Correlation between Dermatology Life Quality Index (DLQI) scores and Work Limitations Questionnaire (WLQ) allows the calculation of percent work productivity loss in patients with psoriasis.

Abstract

Data on indirect costs are vital for cost-effectiveness studies from a societal perspective. In contrast to quality of life, information on productivity loss is rarely collected in psoriasis trials. We aimed to identify a model to deduce indirect costs (presenteeism and absenteeism) of psoriasis from the Dermatologic Life Quality Index (DLQI) of affected patients to facilitate health economic evaluations for psoriasis. We undertook a cross-sectional mapping study including 201 patients with physician-diagnosed psoriasis and investigated the relationship between quality of life (DLQI) and productivity loss (Work Limitations Questionnaire, WLQ--using the "output demands" subscale) using linear bootstrap regression analysis to set up an equation model allowing the calculation of percent work productivity loss per DLQI unit increase. DLQI and WLQ scores were significantly correlated (r = 0.47; p < 0.0001) The final equation model suggests a 0.545 and 0.560% decrease in productivity due to presenteeism and absenteeism per DLQI unit increase, with y-intercepts at 1.654 and 0.536, respectively. In the absence of data on indirect cost, work productivity loss due to psoriasis can be estimated from DLQI scores using the equations, Y = 0.545 × DLQI score + 1.654 for presenteeism (%) and Y = 0.560 × DLQI score + 0.536 for absenteeism (%).