Subcutaneous Injection Survey: Psychometric Evaluation of a Treatment Satisfaction Instrument Associated with a Novel HIV Medication

Abstract

The 20-item Subcutaneous Injection Survey (SIS) was developed to assess patients' experience with subcutaneous self-injection of an innovative anti-HIV fusion inhibitor (T-20). It measures ease of use and impact of treatment on daily life. This study presents the results of a psychometric evaluation of the SIS. The SIS and MOS-HIV data (N = 547) from two multinational, phase III clinical trials of optimized background therapy (OBT) vs. OBT + T-20 were utilized for this evaluation. Item performance and internal consistency reliability were assessed. Exploratory factor analysis was used to identify subscales. Pearson correlations were used to examine the relationship between the SIS and the MOS-HIV scores. Patients were predominately white males. SIS items had low rates of missing data (0.9%-5.5%) and with two exceptions were not redundant, as indicated by generally moderate item-to-item correlations. Three factors were identified: daily functioning, ease of injections, and activities of daily living. The SIS also includes three individually scored items on overall injection interference with daily activities, effect of injections on daily activities, and satisfaction with personal appearance. Cronbach's alphas ranged from 0.71 to 0.87. Correlations between SIS and MOS-HIV subscales were low to moderate. The SIS is a reliable instrument for measuring patients' assessment of self-injection in HIV clinical trials. Patients' experiences with self-injection are not strongly associated with health-related quality of life.