile Functioning domain score (IIEF-EF), and be published in either English, French, Dutch, or German.We searched for both published and unpublished relevant trials using PUBMED, EMBASE, the Cochrane Central Register of Controlled Trials, a clinical trials register (clinicaltrials.gov) and the Food and Drug Administration clinical reviews through March 2012.We evaluated the blinding status of trials with the Cochrane Risk of Bias Tool, using the domains of allocation sequence concealment, blinding of participants, healthcare providers and outcome assessors. Across these four domains, studies that scored low risk of bias were judged to be adequately blinded and studies that scored unclear or high risk of bias were judged to be inadequately blinded.

RESULTS

We included 110 studies (205 journal publications and 2 unpublished sources) that involved 23,877 participants; 93 (85%), 51 (46%), 93 (85%) and 93 (85%) studies were assessed with an unclear risk of bias for allocation concealment, blinding of participant, blinding of caregiver and blinding of outcome assessor, respectively. None of the studies reported testing of blinding.None of the 205 journal publications provided sufficient details to assess allocation concealment, blinding of participants, caregivers and outcome assessors. After contacting authors for additional information, we judged five studies to be adequately (n = 1,202) and 16 to be inadequately (n = 3,006) blinded. The IIEF-EF score for placebo groups in adequately blinded trials versus inadequately blinded trials was 1.92 points (95% CI, 0.64 to 3.20) versus 1.56 (95% CI, 0.93 to 2.20), respectively. The IIEF-EF score for intervention groups in adequately blinded trials versus inadequately blinded trials was 9.40 (95% CI, 6.96 to 11.83) versus 8.33 (95% CI, 7.29 to 9.37), respectively. In a secondary analysis, prior experience with the drug affected the scores; in placebo groups with participants naïve to the intervention the score was 2.89 (95% CI, 2.33 to 3.45) versus -0.11 (95% CI, -2.06 to 1.84) with participants having prior experience. In the intervention groups, these scores were 7.99 (95% CI, 6.85 to 9.14) versus 8.33 (95% CI, 7.51 to 9.16), respectively.Unblinding lowered placebo scores (creating a nocebo effect) by 19% (0.33 points; 95% CI, -0.96 to 1.62). Unblinding lowered intervention scores by 11% (1.0; 95% CI, -1.35 to 3.47). The results provided no conclusive evidence for nocebo or enhanced placebo effects. Patients taking a PDE-5 inhibitor for the first time experience a larger placebo effect that accounts for 35% of the total effect.

CONCLUSIONS

Given the overall poor reporting of blinding in clinical trial reports and the small number of trials that could be rated as adequately or inadequately blinded, we could not draw any robust conclusions about the existence or absence of nocebo and enhanced placebo effects. A large placebo effect was found for patients taking PDE-5 inhibitors for the first time. It was not clear if previous exposure to the drug impacted trial blinding.We found clear evidence that studies assessing a subjective continuous outcome fail to report on measures taken to secure double blinding. Although we observed a trend for the presence of a nocebo effect, there was insufficient evidence to quantify its impact on expectations. RCTs with patients with no prior experience with PDE-5 inhibitors reported larger placebo effects and possibly these studies were better blinded. Future research should further investigate the factors that contribute to blinding and their impact on health outcomes in randomized trials of subjectively assessed conditions. This research is part of a PhD project and has no external funding. The authors have no competing interests to declare.

An empirical investigation of the potential impact of selective inclusion of results in systematic reviews of interventions: study protocol

BACKGROUND

Systematic reviewers may encounter a multiplicity of outcome data in the reports of randomised controlled trials included in the review (for example, multiple measurement instruments measuring the same outcome, multiple time points, and final and change from baseline values). The primary objectives of this study are to investigate in a cohort of systematic reviews of randomised controlled trials of interventions for rheumatoid arthritis, osteoarthritis, depressive disorders and anxiety disorders: (i) how often there is multiplicity of outcome data in trial reports; (ii) the association between selection of trial outcome data included in a meta-analysis and the magnitude and statistical significance of the trial result, and; (iii) the impact of the selection of outcome data on meta-analytic results.

METHODS/DESIGN

Forty systematic reviews (20 Cochrane, 20 non-Cochrane) of RCTs published from January 2010 to January 2012 and indexed in the Cochrane Database of Systematic Reviews (CDSR) or PubMed will be randomly sampled. The first meta-analysis of a continuous outcome within each review will be included. From each review protocol (where available) and published review we will extract information regarding which types of outcome data were eligible for inclusion in the meta-analysis (for example, measurement instruments, time points, analyses). From the trial reports we will extract all outcome data that are compatible with the meta-analysis outcome as it is defined in the review and with the outcome data eligibility criteria and hierarchies in the review protocol. The association between selection of trial outcome data included in a meta-analysis and the magnitude and statistical significance of the trial result will be investigated. We will also investigate the impact of the selected trial result on the magnitude of the resulting meta-analytic effect estimates.

DISCUSSION

The strengths of this empirical study are that our objectives and methods are pre-specified and transparent. The results may inform methods guidance for systematic review conduct and reporting, particularly for dealing with multiplicity of randomised controlled trial outcome data.