There is good evidence from randomised controlled trials that IFNB-1a and IFNB-1b have limited benefit in relapsing-remitting and secondary progressive MS respectively. However, the benefits are achieved at extremely high cost. The evidence for IFNB-1b in relapsing-remitting MS remains inadequate due to methodological limitations of the trials and the lack of new evidence since the last DEC report in 1997.
It is difficult to judge the long-term clinical effects of interferon beta in relapsing-remitting or secondary progressive MS, since the clinical trials were of only 2-3 years duration. This is a life long disease, and there is no evidence that any of the short term benefits shown in RCTs affect long term outcomes. Another major limitation of the trials is that they do not help decision makers assess the effect of drug treatments on carers and families.
A major problem for current practice and future research is the issue of patient selection. A limited number of patients respond to these drugs but there is currently no method of selecting those who might benefit.