Chronic inflammatory skin conditions significantly impact the quality of life (QoL) of those affected. Itch is a cardinal symptom in many of these conditions, contributing decisively to the burden of disease. This cross-sectional study explored how itch and related factors mediate the relationship between disease severity and QoL impairment. Adult patients with chronic pruritus arising from psoriasis, atopic dermatitis, chronic prurigo, or chronic urticaria completed a set of validated questionnaires assessing worst and average itch intensity (worst itch intensity on the numerical rating scale WI-NRS/average itch intensity on the numerical rating scale AI-NRS), impairment of QoL with the 5-pruritus life quality (5PLQ), daily time with itch, scratching frequency, and sleep disturbance. Disease severity was evaluated using validated disease-specific scales. Spearman’s rank correlation was performed to assess intercorrelations between 5PLQ scores, disease severity, and itch-related factors. A linear regression analysis investigated associations of 5PLQ with demographic and clinical factors. Mediation analyses examined whether the link between disease severity and 5PLQ scores was mediated by itch intensity, daily itch duration, scratching frequency, and sleep disturbance. A total of 522 patients (282 female, median age: 56.0 years) participated in the study. 5PLQ scores correlated weakly with disease severity (r = 0.201, p < 0.001), and strongly with itch-related factors (r = 515–0.603, p < 0.001). The linear regression analysis revealed a positive association between 5PLQ scores and female sex (β: 0.887, p = 0.003), moderate disease severity (β: 1.552, p = 0.032), scratching frequency (β: 0.370, p < 0.001), and sleep disturbance (β: 0.427, p < 0.001). Mediation analyses showed that the association between disease severity and QoL impairment was partially mediated by average itch intensity (indirect β: 0.168, p = 0.049), daily itch duration (indirect β: 0.270, p < 0.001), scratching frequency (indirect β: 0.205, p = 0.010), and sleep disturbance (indirect β: 0.235, p = 0.006). Average itch intensity, daily itch duration, scratching, and sleep disturbance mediate the relationship between disease severity and impairment of QoL. Interventions targeting these aspects of disease may improve patient outcomes. Chronic inflammatory skin conditions are highly prevalent in our society, contributing to substantial impairment of quality of life. Itch is the major symptom associated with these diseases, impacting the daily activities and sleep of those affected. We enrolled 522 patients with chronic itch arising from common inflammatory skin condition (atopic dermatitis, psoriasis, prurigo, or urticaria) at two clinics and ten dermatological offices across the states of North Rhine-Westphalia and Lower Saxony in Germany to study how itch-related factors explain the known relationship between disease severity and impairment of quality of life. Patients completed a set of questionnaires inquiring about various aspects of itch (including intensity, daily time with itch, scratching frequency, sleep disturbance), as well as impairment of quality of life. A dermatologist assessed disease severity on the basis of the skin examination. We observed significant associations between disease severity, itch-related factors, and impairment of quality of life. The amount of time patients experienced itch in a day was the factor that most strongly explained how disease severity led to an impaired quality of life. The degree of sleep disturbance was the next most important factor, followed by how often patients scratched and average itch intensity but not peak itch episodes. These results highlight that different aspects of itch play a role in reducing quality of life in patients with inflammatory skin diseases. It is therefore of great importance to assess these factors in routine care. Treatments that target these dimensions of itch may improve care and well-being in this patient population.
Pereira et al. (Tue,) studied this question.