Development and validation of a measure to assess patient experience of needling of arteriovenous fistulas or grafts for haemodialysis access: the NPREM

Abstract

BACKGROUND: Needling is a key step in haemodialysis. Research suggests that needling experience is sub-optimal; however, no validated measure exists to inform improvements. We addressed this by developing the Needling Patient Reported Experience Measure (NPREM). METHODS: We used mixed methods and co-production. All participants were adults with working fistulas/grafts from eight UK kidney centres. Phase 1 involved developing concepts and items: in interviews (n = 41), we explored patients' needling experience and identified key aspects of needling using thematic analysis. This informed the 98-item NPREM(v0.1). Phase 2 was piloting the measure: cognitive interviews (n = 16) assessed face validity. Items were amended or removed, yielding a 48-item NPREM(v0.2). A pilot survey (n = 183) examined initial psychometric properties. NPREM(v0.2) showed good internal consistency (Cronbach's alpha = 0.95). Review of analyses resulted in a 35-item NPREM(v0.3). Phase 3 involved evaluating the measure's dimensionality, validity and reliability: patients (n = 468) completed the NPREM(v0.3), Vascular Access Quality of Life (VASQoL), EuroQol 5-Dimension-5-Level (EQ-5D-5L) and Patient Activation Measure (PAM), with a sub-set completing a follow-up NPREM (n = 99). Items were evaluated with 28 items retained in the NPREM(v1.0). Confirmatory factor analysis confirmed a unidimensional model fit (comparative fit index = 0.899). Validity of the NPREM(v1.0) was good [convergent: VASQoL (r = 0.60) and overall experience (r = 0.79); divergent: EQ-5D (r = -0.31), EQ-5D visul analogue scale (r = 0.24) and PAM (r = 0.17)]. Test-retest scores were strongly correlated (r = 0.88), demonstrating high reliability. Known-groups validity was demonstrated between centre scores [range 5.21 (standard deviation 1.20) to 5.94 (0.75)]. CONCLUSION: The NPREM measures patient experience of needling for haemodialysis. It offers kidney services a means of assessing needling experience, informing patient-focused clinical and service improvements.