Development of a Patient Reported Outcome Measure of Side Effects for Patients Taking Calcineurin Inhibitors: The FACIT-CNI-Ntx.

Rationale & objective: Valid measures of side effects are important to inform clinical use of calcineurin inhibitors (CNIs). This study sought to develop and establish the content validity of a PRO measure to capture side effects among kidney transplant recipients taking CNIs.

Study design: Qualitative interviews for concept elicitation and cognitive debriefing.

Setting & participants: Participants enrolled in the qualitative study were adults who received a kidney transplant ≤5 years earlier and were currently taking a CNI for immunosuppression.

Analytical approach: Concept elicitation interview data were analyzed by developing a codebook from a list of symptoms described by participants that they attributed to CNIs or their immunosuppression regimen and by applying the constant comparative approach separately by two coders. The most bothersome and important side effects reported by participants were used to select existing PRO items. Cognitive debriefing examined item comprehensibility, comprehensiveness, and relevance.

Results: Among 24 participating patients, 12 underwent concept elicitation interviews. Most (n=10) participants reported neurological or cognitive CNI side effects and a majority of those (n=6) reported that neurological and cognitive side effects were the most bothersome adverse consequences of therapy. Based on these findings, 16 items were either selected from the Functional Assessment for Chronic Illness Therapy (FACIT) PRO item library or were newly written. These items were refined and reduced to 13 for cognitive debriefing that was completed by 18 participants. These items were organized into two scales: Tremors and Cognitive Side Effects.

Limitations: Though a diverse set of patients participated, they were not representative of all recipients of kidney transplants. The PRO's reliability, convergent and known-groups validity, and responsiveness to change were not evaluated. Symptoms could not be definitively attributed to CNIs.

Conclusions: A newly developed PRO measure, the Functional Assessment of Chronic Illness Therapy-Calcineurin Inhibitor-Neurotoxicity (FACIT-CNI-Ntx), captures important side effects among patients receiving CNIs.