Discontinuation of anti-TNF-alpha treatment due to blood test abnormalities and cost-effectiveness of alternate blood monitoring strategies

Background: There is no evidence base supporting the use of six-monthly monitoring blood tests for the early detection of liver, blood, and renal toxicity during established anti-TNF-alpha treatment. Objectives: To evaluate the incidence and risk factors of anti-TNF-alpha treatment cessation due to liver, blood, and renal side-effects and, to estimate the cost effectiveness of alternate intervals between monitoring blood tests.Methods: A secondary-care based retrospective cohort study was performed. Data from the British Association of Dermatologists Biologic and Immunomodulators Register were used. Patients with at-least moderate psoriasis prescribed their first anti-TNF-alpha treatment were included. Treatment discontinuation due to monitoring blood test abnormality was the primary-outcome.Patients were followed-up from treatment start to the earliest of outcome, drug discontinuation, death, five years, or 31/07/2021. The incidence rate and 95% confidence intervals (CIs) of anti-TNF-alpha discontinuation with monitoring blood test abnormality was calculated. Multivariate Cox regression was used to examine the association between risk-factors and outcome. A mathematical model evaluated costs and quality-adjusted life years (QALYs) associated with lengthening the time between monitoring blood tests during anti-TNF-alpha treatment.Results: The cohort included 8,819 participants (3,710 (42.1%) female, mean age (standard deviation) 44.76 (13.20) years) that contributed 25,058 person-years of follow-up and experienced 125 treatment discontinuations due to monitoring blood test abnormality at an incidence rate (95%CI) of 5.85 (4.91-6.97)/1,000 person-years. Of these, 64, and 61 discontinuations occurred within the first year, and after the first year of treatment start, at an incidence rate (95% CI) of 8.62 (6.74-11.01) and 3.44 (2.67-4.42)/1000 person-years respectively. Increasing age in years, diabetes, and liver disease associated with anti-TNF-alpha discontinuation with monitoring blood test abnormality with adjusted Hazard Ratio (95%CI) of 1.02 (1.01-1.04), 1.68 (1.00-2.81), and 2.27 (1.26-4.07) respectively. Assuming a threshold of £20,000 per QALY gained, no monitoring was most cost-effective but all extended periods were cost-effective compared to three monthly or six-monthly monitoring.Conclusion: Anti-TNF-alpha drugs were uncommonly discontinued due to abnormal monitoring blood tests after the first year of treatment. Extending the duration between monitoring blood-tests was cost-effective. Our results produce evidence for specialist society guidance to reduce patient monitoring burden and healthcare costs