Development and reliability testing of a standardized questionnaire to assess psoriasis phenotype

Abstract

Background: Psoriasis genetics researchers have utilized separate and widely differing survey instruments to capture clinical data to be utilized in genotype-phenotype studies, which make comparison and collaboration studies among these researchers difficult.

Objective: The purpose of this study was to develop and validate a clinical survey instrument to facilitate future collaborative genotype-phenotype studies among psoriasis genetics researchers.

Methods: The Delphi method was employed to obtain international consensus on components of the novel survey instrument. The survey was pretested for acceptability purposes, and then formally tested for reliability using 3 independent raters interviewing 48 subjects with psoriasis.

Results: Data showed high or moderately high agreement for questions relating to place of birth (85% to 100% in agreement), family origin (kappa = 0.48 -1.0), psoriasis history (kappa = 0.66-1.0), patient medical history (kappa = 0.76-1.0), distribution of lesions (kappa = 0.73-1.0), precipitating factors (kappa = 0.79-1.0), joint involvement (kappa = 0.74-.91), and treatment history, including use of oral retinoids, methotrexate, and etanercept (kappa = 0.73-1.0). Other parameters had lower degrees of agreement.

Limitations: The time involved and the need for the rater to be a clinician with knowledge of psoriasis may preclude widespread use of this survey instrument.

Conclusion: We developed a novel, reliable survey instrument that can be used to gather clinical information in a standardized manner from psoriasis patients participating in clinical and genetics research studies.