The Pharmaceutical Journal
Vol 270 No 7236 p217
15 February 2003

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The Lancet (www.thelancet.com)
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Interferons: long-term effects uncertain

The clinical effect of interferons in relapsing remitting multiple sclerosis is uncertain beyond one year, a new review indicates. Researchers say that further trials are needed to assess the long-term efficacy and side effects of these agents.

They explain that doubts remain as to the effectiveness of interferons, with continuing questions over their ability to prevent progression. In addition, questions exist as to whether their effect is sustained and whether their benefits justify their use in view of side effects and high cost.

The researchers carried out a systematic review of randomised, placebo-controlled, double-blind trials in which patients had no confounding treatments. Data from one-year follow-up was available for 667 patients, and from a two-year follow-up for 919 patients.

The risk of exacerbations during the first year of treatment appeared to be reduced by about a quarter with interferon (relative risk 0.73). However, the authors say that results at two years' follow-up are not robust and difficult to interpret because many of the patients dropped out. Hospital admissions were not reduced in patients taking interferon compared with those for patients given placebo, according to two trials. However, the authors acknowledged that more patients were now being managed as outpatients. Clinical and haematological toxic effects were greater with interferon than with placebo in all the trials and acute toxic effects adversely affected quality of life, the authors say.

They comment that although interferon is widely used in clinical practice and patients are treated for long periods, its clinical effect at one year is modest and its effect beyond this is not clear and should be investigated (Lancet 2003;361:545).