Background There is increasing evidence that stressors contribute to the severity of chronic inflammatory diseases such as psoriasis. However, much less is known about possible individual differences between patients in their stress reactivity, particularly the role of cognitive and behavioural factors, such as the role of worrying or scratching behaviour, in reaction to itch.
Objectives To investigate the direct and moderating role of individual stress reactivity factors, particularly of cognitive and behavioural patterns of worrying and scratching, on the relationship between daily stressors and changes in disease severity [Psoriasis Area and Severity Index (PASI)] and itch in patients with psoriasis.
Methods Patients were followed for 6 months through monthly clinical and self-reported measures of daily stressors, itch, disease severity and individual reactivity factors. Data from 62 patients were suitable for analysis.
Results Cognitive and behavioural patterns of worrying and scratching were both independently related to an increase 4 weeks later in disease severity (PASI) and itch, at moments when patients experienced a high level of daily stressors. At these moments, stressors also interacted with vulnerability factors, showing that patients with more daily stress and high worrying and scratching had particularly worsened disease severity and itch.
Conclusions Patients with high levels of worrying and scratching are most vulnerable to the impact of stressors on their psoriasis, particularly at highly stressful periods.