When compared to placebo there was proof that in acute treatment more patients experienced an improvement of depression when they were treated with mirtazapine. The prospect of a total cure was no better in the mirtazapine group than in the placebo group. However, this aspect was only investigated in 1 trial for mirtazapine. In numerous comparisons with other antidepressants, mirtazapine did not show proof of superiority. In addition, it was shown that patients treated with mirtazapine discontinued treatment more often due to side effects (adverse events) than patients treated with placebo or with some of the other antidepressants.
Bupropion: symptoms completely disappear in some patients
The search identified 7 trials on bupropion XL and the Institute was given access to the complete clinical study reports by manufacturers. There was proof of benefit for this agent compared to placebo in acute therapy and in the prevention of relapse into seasonal affective disorder. In some patients, the symptoms were reduced so much that they no longer met the criteria for a diagnosis of depression (remission). Moreover, the data provided no indications of harm.
The only antidepressant that was compared with bupropion XL in trials was venlafaxine XR. Bupropion XL showed inferiority to venlafaxine XR in acute therapy. Further information can be found in the executive summary of the final report (see below).
Obligation to publish trial results must be legally enforceable
As has been revealed in the process of preparing this report, a lack of willingness to cooperate on the part of the manufacturers leads to benefit evaluations of limited validity and causes considerable delays in producing assessments. "Deception through concealment of trial data is no trivial offence", says IQWiG's director, Peter Sawicki. "The study sponsors are depriving patients and doctors of the opportunity to make an informed decision on different therapy options. As the example of reboxetine shows, concealing trial data can lead to patients receiving a drug, for which there is not only no proof of benefit, but which can also cause harm." Moreover, it is not only the work of the Institute that is hindered, but also that of the G-BA. According to the Institute's director, "The G-BA then lacks the reliable scientific basis that it needs for its decisions on reimbursement of drugs." IQWiG's position on this issue is described in a second press release (see below).
Reboxetine was approved in Germany in December 1997. For its part, however, the German drug regulatory authority could not consider all the trials that IQWiG had analysed, because IQWiG's report also includes trials that were completed after 1997. Pfizer also applied for approval in the USA but this was evidently not granted in 2001.
Source: Institute for Quality and Efficiency in Health Care