P114 The cost of caution: evaluating the utility and financial impact of procollagen-3 N- terminal peptide monitoring in methotrexate-treated patients

Abstract

Procollagen-3 N-terminal peptide (P3NP) is a serum biomarker for liver fibrosis recommended by the BAD guidelines for monitoring methotrexate-treated patients with psoriasis. However, metabolic syndrome may confer greater fibrosis risk than methotrexate exposure alone. This audit evaluated adherence to the BAD’s P3NP monitoring guideline and examined the cost implications. We retrospectively analysed P3NP monitoring outcomes and costs in dermatology patients receiving methotrexate from hospital pharmacies across three regional hospitals (April to September 2024). Patients treated for < 6 months were excluded. Blood test costs at 3 and 6 months after initiation or dose change were analysed. In total, 53 patients were identified (mean age 43.7 years, range 6–84; 51% male). The diagnoses were psoriasis (33, 62%), eczema (11, 21%) and other dermatoses (9, 17%). Only 49% (16) of patients with psoriasis received guideline-concordant monitoring. Four patients received inappropriate P3NP testing: three with eczema and one with psoriatic arthritis (PsA). P3NP was elevated in 64% of tested patients (28 of 44), predominantly in those with psoriasis (26 of 28, 93%; including 1 with PsA). Of 17 patients with available data, 13 (76%) were overweight. Nineteen of the 28 patients (68%) had metabolic syndrome risk factors. Raised P3NP led to FibroScans in 6 cases, whereas 22 required no management change. The total 6-month blood-test cost was £2633. Additional tests (folate, vitamin B12) accounted for 10.9% (42 of 385) of investigations; only 12% (5 of 42) had documented indications, suggesting potential savings of £182. A single P3NP test costs £22.43; 30 inappropriate tests (PsA, skin conditions other than psoriasis and/or at inappropriate frequency) equated to £673 in avoidable expenditure. FibroScans (£35 per procedure) could save £54.72 per patient annually. Elevated P3NP had limited clinical impact and correlated more strongly with metabolic risk factors rather than methotrexate exposure. Risk-stratified monitoring using Fib-4, NICE-recommended fibrosis scoring and FibroScans may improve cost-effectiveness and better target true liver disease risk in methotrexate-treated dermatology patients.