Psychometric Properties of an Instrument for Assessing Treatment Satisfaction Associated With Pramlintide Use

Abstract

Background The clinical benefits of any new treatment depend substantially on patient acceptance and treatment satisfaction, because only well-accepted treatments will be widely used. Thus, it is important to understand how patients experience a new treatment. Objective This study assessed the psychometric properties of a questionnaire (PRAM-TSQ) designed to measure treatment satisfaction in patients using pramlintide (an analog of amylin, a glucoregulatory hormone co-secreted with insulin), which is designed to improve glucose control. Methods Patients with diabetes completed the 14-item PRAM-TSQ at the end of 2 separate placebo-controlled, double-blind, randomized clinical trials in which they added active or placebo pramlintide to their established insulin regimen. Factor analysis was used to assess item clustering for the PRAM-TSQ, and the Cronbach's α measure of inter-item agreement was used to assess scale reliability. PRAM-TSQ validity was assessed by comparing scores between treatment arms, and effect sizes were measured by the η statistic. Validity was also assessed by associations (Pearson correlations) between the PRAM-TSQ and clinical study outcomes (end of study values and during study changes in clinical measures: postprandial glucose [PPG], A1C, weight, and insulin requirements). Results Scaling revealed 4 PRAM-TSQ components: Global Benefits, Specific Benefits, Absence of Side Effects, Treatment Preference. The total composite PRAM-TSQ had good reliability in both studies (type 1 α = .93; type 2 α = .94); subscale reliabilities ranged from .65 to 94. Composite scores differed for pramlintide-treated and placebo-treated patients (type 1 P < .01; type 2 P < .05), and were associated with lower PPG, weight, and insulin requirements (all P < .05). Results were similar for PRAM-TSQ subscales assessing Global Benefits and Treatment Preference; Specific Benefits subscale scores were associated with lower PPG and weight (all P < .05). Conclusions The PRAM-TSQ shows evidence of being a valid, reliable instrument for assessing treatment satisfaction in patients using pramlintide. The subscales are comprehensive and sensitive to the known potential effects of pramlintide treatment. Diabetes educators can use patient responses to the PRAM-TSQ to facilitate treatment adherence by reminding patients of treatment benefits they experience and by helping patients overcome negative effects they report.