The trouble with antidepressants: why the evidence overplays benefits and underplays risks—an essay by John B Warren

Depression can be severe and reduce life expectancy. Antidepressant prescribing has increased substantially in recent years so that one in eight UK adults, some 7.3 million people, now receive a prescription for antidepressants each year, and many take them long term.1 More than 60% of US residents taking antidepressants do so for more than two years.2

Although meta-analyses seem to support widespread use, concerns have been raised about the effectiveness and safety of the drugs. The conclusions of meta-analyses have been criticised because of manufacturers’ influence on trials,34 under-recognition of the placebo effect, inadequate attention to negative data, different methods used to assess risk and benefit, and lack of benefit on suicide. There are also concerns about limited safety databases and the huge commercial promotion of these drugs.

Analysis of the benefits and risks of drugs in psychiatry differs from other therapeutic areas. There are no reliable biomarkers of psychiatric disease and no primary endpoint to summarise safety and efficacy (an equivalent to mortality in cardiovascular or oncology trials). Psychiatry therefore depends on composite scales for diagnosis and to assess drug efficacy. As composite measures are rarely used for adverse events, trials are likely to overestimate benefit and underestimate risks, with serious implications for public health. Although prescribers will often see patients improve over time, questions remain about how much antidepressants contribute to this and whether long term treatment is safe.