A Cochrane review included 2 studies with a total of 1 300 subjects treated with subcutaneous injections of recombinant human ciliary neurotrophic factor. The methodological quality of these trials was considered adequate. No significant difference was observed between ciliary neurotrophic factor and placebo groups for survival, the primary outcome measure. The relative risk was 1.07 (95% CI 0.81 to 1.41). No significant differences between the groups were observed for most of the secondary outcomes. However, a significant increase of the incidence of several adverse events was noted in groups treated with higher doses of CNTF.
Comment: The quality of evidence is downgraded by imprecise results (limited study size for each comparison).