Developing and pre-testing a measure of quality of life for people with primary sclerosing cholangitis (PSC) in the UK

Background: Primary sclerosing cholangitis (PSC) is a rare disease of the liver and bile ducts which can impact on quality of life (QoL). This research aimed to develop and pre-test a measure of QoL for people with PSC (PwPSC) in the UK. Methods: The study followed a two-stage mixed-methods design, drawing on existing guidance for tool development. Stage 1 identified QoL issues of relevance to PwPSC from an online survey and literature review of relevant QoL tools. Consensus on how to reliably stage PSC is lacking, so six categories of disease severity/co-morbidities were hypothesised, including: co-morbid inflammatory bowel disease, awaiting liver transplant, PSC-related cancers. Issue relevance, importance and phrasing were explored with PwPSC and clinicians in an empirical study. Following the development of a conceptual framework, the issues list was refined and the provisional UK-PSC-QoL constructed. Stage 2 pre-testing involved exploring item acceptability, comprehension, relevance, redundancy, and response distributions with UK PwPSC grouped in an expanded eight categories; the two least severe Stage 1 categories were each subdivided into mild and moderate-severe. Results: Stage 1 identified 396 QoL issues, explored with 28 PwPSC and 11 clinicians. Following issue reduction, 83 items were constructed in the six domains of the UK-PSC-QoL, including a separate six-item module for PwPSC with a stoma. Stage 2 pre-testing was conducted with 60 PwPSC who had comments about the wording of 54 items, mostly due to item ambiguity/clarity. One positive item had an unexpectedly positive skew. Fifty-five items are recommended for retention, 22 items modified to address problematic phrasing, six items deleted, and one new item added. Conclusion: The revised measure comprises 66 items in five domains, complemented by a six-item stoma module and an eight-item experience of care and treatment module. The measure remains provisional and recommended modifications require further testing in larger samples of PwPSC.