Supplementary Figure S2. Factors linked to percent scalp regrowth (model estimates).

This figure shows results from our adjusted regression model, which predicts how much hair
regrowth patients achieved during each course of JAK inhibitor therapy. The model adjusts for
factors including drug type, treatment duration, order of medication use (line of therapy),
switcher status, sex, race, age, alopecia subtype, and baseline hair regrowth. Each row represents
one factor and its estimated effect on scalp regrowth, shown as a horizontal bar for the 95%
confidence interval, while holding all other factors constant. Rows positioned to the right of zero indicate more expected regrowth than the reference, and those to the left indicate less. Later
treatment lines refer to patients who used a JAK inhibitor after one or more prior switches (e.g.,
third-line after two previous JAKs), and these later lines were generally linked to less regrowth
than first-line use. Longer treatment duration was associated with early improvement (Duration
spline 1) that plateaued (Duration spline 2) over time. Positive values indicate greater regrowth,
and negative values indicate less regrowth relative to the reference. Statistical significance is
marked by asterisks: p < 0.05 (*), p < 0.01 (**), a factor is not statistically significant when its
95% confidence interval crosses zero.