Development and psychometric evaluation of the self-assessment of psoriasis symptoms (SAPS) - clinical trial and the SAPS - real world patient-reported outcomes.
OBJECTIVE
The Self-Assessment of Psoriasis Symptoms - Clinical Trials (SAPS-CT) and SAPS - Real World (SAPS-RW) were simultaneously created to assess the experience of plaque psoriasis in two unique contexts.


METHODS
Qualitative and quantitative research was conducted in four phases namely concept elicitation, questionnaire construction, content evaluation and psychometric evaluation.


RESULTS
Following concept elicitation, 18 concepts were selected to inform questionnaire construction of the SAPS-CT and SAPS-RW. To accommodate each context of use, the SAPS-CT asks respondents to rate the target symptom 'at its worst' in the 24 h prior to assessment, while the SAPS-RW asks respondents to rate the target symptom "on average" in the 7 days prior to assessment. Cognitive debriefing confirmed that patients could comprehend and provide meaningful responses to both versions and, after minor modifications, resulted in 11-item questionnaires administered in an observational study (N = 200). Results from the observational study informed further item reduction (SAPS-RW to six items and SAPS-CT to nine items) and demonstrated that scores from each were reliable (Cronbach's α > 0.90, test-retest intraclass correlation coefficient >0.70), construct valid and able to differentiate among clinically distinct groups.


CONCLUSIONS
The SAPS-CT and SAPS-RW are content-valid PRO questionnaires capable of producing psychometrically sound scores when administered chronic to plaque psoriasis patients.
a Keck School of Medicine , University of Southern California , Los Angeles , CA , USA.
April W
AW
Armstrong
b Adelphi Values USA, Patient-Centered Outcomes , Boston , MA , USA.
Benjamin
B
Banderas
b Adelphi Values USA, Patient-Centered Outcomes , Boston , MA , USA.
Catherine
C
Foley
b Adelphi Values USA, Patient-Centered Outcomes , Boston , MA , USA.
Jonathan
J
Stokes
c AbbVie, Health Economics and Outcomes Research , North Chicago , IL , USA.
Murali
M
Sundaram
b Adelphi Values USA, Patient-Centered Outcomes , Boston , MA , USA.
Alan L
AL
Shields
D000328:Adult; D000368:Aged; D002986:Clinical Trials as Topic; D003879:Dermatologic Agents / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D000071066:Patient Reported Outcome Measures; D011565:Psoriasis / Q000188:drug therapy / Q000523:psychology*; D011594:Psychometrics; D011788:Quality of Life; D012647:Self-Assessment; D011795:Surveys and Questionnaires; D055815:Young Adult
D003879:Dermatologic Agents
PRO; chronic plaque psoriasis; context of use; instrument; psychometric; qualitative