Prurigo Control Test shows potential for disease evaluation in clinical practice, trials

Key takeaways:

• While other evaluation tools do not address disease control, the Prurigo Control Test (PCT) does.
• In a validation study, the PCT demonstrated good internal consistency, reliability and reproducibility.

Researchers have developed and validated a new tool for evaluating disease control among patients with chronic prurigo, according to a study.

Controlling chronic prurigo (CPG), a disease characterized by chronic itching, is the ultimate goal during treatment. And while there are many methods for assessing CPG activity, including IGA and the Prurigo Activity and Severity Score, these tools do not address disease control.

To fulfill this unmet need, Martin Metz, MD, of the Institute of Allergology, Charité-Universitätsmedizin Berlin, and colleagues developed a measurement tool called the Prurigo Control Test (PCT) that focuses on helping patients control their disease. They then tested the tool in a validation study comprised of 95 patients.

“The development process aimed to generate a straightforward, short [patient-reported outcome measure (PROM)] that is easy to administer, complete and evaluate,” Metz and colleagues wrote.

The PCT consisted of five questions that patients answered based on a 2-week recall period. The questions included:

• “Overall, how severe were your skin lesions in the past 2 weeks?
• How often did you have to scratch yourself because of your skin disease in the last 2 weeks?
• How often has your skin disease prevented you from sleeping normally in the last 2 weeks?
• How much was your quality of life impaired by your skin disease in the last 2 weeks?
• How well has your therapy been able to control your skin disease in the last 2 weeks?”

A cutoff value of 10 points was assigned to identify which patients were experiencing poor vs. well-controlled CPG, with a score lower than 10 points indicating poorly controlled disease and a score 10 or greater indicating well-controlled disease.

Results showed that the test yielded good internal consistency and reliability with a Cronbach alpha coefficient value of 0.86. The authors also reported that the PCT was successful at distinguishing between patients who differed in prurigo control.

To assess the test-retest reliability, all patients completed the test twice within a 2-week interval along with a global self-rating of their current prurigo control status. Following this second round of testing, the PCT received an intraclass correlation coefficient of 0.94, which signifies excellent reproducibility.

“Results of this qualitative study show that the PCT is, to our knowledge, the first tool to assess disease control in patients with CPG,” the authors concluded. “Its retrospective approach, brevity and simple scoring likely make the PCT suitable for clinical practice and trials.”