Research Techniques Made Simple: Validation of Outcome Measures in Dermatology Kate V. Viola, MD, MHS 1 Tamar Nijsten, MD, PhD 2 Karthik Krishnamurthy, DO 1 1.Albert Einstein College of Medicine, New York, USA 2. Erasmus Medical Center, Rotterdam, The Netherlands.

Outcome Measures Quantify: Clinical disease severity: -Generalized health: BSA, PGA -Disease specific: PASI, SCORAD Patient-reported outcomes: -Generic: SF36 -Dermatology: DLQI, Skindex

Development of Outcome Measures Item Generation – Exploratory interviews – Systematic literature reviews – Consultation with disease experts Item Reduction – Target audience administration – Impact factor for question inclusion and exclusion

Property Testing: Validity Content validity - instrument adequacy in addressing all relevant items Convergent validity - studied tools correlate with tools measuring same underlying construct Construct validity - different groups of patients show score difference

Item Structure for Skin Disease Outcome Measure

Property Testing: Reliability Test – retest reliability- score consistency when administered at different times (interclass correlation coefficients) Internal consistency- degree to which set of items measures the same construct (Cronbach’s alpha test)

Property Testing : Responsiveness and Response Distribution Responsiveness- instrument’s ability to change when patient experiences change in disease state (minimal clinical important difference) Response distribution- assesses whether entire range of item scores is utilized (measurement indicators)

Outcome Measures: Role in Dermatology Supplements clinical judgment to optimize management approach and treatment Provides insight into educational gaps and psychosocial issues Influences clinical guideline recommendations Plays a role in future cost-effective treatment strategies