Examining the association between pruritus and quality of life in patients with atopic dermatitis treated with crisaborole.

BACKGROUND: Pruritus is a leading cause of reduced health-related quality of life (QoL) in atopic dermatitis (AD). Crisaborole ointment is a non-steroidal phosphodiesterase 4 inhibitor for the treatment of mild-to-moderate AD. In identical Phase 3 studies (NCT02118766, NCT02118792), crisaborole reduced disease and pruritus severity versus vehicle. OBJECTIVE: Quantify the relationship between pruritus and QoL using data from these studies. METHODS: Patients aged ≥2 years were randomly assigned 2 : 1 to receive crisaborole:vehicle twice daily for 28 days. QoL was measured at baseline and day 29 using the Dermatology Life Quality Index (DLQI; patients aged ≥16 years), the Children's Dermatology Life Quality Index (CDLQI; patients aged 2-15 years) and the Dermatitis Family Impact (DFI; caregivers of patients aged 2-17 years). Pruritus was measured using the Severity of Pruritus Scale (SPS), a 4-point scale from 0 ('no itching') to 3 ('bothersome itching/scratching that disturbs sleep'), and captured morning and evening via electronic diary. Data from crisaborole and vehicle arms were pooled for this analysis. A repeated-measures longitudinal model was used to estimate relationships between pruritus (SPS) and QoL (DLQI, CDLQI and DFI in separate analyses). RESULTS: One thousand five hundred and twenty two patients received crisaborole or vehicle. A linearity assumption for the relationship between SPS and DLQI (n = 294), CDLQI (n = 1200), and DFI (n = 1293) was appropriate. For DLQI, SPS score of 0 was associated with 'no negative effect on patient QoL'; SPS score of 1 was associated with 'small effect on patient QoL'; SPS score of 2 was associated with 'moderate effect on patient QoL'; and SPS score of 3 was associated with 'very large effect on patient QoL'. The pattern of relationships between SPS and CDLQI and DFI was similar. CONCLUSIONS: The relationships between SPS and DLQI, CDLQI and DFI substantiate the significant link between pruritus and patient/caregiver QoL in AD.