Validation of a treatment satisfaction questionnaire in non-Hodgkin lymphoma: assessing the change from intravenous to subcutaneous administration of rituximab

BACKGROUND: A subcutaneous (SC) formulation of rituximab (MabThera(®)/Rituxan(®)) has been developed that could reduce administration time and improve patient satisfaction with treatment. The Rituximab Administration Satisfaction Questionnaire (RASQ) was created to assess patients’ perceptions and satisfaction with rituximab SC (RASQ-SC) or rituximab intravenous (RASQ-IV). We assessed the content validity and psychometric properties of RASQ in patients with non-Hodgkin lymphoma. METHODS: Face and content validity of RASQ-SC and RASQ-IV were qualitatively assessed using 60-minute combined concept elicitation and cognitive debriefing interviews. Psychometric validation of RASQ (item performance and reliability) was assessed quantitatively against the established Cancer Therapy Satisfaction Questionnaire (CTSQ), using questionnaire data from the PrefMab (NCT01724021) and MabCute (NCT01461928) clinical studies. RESULTS: RASQ-IV demonstrated excellent coverage of concepts relevant to patients’ (n=10) own treatment experiences and no new concepts were identified. Patients’ expectations of rituximab SC were conceptually consistent with items included in the RASQ-SC, suggesting that the tool is also conceptually adequate. In 1,051 patients from PrefMab and MabCute, correlations with domains such as “RASQ: Physical Impacts” and “CTSQ: Feelings About Side Effects”, “RASQ: Physical Impacts” and “CTSQ: Satisfaction With Therapy”, and “RASQ: Satisfaction” and “CTSQ: Satisfaction With Therapy”, achieved moderate-to-high correlations (>0.4) for convergent domains and <0.3 for divergent domains. CONCLUSION: This study supports the qualitative face and content validity and psychometric validity of RASQ-IV and RASQ-SC. Minor revisions were made to the questionnaires to enhance clarity and aid consistent reporting.