Predictors of malignancy development in patients with chronic pruritus

Background: Patients with pruritus have been shown to have an increased incidence of certain subtypes of malignancy. Objective: To assess predictors of malignancy in patients with chronic pruritus without prior dermatologic diagnoses. Methods: Case-control study of 398 patients with chronic pruritus who developed a malignancy were compared with 8346 patients with chronic pruritus who did not develop a malignancy. Primary outcomes were odds of developing incident malignancy. Results: Age greater than 60 years (OR 4.04, 95% CI 3.08, 5.31), male sex (OR 1.39, 95% CI 1.13, 1.71) and liver disease (OR 2.37, 95% CI 1.00, 5.65) were predictors of malignancy development in patients with chronic pruritus and non-diseased skin. In an exploratory analysis with multiple imputation via chained equations, age greater than 60 years (OR 4.13, 95% CI 3.15, 5.42), male sex (OR 1.26, 95% CI 1.02, 1.55), and current or prior smoking (OR 2.02, 95% CI 1.42, 2.88) were predictors of malignancy development in patients with chronic pruritus and non-diseased skin. Limitations: Potential for misclassification and detection biases. Missing data. Conclusions and relevance: In patients with chronic pruritus without concomitant dermatologic diagnoses, older age, male sex, liver disease and tobacco abuse increase the odds of an underlying malignancy.