From inhibition of radiographic progression to maintaining structural integrity: a methodological framework for radiographic progression in rheumatoid arthritis and psoriatic arthritis clinical trials.

Usually, a clinical trial in rheumatoid arthritis and psoriatic arthritis aiming to demonstrate that a new antirheumatic drug treatment can inhibit progression of structural damage has a 'superiority design': The new treatment is compared to placebo or to another active treatment. Currently, many new drug treatments have shown to be able to completely suppress progression (progression rates close to zero). For largely unknown reasons, during the last 10 years, radiographic progression rates in clinical trials have gradually decreased, so that progression rates in the comparator groups are often too low to demonstrate meaningful inhibition, and thus superiority of the new treatment. We here propose an alternative framework to demonstrate that new treatments have the ability to 'preserve structural integrity' rather than to 'inhibit radiographic progression'. Anno 2013, preserving structural integrity is conceptually more realistic than inhibiting radiographic progression.