Study: Patient-reported Methods Can Change PSSD Scores, Enhance Interpretation

Study authors looked at what constitutes meaningful within-patient score improvement for psoriasis patients.

A new analysis suggests that Psoriasis Symptoms and Signs Diary (PSSD) improvements of 15, 25, or 30 points are indicative of increasing improvements in disease burden useful to patients who have psoriasis.

Researchers writing in JAMA Dermatology looked at 666 patients with moderate to severe plaque psoriasis from the phase 3 Program to Evaluate the Efficacy and Safety of Deucravacitinib, a Selective TYK2 Inhibitor (POETYK PSO-1) clinical trial. The predefined analysis derived meaningful change thresholds by anchoring mean PSSD score change from baseline to 16 weeks to category improvements on the Patient Global Impression of Change (PGI-C) and the Patient Global Impression of Severity (PGI-S). The main study outcome was change of PSSD (anchored to PGI-C and PGI-S) from baseline to week 16.

According to the results, researchers identified three thresholds. Score improvements of at least 15 points from baseline were considered meaningful within-patient change anchored to PGI-C. Greater score improvements of 25 points were supported by PGI-C and PGI-S. Finally, a 30-point score change was able to identify patients with more significant improvements in their psoriasis symptoms and signs. 

"The patient-perceived meaningfulness of a −25-point change from baseline is supported by both the PGI-C and the PGI-S, while a −30-point meaningful within-patient change threshold identified patients who reported higher improvement on the PGI-C," the researcher concluded. "The determination of meaningful within-patient change thresholds allows for responder analyses of the PSSD score change from baseline, enhancing the patient-relevant interpretation of this widely used instrument in clinical trials of psoriasis."

The limited applicability of meaningful within-patient change thresholds for improvement to worsening symptoms or signs has not been examined and was cited as a study limitation.