Drugmakers have responded to a headline-grabbing new study which claims that there is little reason to prescribe antidepressants to the majority of depressed patients.

A group of experts, led by Professor Irving Kirsch at the University of Hull, UK, have made the claim in a study published in the journal PLoS Medicine after a meta-analysis of both published and unpublished data from clinical trials of four blockbuster selective serotonin reuptake inhibitors – Eli Lilly’s Prozac (fluoxetine), Wyeth's Effexor (venlafaxine), GlaxoSmithKline's Paxil/Seroxat (paroxetine) and Bristol-Myers Squibb's drug Serzone (nefazodone).

The analysis showed that in comparison to placebo effects, antidepressants do not have clinically significant effects in mildly depressed patients or in most patients who suffer from very severe depression. Furthermore, it is claimed that the apparent clinical effectiveness of antidepressants in the small group of extremely depressed patients is somewhat distorted. The seemingly good result came from fact that these patients’ response to the placebo decreased, rather than any notable increase in their response to antidepressants, the authors say.

Prof Kirsch said: “The difference in improvement between patients taking placebos and patients taking antidepressants is not very great. This means that depressed people can improve without chemical treatments”. He added that the study “raises serious issues that need to be addressed surrounding drug licensing and how drug trial data is reported”.

However a spokeswoman for GSK said that the authors have “failed to acknowledge the very positive benefit these treatments have provided to patients and their families who are dealing with depression and they are at odds with what has been seen in actual clinical practice". She added that the study “only examined a small subset of the total data available, while regulatory bodies around the world have conducted extensive reviews and evaluations of all of the data available". Lilly echoed this sentiment, saying that "extensive scientific and medical experience” has demonstrated that Prozac is an effective anti-depressant.

Nevertheless, Marjorie Wallace of Sane told the BBC that if the Hull results were upheld in further studies, “they would be very disturbing”. She added that “the newer anti-depressants were the great hope for the future” but “these findings could remove what has been seen as a vital choice for thousands in treating what can be a life-threatening condition”.