DEVELOPMENT OF A PATIENT-REPORTED OUTCOME MEASURING PATIENTS’ EXPERIENCE WITH IMMUNOGLOBULIN TREATMENT

Abstract

Introduction The objective of this study is to assess the impact of immunoglobulin replacement therapy (IgRT) in individuals with primary immunodeficiency diseases (PIDD) and to develop a self-reported measure evaluating patients’ experiences with IgRT, the Immunoglobulin Patient Experience with Treatment (IgPET), applicable to both subcutaneous (SC) and intravenous (IV) routes of administration (ROA) and different sites of care. Methods Cognitive interviews (CIs) were conducted with patients with PIDD in the US to better understand their experiences with and impact of IgRT and to obtain feedback on draft IgPET items. IgPET concepts were identified via literature searches for concepts applicable to all PIDD patients using IgRT. Questionnaire items were tested and refined through 3 iterative sets of CIs. Results CIs were conducted with 21 participants (females=19 [90%]; mean age [range], 42.5 [17–70] years; mean [range] years since PIDD diagnosis, 8.3 [1–26]). Approximately half of the patients were treated by each RoA. Overall, patients were generally “satisfied” with their current IgRT. The most commonly reported negative impacts of IgRT were side effects following IgRT (n=11 [52%]) and impact on social/family activities (n=6 [29%]). Impacts were generally similar across subgroups regardless of ROA or site of care. 29 items were tested in round 1, 20 in rounds 2 and 3. The final 19-item IgPET was easy to understand and answer, and important to patients’ IgRT experiences. Conclusions The IgPET is a new measure assessing patients’ experiences with IgRT. It was subsequently validated in 814 IgRT patients via a cross-sectional, observational study.