Equivalence and measurement properties of an electronic version of the Psoriasis Symptom Inventory
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To evaluate the equivalence of electronic and paper versions of the Psoriasis Symptom Inventory and to examine measurement properties of the electronic version.
In a prospective, randomized, crossover, non-interventional study in adult subjects (age ≥18 years) with plaque psoriasis conducted over a period of 15 days, subjects were randomized to two groups, completing either the paper or electronic Psoriasis Symptom Inventory daily for 7 consecutive days followed by the alternate version. Equivalence was assessed by the intraclass correlation coefficient (ICC) between both administration modes. Differences in scores were also tested using paired Student’s t test. Measurement properties included internal consistency reliability, test–retest reliability, and convergent and discriminant validity between the Psoriasis Symptom Inventory and (1) disease-specific (Dermatology Life Quality Index) and (2) general health (SF-36v2) status.
Eighty subjects [74 % (59/80) moderate-to-severe psoriasis; 26 % (21/80) mild psoriasis receiving systemic treatment] were enrolled from 8 sites in the USA. The two modes were highly concordant for both total (ICC = 0.97) and individual item scores (ICC range = 0.93–0.97). Response bias testing showed no differences based on completion order with all ICC values >0.91. All mean score differences, except for one item (“flaking”), were non-significant (P > 0.05). Minimum values for reliability (>0.70) and validity (convergent, r ≥ 0.40) were exceeded for the electronic Psoriasis Symptom Inventory.
Equivalence between paper and electronic versions of the Psoriasis Symptom Inventory and strong measurement properties of the electronic mode indicated a successful migration from paper to electronic format of the Psoriasis Symptom Inventory.
KeywordsPlaque psoriasis Patient-reported outcome Symptom Psychometric properties Equivalence
The authors wish to thank Jon Nilsen, PhD (Amgen Inc.) for providing writing support.
Conflict of interest
This study was funded by Amgen Inc. DMB, MLM, MS, and TCC are employees of Health Research Associates, Inc., which received funding for this study. DC and HV are employees and shareholders of Amgen Inc.
- 2.Martin, M. L., McCarrier, K., Bushnell, D. M., Gordon, K., Chiou, C.-F., Huang, X., Ortmeier, B., & Kricorian, G. (2011). Validation of the Psoriasis Symptom Inventory (PSI), a patient reported outcome measure. In 20th European academy of dermatology and venereology congress. Lisbon, Portugal.Google Scholar
- 3.Martin, M. L., McCarrier, K., Bushnell, D. M., Gordon, K., Chiou, C.-F., Huang, X., et al. (2012). Validation of the Psoriasis Symptom Inventory (PSI), a patient-reported outcome measure. Journal of the American Academy of Dermatology, 66(4, Supplement 1), AB207.Google Scholar
- 4.Lui, H., & Mamelak, A. (2009). Plaque psoriasis. Updated: Sep 30, 2009. http://www.emedicine.com/derm/topic365.htm#section~clinical (see causes).
- 5.Wilke, R., Burke, L., & Erickson, P. (2004). Measuring treatment impact: A review of patient reported outcomes and other efficacy endpoints in approved product labels. Controlled Clinical Trials, 26, 636–662.Google Scholar
- 8.F. a. D. A. (FDA). (2009). Guidance for industry. Patient-reported outcome measures: Use in medical product development to support labeling claims. Retrieved December, 2009, 2009.Google Scholar
- 9.Coons, S. J., Gwaltney, C. J., Hays, R. D., Lundy, J. J., Sloan, J. A., Revicki, D. A., et al. (2009). Recommendations on evidence needed to support measurement equivalence between electronic and paper-based patient-reported outcome (PRO) measures: ISPOR ePRO good research practices task force report. Value Health, 12(4), 419–429.PubMedCrossRefGoogle Scholar
- 10.Martin, M., Chen, T., Chau, D., & Viswanathan, H. (2012). Qualitative interviews with psoriasis patients evaluating paper to electronic migration of the Psoriasis Symptom Inventory (PSI). In Paper presented at the ISOQOL 2012. Budapest, Hungary.Google Scholar
- 11.Martin, M., McCarrier, K., Chiou, C., Gordon, K., Kimball, A., Van Voorhees, A., Gottlieb, A., Huang, X., Globe, D., Chau, D., Viswanathan, H., & Kricorian, G. (2013). Early development and qualitative evidence of content validity for the Psoriasis Symptom Inventory (PSI), a patient-reported outcome measure of psoriasis symptom severity. Journal of Dermatological Treatment, 24(4), 255–260.Google Scholar
- 12.Bushnell, D. M., Martin, M. L., McCarrier, K., Gordon, K., Chiou, C. F., Huang, X., Ortmeier, B., & Kricorian, G. (2013). Validation of the Psoriasis Symptom Inventory (PSI), a patient-reported outcome measure to assess psoriasis symptom severity. Journal of Dermatological Treatment, 24(5), 356–360.Google Scholar
- 13.Revicki, D. A., Jin, Y., Chau, D., & Viswanathan, H. (2012). Reliability and validity of the Psoriasis Symptom Inventory in Patients with moderate to severe psoriasis. In International society for quality of life research 19th annual conference. Budapest.Google Scholar
- 14.Revicki, D. A., Jin, Y., Wilson, H. D., Chau, D., & Viswanathan, H. N. (2013). Reliability and validity of the psoriasis symptom inventory in patients with moderate-to-severe psoriasis. Journal of Dermatological Treatment. doi: 10.3109/09546634.2013.769042.
- 18.Nunnally, J., & Bernstein, I. (1994). Psychometric theory (3rd ed.). New York: McGraw-Hill.Google Scholar
- 19.Cohen, J. (1988). Statistical power analysis in the behavioral sciences (2nd ed.). Hillsdale, NJ: Lawrence Erlbaum Associates, Inc.Google Scholar
- 20.Bushnell, D. M., Reilly, M. C., Galani, C., Martin, M. L., Ricci, J. F., Patrick, D. L., et al. (2006). Validation of electronic data capture of the irritable bowel syndrome–quality of life measure, the work productivity and activity impairment questionnaire for irritable bowel syndrome and the EuroQol. Value Health, 9(2), 98–105.PubMedCrossRefGoogle Scholar