What do the terms “double-blind” and “placebo-controlled” study mean?

Most clinical trials are conducted as placebo-controlled studies. A “randomizer” assigns participating patients to different groups: one group receives a dummy drug (placebo), while another group is treated with the study drug. The two are indistinguishable to the naked eye. Neither the patient nor the study center knows which patient is receiving the placebo or the test drug (“double-blind study”).

Only after the study is completed does the study’s central organization disclose the patients’ group assignments, and the efficacy in both groups is compared. The placebo-controlled, double-blind study design is intended to ensure that study results are determined objectively and are not subject to the understandable wishful thinking of patients and physicians. For individual patients, clinical trials (Phases 2 and 3) involve a treatment duration of 6–18 months, depending on the trial.

The total duration of a study, from its start to the announcement of the results, is usually 2–3 years. This time is required due to the extensive regulatory preparations in the participating countries, the staggered implementation of the study at the individual ALS centers, and the complex statistical analysis of large studies.