Heal House vitiligo research 70 · Original article
From what percentage does vitiligo treatment become 'meaningfully' better?
Psychometric Properties and Meaningful Change Thresholds of the Vitiligo Area Scoring Index
In short
The effect of vitiligo treatment is evaluated using the Vitiligo Area Scoring Index (VASI), which measures the extent of white patches. We confirmed that when this score improves by about 30% for the whole body and 50% for the face, patients actually feel that they have 'improved.'
Clinical trial results show numbers like 'improved by X%.' However, the criterion for 'whether that degree of improvement is perceived by the patient' has not been clear. When the criterion is unclear, it is difficult to determine whether a new treatment is truly meaningful. Therefore, we analyzed phase 2 clinical trial data of an oral new drug (upadacitinib) together with patient interviews. We sought to find the boundary for a 'meaningful improvement' in the VASI. I participated in this study as a co-investigator.
Q1 What data were used and how was it analyzed?
We analyzed phase 2 clinical trial data of an oral new drug (upadacitinib) together with stories heard directly from patients. This clinical trial was conducted at 35 institutions in Canada, France, Japan, and the United States. Participants used the new drug at various doses or a placebo for 24 weeks. The analysis included data from 164 individuals (mean age 46 years, 103 women [63%]) and interviews with 14 individuals. First, we confirmed how reliable the VASI is. When measured twice during a stable period, the values were nearly identical. This means it is a tool that can measure consistently without fluctuation.
Q2 What percentage was the threshold for “meaningful improvement”?
The point at which patients actually felt improvement was around a 30% improvement in total body score and a 50% improvement in facial score. Interestingly, these values are lower than the thresholds commonly used in past clinical trials (50% for total body, 75% for face), suggesting that the older criteria were somewhat strict. Patients perceive a meaningful change even with less improvement than those older benchmarks. However, the face is a visible area, so it required more improvement than the rest of the body for patients to notice a difference. The table below summarizes the thresholds by body area.
Thresholds for a 'meaningful improvement' as perceived by patients
| Area | Meaningful improvement threshold | In simple terms |
|---|---|---|
| Whole body | Improvement of 30% or more | Perceived when about 30% of body color returns |
| Face | Improvement of 50% or more | Perceived only when about half of facial color returns |
Q3 Why does this threshold matter?
Because it connects the number 'improved by X%' to the patient's actual feeling. When the threshold is clear, we can more accurately determine whether a new treatment produces a truly meaningful effect. It also helps standardize the criteria for success, which have varied across clinical trials. Most importantly, this threshold comes from the patient's voice, not the doctor's eye. Thanks to this, future evaluations of vitiligo treatment will be closer to the changes that patients actually feel.
Closing remarks
We can now determine whether vitiligo treatment is successful based on the changes that patients actually feel. This study has drawn that 'boundary of perception' in numbers. In an era when new treatments are emerging, it will serve as a fair yardstick to measure their effects from the patient's perspective.
