The number of the treatment emergent adverse events, serious adverse events and adverse events leading to discontinuation among patients with moderate-to-severe disease treated with abrocitinib regardless of discontinuation from study treatment.

An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly; was a suspected transmission via a Pfizer product of an infectious agent, pathogenic or non-pathogenic or other situations where medical or scientific judgement should be exercised by investigator. AEs included SAEs and all non-SAEs.

The severity of itch (pruritus) due to atopic dermatitis (AD) was assessed using the PP-NRS, a validated horizontal NRS. Participants were asked to assess their worst itching due to AD over the past 24 hours on an NRS with scale ranging from 0 to 10, where 0= no itch and 10= worst itch imaginable. Higher scores indicated worse itch.

EASI quantifies severity of AD based on severity of lesion clinical signs and percentage (%) of body surface area (BSA) affected. Severity of clinical signs of AD lesions (erythema, induration/papulation, excoriation and lichenification) were scored separately for each of 4 body regions (head and neck, upper limbs, trunk \[including axillae and groin)\] and lower limbs \[including buttocks\]) on a 4-point scale: 0= absent; 1= mild; 2= moderate; 3= severe. EASI area score was based on % BSA with AD in body region: 0 (0%), 1 (\>0 to \<10%), 2 (10 to \<30%), 3 (30 to \<50%), 4 (50 to \<70%), 5 (70 to \<90%) and 6 (90 to 100%). Total EASI score =0.1\*Ah\*(Eh+Ih+Exh+Lh) + 0.2\*Au\*(Eu+Iu+ExU+Lu) + 0.3\*At\*(Et+It+Ext+Lt) + 0.4\*Al\*(El+Il+Exl+Ll); A = EASI area score; E = erythema; I = induration/papulation; Ex = excoriation; L = lichenification; h = head and neck; u = upper limbs; t = trunk; l = lower limbs. Total EASI score ranged from 0.0 to 72.0, with higher scores indicating greater severity of AD.