Five-year malignancy incidence in patients with chronic pruritus: a population-based cohort study aimed at limiting unnecessary screening practices.
BACKGROUND
The incidence of malignancy in patients with chronic pruritus and nondiseased skin is unknown.


OBJECTIVE
We sought to assess the hazard ratio (HR) of incident overall malignancy and incident malignancy by subtype in patients with chronic pruritus during the 5 years after diagnosis.


METHODS
A population-based cohort study was performed in the Health Improvement Network. In all, 8744 patients with chronic pruritus were matched with 31,580 patients without chronic pruritus based on sex, age, and practice. Primary outcomes were HR of incident malignancy and HR of malignancy subtypes.


RESULTS
The fully adjusted HR for incident malignancy in patients with chronic pruritus was 1.14 (95% confidence interval 0.98-1.33). The fully adjusted HR for incident hematologic malignancy and incident bile duct malignancy in patients with chronic pruritus was 2.02 (95% confidence interval 1.48-2.75) and 3.73 (95% confidence interval 1.55-8.97), respectively. The incidence of hematologic malignancy and cholangiocarcinoma in patients with chronic pruritus was 0.0016 and 0.0003 per person-year, respectively.


CONCLUSIONS
Potential for misclassification and detection biases is a limitation.


CONCLUSIONS
Chronic pruritus without concomitant skin changes is a risk factor for having undiagnosed hematologic and bile duct malignancies, but not other malignancies. The overall incidence of these malignancies in patients with chronic pruritus is very low.
Philadelphia Department of Veterans Affairs Medical Center, Philadelphia, Pennsylvania; Department of Dermatology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania. Electronic address: fett@ohsu.edu.
Nicole
N
Fett
Department of Biostatistics and Epidemiology, Center for Clinical Epidemiology and Biostatistics, Center for Pharmacoepidermiology Research and Training, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
Kevin
K
Haynes
Department of Biostatistics and Epidemiology, Center for Clinical Epidemiology and Biostatistics, Center for Pharmacoepidermiology Research and Training, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
Kathleen Joy
KJ
Propert
Department of Dermatology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania.
David J
DJ
Margolis
D000328:Adult; D017677:Age Distribution; D000368:Aged; D001650:Bile Duct Neoplasms / Q000453:epidemiology* / Q000473:pathology; D016022:Case-Control Studies; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D002908:Chronic Disease; D015331:Cohort Studies; D016001:Confidence Intervals; D055088:Early Detection of Cancer / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D019337:Hematologic Neoplasms / Q000453:epidemiology* / Q000473:pathology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010257:Paraneoplastic Syndromes / Q000453:epidemiology* / Q000473:pathology; D016016:Proportional Hazards Models; D011537:Pruritus / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology*; D018570:Risk Assessment; D017678:Sex Distribution; D016019:Survival Analysis; D013997:Time Factors; D019564:Unnecessary Procedures; D055815:Young Adult
chronic pruritus; generalized pruritus; itch; paraneoplastic signs; pruritus; skin signs of systemic disease