An assessment of the different tools used to assess treatments in pyoderma gangrenosum

Pyoderma gangrenosum (PG) is a rare, inflammatory skin disease that results in painful sores and is difficult to heal. In the U.K., PG occurs in 3‐10 people per million every year. Due to its rarity, there is a lack of validated tools (meaning methods, and also called ‘instruments’, that have been validated, to show they are effective) for assessing the effectiveness of treatments, resulting in the absence of a uniform standard of care. In this study from Canada and the U.S.A., we aimed to identify, through a systematic process, all the current tools used in measuring outcomes in PG within clinical trials in the scientific literature. We also evaluated the validation surrounding these instruments using guidelines and checklists from international initiatives such as COSMIN (COnsensus‐based Standards for the selection of health status Measurement INstruments). In total, we found seven clinical trials that utilized 20 different instruments. Of these, 17 of the instruments lacked any validation data. The remaining three validated instruments were speed of healing, physician global assessment, and resolution of inflammation. However, these three instruments lacked validation for half of the COSMIN requirements. We hope that the identification of these 20 different instruments for PG can help inform the scientific and medical community; however, currently, we cannot recommend any of these instruments. We conclude that more validation studies are required for existing instruments, and new instruments may need to be developed to help create a consensus on measuring outcomes for PG. Once there is a consensus, treatments for PG can be compared to each other using the same instruments, to identify novel therapies for this debilitating disease. Linked Article: Lu et al. Br J Dermatol 2020; 183: 821–828.