A meta-analysis of antidepressant outcome under "blinder" conditions

Psychological therapies versus pharmacological interventions for panic disorder with or without agoraphobia in adults

BACKGROUND

Panic disorder is common and deleterious to mental well-being. Psychological therapies and pharmacological interventions are both used as treatments for panic disorder with and without agoraphobia. However, there are no up-to-date reviews on the comparative efficacy and acceptability of the two treatment modalities, and such a review is necessary for improved treatment planning for this disorder.

OBJECTIVES

To assess the efficacy and acceptability of psychological therapies versus pharmacological interventions for panic disorder, with or without agoraphobia, in adults.

SEARCH METHODS

We searched the Cochrane Common Mental Disorders Group Specialised Register on 11 September 2015. This register contains reports of relevant randomised controlled trials from the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1950 to present), Embase (1974 to present), and PsycINFO (1967 to present). We cross-checked reference lists of relevant papers and systematic reviews. We did not apply any restrictions on date, language, or publication status.

SELECTION CRITERIA

We included all randomised controlled trials comparing psychological therapies with pharmacological interventions for panic disorder with or without agoraphobia as diagnosed by operationalised criteria in adults.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and resolved any disagreements in consultation with a third review author. For dichotomous data, we calculated risk ratios (RR) with 95% confidence intervals (CI). We analysed continuous data using standardised mean differences (with 95% CI). We used the random-effects model throughout.

MAIN RESULTS

We included 16 studies with a total of 966 participants in the present review. Eight of the studies were conducted in Europe, four in the USA, two in the Middle East, and one in Southeast Asia.None of the studies reported long-term remission/response (long term being six months or longer from treatment commencement).There was no evidence of a difference between psychological therapies and selective serotonin reuptake inhibitors (SSRIs) in terms of short-term remission (RR 0.85, 95% CI 0.62 to 1.17; 6 studies; 334 participants) or short-term response (RR 0.97, 95% CI 0.51 to 1.86; 5 studies; 277 participants) (very low-quality evidence), and no evidence of a difference between psychological therapies and SSRIs in treatment acceptability as measured using dropouts for any reason (RR 1.33, 95% CI 0.80 to 2.22; 6 studies; 334 participants; low-quality evidence).There was no evidence of a difference between psychological therapies and tricyclic antidepressants in terms of short-term remission (RR 0.82, 95% CI 0.62 to 1.09; 3 studies; 229 participants), short-term response (RR 0.75, 95% CI 0.51 to 1.10; 4 studies; 270 participants), or dropouts for any reason (RR 0.83, 95% CI 0.53 to 1.30; 5 studies; 430 participants) (low-quality evidence).There was no evidence of a difference between psychological therapies and other antidepressants in terms of short-term remission (RR 0.90, 95% CI 0.48 to 1.67; 3 studies; 135 participants; very low-quality evidence) and evidence that psychological therapies did not significantly increase or decrease the short-term response over other antidepressants (RR 0.96, 95% CI 0.67 to 1.37; 3 studies; 128 participants) or dropouts for any reason (RR 1.55, 95% CI 0.91 to 2.65; 3 studies; 180 participants) (low-quality evidence).There was no evidence of a difference between psychological therapies and benzodiazepines in terms of short-term remission (RR 1.08, 95% CI 0.70 to 1.65; 3 studies; 95 participants), short-term response (RR 1.58, 95% CI 0.70 to 3.58; 2 studies; 69 participants), or dropouts for any reason (RR 1.12, 95% CI 0.54 to 2.36; 3 studies; 116 participants) (very low-quality evidence).There was no evidence of a difference between psychological therapies and either antidepressant alone or antidepressants plus benzodiazepines in terms of short-term remission (RR 0.86, 95% CI 0.71 to 1.05; 11 studies; 663 participants) and short-term response (RR 0.95, 95% CI 0.76 to 1.18; 12 studies; 800 participants) (low-quality evidence), and there was no evidence of a difference between psychological therapies and either antidepressants alone or antidepressants plus benzodiazepines in terms of treatment acceptability as measured by dropouts for any reason (RR 1.08, 95% CI 0.77 to 1.51; 13 studies; 909 participants; very low-quality evidence). The risk of selection bias and reporting bias was largely unclear. Preplanned subgroup and sensitivity analyses limited to trials with longer-term, quality-controlled, or individual psychological therapies suggested that antidepressants might be more effective than psychological therapies for some outcomes.There were no data to contribute to a comparison between psychological therapies and serotonin-norepinephrine reuptake inhibitors (SNRIs) and subsequent adverse effects.

AUTHORS' CONCLUSIONS

The evidence in this review was often imprecise. The superiority of either therapy over the other is uncertain due to the low and very low quality of the evidence with regard to short-term efficacy and treatment acceptability, and no data were available regarding adverse effects.The sensitivity analysis and investigation of the sources of heterogeneity indicated three possible influential factors: quality control of psychological therapies, the length of intervention, and the individual modality of psychological therapies.Future studies should examine the long-term effects after intervention or treatment continuation and should provide information on risk of bias, especially with regard to selection and reporting biases.

Blindness and bias in a trial of antidepressant medication for chronic tension-type headache

This study aimed to examine penetration of the blind in a randomized, placebo-controlled trial. Neurologists' ratings of improvement and medication side-effects, participants' ratings of improvement and daily diary recordings of headaches were assessed along with participants' and neurologists' guesses about treatment group placement in participants who completed at least 3 months of treatment (N = 169). Despite blinding, treating neurologists successfully identified the medication condition for 82% of participants receiving medication only; trial participants accurately identified their medication condition when receiving active medication (77% of participants), but not when receiving placebo. Concurrent stress-management therapy reduced, but did not eliminate penetration of the blind. Irrespective of drug condition, when participants were improved they were judged to be on active medication and when unimproved they were judged to be on placebo. However, neurologists' ratings of improvement, participants' reports of improvement and daily headache recordings yielded equivalent outcomes. Penetration of the blind needs to be assessed, not assumed in clinical trials in headache. However, penetration of the blind did not produce a prodrug bias as has been asserted by critics. Better methods of assessing and quantifying blindness are needed.

Active placebos versus antidepressants for depression

BACKGROUND

Although there is a consensus that antidepressants are effective in depression, placebo effects are also thought to be substantial. Side effects of antidepressants may reveal the identity of medication to participants or investigators and thus may bias the results of conventional trials using inert placebos. Using an 'active' placebo which mimics some of the side effects of antidepressants may help to counteract this potential bias.

OBJECTIVES

To investigate the efficacy of antidepressants when compared with 'active' placebos.

SEARCH STRATEGY

The Cochrane Collaboration Depression, Anxiety and Neurosis review groups's search strategy was used to search MEDLINE (1966-2000), PsychLIT (1980-2000) and EMBASE (1974-2000) and this was last done in July 2000. Reference lists from relevant articles and textbooks were searched and 12 specialist journals were handsearched up to 1996.

SELECTION CRITERIA

Randomised and quasi randomised controlled trials comparing antidepressants with active placebos in people with depression.

DATA COLLECTION AND ANALYSIS

Since many different outcome measures were used a standard measure of effect was calculated for each trial. A subgroup analysis of inpatient and outpatient trials was conducted. Two reviewers independently assessed whether each trial met inclusion criteria.

MAIN RESULTS

Nine studies involving 751 participants were included. Two of them produced effect sizes which showed a consistent and statistically significant difference in favour of the active drug. Combining all studies produced a pooled estimate of effect of 0.39 standard deviations (confidence interval, 0.24 to 0.54) in favour of the antidepressant measured by improvement in mood. There was high heterogeneity due to one strongly positive trial. Sensitivity analysis omitting this trial reduced the pooled effect to 0.17 (0.00 to 0.34). The pooled effect for inpatient and outpatient trials was highly sensitive to decisions about which combination of data was included but inpatient trials produced the lowest effects.

REVIEWER'S CONCLUSIONS

The more conservative estimates from the present analysis found that differences between antidepressants and active placebos were small. This suggests that unblinding effects may inflate the efficacy of antidepressants in trials using inert placebos. Further research into unblinding is warranted.