DiBenedetti D, McLeod L, Williams N, Coles T, Tzivelekis S, Meckley LM. Development and validation of the IG Patient Experience with Treatment (IGPET), a novel patient-reported measure for individuals with primary immunodeficiency. Poster presented at the ISPOR 24th Annual International Meeting; May 21, 2019. New Orleans, LA.

OBJECTIVES: Primary immunodeficiency disease (PID) is a genetic condition in which the immune system is impaired or missing. Typical treatment involves lifelong immunoglobulin replacement therapy (IGRT), administered in a home or clinical setting, either via intravenous (IV) or subcutaneous (SC) routes. This study developed and psychometrically evaluated a novel measure of patient experiences with IGRT.

METHODS: Researchers conducted telephone interviews with patients aged ≥17 years in the United States (US) who received IGRT for PID. Results from the concept-elicitation and cognitive-debriefing interviews were used to develop the Ig Patient Experience with Treatment (IgPET). The IgPET, along with the Life Quality Index (LQI) and Treatment Satisfaction Questionnaire for Medication (TSQM)-9, was then administered via online survey to US adults with PID identified through the Immune Deficiency Foundation. Subscale scoring was 0–5 for the IgPET and 0–100 for the LQI and TSQM-9, with higher scores indicating more favorable experiences. Psychometric evaluation of the IgPET was conducted, which included internal-consistency reliability, known-groups validity, and construct validity.

RESULTS: Twenty-one adult patients were interviewed. Overall, patients considered IGRT to be lifesaving rather than burdensome; however, some reported negative impacts. The web survey involved 814 patients, of whom 84% were female and 96% were white. Most received IGRT at home (74%) and received SC therapy (59%). Subscale scores (mean [SD]) were: IgPET Convenience: 3.5 (0.8), IgPET Control: 4.1 (0.7), IgPET Impacts and Interference: 3.4 (0.8); TSQM-9 Effectiveness: 71.3 (19.9), TSQM-9 Convenience: 68.0 (20.9), TSQM-9 Global Satisfaction: 79.7 (19.4); LQI Treatment Interference: 76.2 (18.0), LQI Therapy-related Problems: 71.0 (18.5), and LQI Therapy Settings: 85.6 (16.7). Psychometric properties were acceptable.

The IgPET is a valid measure of patient experience for PID. Generally, patients reported favorable experiences with their IGRT; however, they also identified some areas for improvement in treatment satisfaction (eg, treatment planning, side effects).

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