OBJECTIVES: Qualitative research enables an in-depth understanding of the patient experience, however, attaining a sufficient sample size to determine the content validity of a Clinical Outcomes Assessment (COA) instrument can be challenging, especially in rare diseases. The FDA Patient Focused Drug Development guidance mentions surveys as an appropriate method to inform content validity. We utilized survey data along with concept elicitation (CE) interview data to achieve concept confirmation to support content validity for three COAs in the SCA population.

METHODS: A cross-sectional survey was completed by 147 patients with Cerebellar Ataxia (CA). Respondents were asked to describe all the symptoms and impacts associated with their disease. CE interviews were conducted with SCA patients. Concept confirmation was evaluated by mapping concepts collected from both data sources against the three COAs of interest (f-SARA, PIFAS, FARS-ADL).

RESULTS: All concepts in the COAs were endorsed by the surveys and/or interviews. 65 signs/symptoms (16 domains) and 56 impacts (7 domains) were reported across sources. The domains were consistent between interviews and survey (e.g., walking, stance/balance, etc.), noting a depth of information was captured for individual concepts in the survey as compared to the interviews alone (i.e., 29 signs/symptoms and 15 impacts were elicited from the survey only). For example, while the domain “stance/balance” was endorsed by both sources, interviewees and survey participants reported “balance (e.g., trouble keeping balance)” while only survey participants reported “coordination”, highlighting a specific dimension of the domain not captured by the interviews alone. The combination of survey and interview data sources strengthened the concept relevance, highlighting what is important to patients.

CONCLUSIONS: Survey data was combined with qualitative interviews as a mixed method approach to support the content validation of three SCA COA instruments used in a clinical trial. This approach may be preferable to elicit a more comprehensive perspective of the patient experience.