Effects of drop-out on efficacy estimates in five Cochrane reviews of popular antipsychotics for schizophrenia

Risperidone versus placebo for schizophrenia

BACKGROUND

Risperidone is the first new-generation antipsychotic drug made available in the market in its generic form.

OBJECTIVES

To determine the clinical effects, safety and cost-effectiveness of risperidone compared with placebo for treating schizophrenia.

SEARCH METHODS

On 19th October 2015, we searched the Cochrane Schizophrenia Group Trials Register, which is based on regular searches of CINAHL, BIOSIS, AMED, EMBASE, PubMed, MEDLINE, PsycINFO, and registries of clinical trials. We checked the references of all included studies and contacted industry and authors of included studies for relevant studies and data.

SELECTION CRITERIA

Randomised clinical trials (RCTs) comparing oral risperidone with placebo treatments for people with schizophrenia and/or schizophrenia-like psychoses.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies, assessed the risk of bias of included studies and extracted data. For dichotomous data, we calculated the risk ratio (RR), and the 95% confidence interval (CI) on an intention-to-treat basis. For continuous data, we calculated mean differences (MD) and the 95% CI. We created a 'Summary of findings table' using GRADE (Grading of Recommendations Assessment, Development and Evaluation).

MAIN RESULTS

The review includes 15 studies (N = 2428). Risk of selection bias is unclear in most of the studies, especially concerning allocation concealment. Other areas of risk such as missing data and selective reporting also caused some concern, although not affected on the direction of effect of our primary outcome, as demonstrated by sensitivity analysis. Many of the included trials have industry sponsorship of involvement. Nonetheless, generally people in the risperidone group are more likely to achieve a significant clinical improvement in mental state (6 RCTs, N = 864, RR 0.64, CI 0.52 to 0.78, very low-quality evidence). The effect withstood, even when three studies with >50% attrition rate were removed from the analysis (3 RCTs, N = 589, RR 0.77, CI 0.67 to 0.88). Participants receiving placebo were less likely to have a clinically significant improvement on Clinical Global Impression scale (CGI) than those receiving risperidone (4 RCTs, N = 594, RR 0.69, CI 0.57 to 0.83, very low-quality evidence). Overall, the risperidone group was 31% less likely to leave early compared to placebo group (12 RCTs, N = 2261, RR 0.69, 95% CI 0.62 to 0.78, low-quality evidence), but Incidence of significant extrapyramidal side effect was more likely to occur in the risperidone group (7 RCTs, N = 1511, RR 1.56, 95% CI 1.13 to 2.15, very low-quality evidence).When risperidone and placebo were augmented with clozapine, there is no significant differences between groups for clinical response as defined by a less than 20% reduction in PANSS/BPRS scores (2 RCTs, N = 98, RR 1.15, 95% CI 0.93 to 1.42, low-quality evidence) and attrition (leaving the study early for any reason) (3 RCTs, N = 167, RR 1.13, 95% CI 0.53 to 2.42, low quality evidence). One study measured clinically significant responses using the CGI, no effect was evident (1 RCT, N = 68, RR 1.12 95% CI 0.87 to 1.44, low quality evidence). No data were available for extrapyramidal adverse effects.

AUTHORS' CONCLUSIONS

Based on low quality evidence, risperidone appears to be benefitial in improving mental state compared with placebo, but it also causes more adverse events. Eight out of the 15 included trials were funded by pharmaceutical companies. The currently available evidence isvery low to low quality.

Shared treatment decision-making and empowerment-related outcomes in psychosis: systematic review and meta-analysis

BACKGROUND

In the UK almost 60% of people with a diagnosis of schizophrenia who use mental health services say they are not involved in decisions about their treatment. Guidelines and policy documents recommend that shared decision-making should be implemented, yet whether it leads to greater treatment-related empowerment for this group has not been systematically assessed.

AIMS

To examine the effects of shared decision-making on indices of treatment-related empowerment of people with psychosis.

METHOD

We conducted a systematic review and meta-analysis of randomised controlled trials (RCTs) of shared decision-making concerning current or future treatment for psychosis (PROSPERO registration CRD42013006161). Primary outcomes were indices of treatment-related empowerment and objective coercion (compulsory treatment). Secondary outcomes were treatment decision-making ability and the quality of the therapeutic relationship.

RESULTS

We identified 11 RCTs. Small beneficial effects of increased shared decision-making were found on indices of treatment-related empowerment (6 RCTs; g = 0.30, 95% CI 0.09-0.51), although the effect was smaller if trials with >25% missing data were excluded. There was a trend towards shared decision-making for future care leading to reduced use of compulsory treatment over 15-18 months (3 RCTs; RR = 0.59, 95% CI 0.35-1.02), with a number needed to treat of approximately 10 (95% CI 5-∞). No clear effect on treatment decision-making ability (3 RCTs) or the quality of the therapeutic relationship (8 RCTs) was found, but data were heterogeneous.

CONCLUSIONS

For people with psychosis the implementation of shared treatment decision-making appears to have small beneficial effects on indices of treatment-related empowerment, but more direct evidence is required.

Prevalence and predictors of treatment dropout from physical activity interventions in schizophrenia: a meta-analysis

OBJECTIVE

Physical activity interventions have been shown to improve the health of people with schizophrenia, yet treatment dropout poses an important challenge in this population, and rates vary substantially across studies. We conducted a meta-analysis to investigate the prevalence and predictors of treatment dropout in physical activity interventions in people with schizophrenia.

METHOD

We systematically searched major electronic databases from inception until August 2015. Randomized controlled trials of physical activity interventions in people with schizophrenia reporting dropout rates were included. Two independent authors conducted searches and extracted data. Random-effects meta-analysis and meta-regression analyses were conducted.

RESULTS

In 19 studies, 594 patients with schizophrenia assigned to exercise interventions were investigated (age=37.2 years, 67.5% male, range=37.5%-100%). Trim and fill adjusted treatment dropout rate was 26.7% [95% confidence interval (CI)=19.7%-35.0%], which is more than double than in nonactive control interventions (odds ratio=2.15, 95% CI=1.29-3.58, P=.003). In the multivariate regression, qualification of the professional delivering the intervention (β=-1.06, 95% CI=-1.77 to -0.35, P=.003) moderated treatment dropout rates, while continuous supervision of physical activity approached statistical significance (P=.05).

CONCLUSIONS

Qualified professionals (e.g., physical therapists/exercise physiologists) should prescribe supervised physical activity for people with schizophrenia to enhance adherence, improve psychiatric symptoms and reduce the onset and burden of cardiovascular disease.

Quetiapine immediate release v. placebo for schizophrenia: systematic review, meta-analysis and reappraisal

BACKGROUND

Immediate-release (IR) quetiapine has been used to treat schizophrenia since 1997, although all the principal placebo-controlled trials have >50% missing outcome data. New studies with relatively lower rates of participant withdrawal have since been published.

AIMS

To assess the efficacy and adverse effects of quetiapine IR for schizophrenia, with consideration of outcome quality and clinical meaningfulness of results, and to examine the potential impact of missing data on the main efficacy findings.

METHOD

We conducted a systematic review and meta-analysis of randomised controlled trials comparing quetiapine IR and placebo (or subtherapeutic dose in relapse prevention trials) for the treatment of schizophrenia (PROSPERO registration CRD4201100165). Primary outcomes were change in overall symptoms and response rates. We also examined whether high rates of participant withdrawal (≥50%) attenuated effect sizes, and assessed the impact of making different assumptions about these people's outcomes.

RESULTS

We identified 15 relevant trials (including 2 unpublished), providing the first 12-week data for this drug and the first data on self-reported quality of life. We found quetiapine IR to have a weighted mean difference (WMD) of 6.5 points (95% CI -8.9 to -4) on Positive and Negative Syndrome Scale (PANSS) total scores, which corresponds to a standardised mean difference (SMD) of -0.33 (95% CI -0.46 to -0.21). Longer trials reported larger mean differences favouring quetiapine IR, but the overall estimate was smaller if more conservative assumptions about the outcomes of people who left the trial early were made. Approximately 21 people needed to take quetiapine IR for 1 person to experience at least a 50% improvement in PANSS score. No difference in quality of life was observed (two RCTs), although small to moderate improvements in social functioning were found (three RCTs). Quetiapine IR caused sedation and increased rates of clinically significant weight gain, but no extrapyramidal effects were observed.

CONCLUSIONS

Quetiapine IR has a small beneficial effect on overall psychotic symptoms over 2-12 weeks, but also leads to weight gain and sedation.

Declining efficacy in controlled trials of antidepressants: effects of placebo dropout

Drug-placebo differences (effect-sizes) in controlled trials of antidepressants for major depressive episodes have declined for several decades, in association with selectively increasing clinical improvement associated with placebo-treatment. As these trends require adequate explanation, we tested the hypothesis that decreasing trial-dropout rates may be an important contributor. We gathered reports of peer-reviewed, placebo-controlled trials of antidepressants (1980-2011) by computerized literature searching, and applied meta-analysis, meta-regression and multiple linear regression methods to evaluate associations of dropout rates and other factors of interest, to reporting year and reported efficacy [standardized mean drug-placebo difference (SMD) as Hedges' g-statistic]. In 56 trials meeting inclusion and exclusion criteria, we confirmed significant overall efficacy of antidepressants but declining drug-placebo contrasts over the past three decades. Among other changes, there was a corresponding increase in placebo-associated improvement with a decline in placebo-dropout rate, mainly for lack of efficacy. These effects were found only when last-observation-carried-forward (LOCF) analyses were used. Other trial-design and subject factors, including drug-responses and drug-dropout rates, were much less associated with efficacy. We propose that declining placebo-dropout rates ascribed to inefficacy combined with use of LOCF analyses led to increasing improvement in placebo-arms that contributed to declining antidepressant-placebo contrasts in controlled treatment trials since the 1980s.

Number needed to harm: its limitations in psychotropic drug safety research

Commonly used statistical measures to quantify the likelihood of an adverse drug event (ADE) from clinical trials include risk ratio; odds ratio; and number needed to harm (NNH), the reciprocal of absolute risk. This critical review focused on NNH, specifically on its limitations in controlled trials with psychotropic medication. Data for this evaluation were obtained primarily from articles in MEDLINE from 1988 to 2012. Limitations of NNH were found to include the following: a) arbitrary binary cutoffs for continuous measures, b) limited use of confidence intervals, c) limited adjustments for potential baseline confounders, d) limited adjustments for differences in dose and treatment duration, e) rare consideration of high attrition rates, f) variable use of the term harm, g) oversimplified single harm comparisons, h) frequent biased design and reporting, i) undue emphasis on less severe ADEs, j) application primarily to short-term clinical trials, and k) little or no generalizability in community practice. In sum, the NNH metric supplies very limited information on the risks of psychotropic medication. Postmarketing surveillance of community treatment populations using case-control methodology provides far more useful data on serious ADEs.