Background and importance Maintaining persistence is a key element in pharmacotherapy follow-up. Adverse effects of biosimilars may be one of the main causes for discontinuing treatment.
Aim and objectives To analyse persistence as an effectiveness and safety indicator for different biosimilars in immune mediated inflammatory diseases (IMID) in clinical practice.
Material and methods A retrospective study was conducted in a regional hospital with a reference area of 110 000 inhabitants and 230 biological treatments (BT). All patients with an IMID who had received a biosimilar of infliximab, etanercept or adalimumab from the first biosimilar’s entry in the pharmacotherapeutics guide until February 2020 were included. Variables studied were demographic data (gender, age), medical speciality, previous treatments and time receiving the biosimilar. Reasons for discontinuation and activity of the disease were registered. Data collection was done with SAVAC, an electronic prescription system. Statistical analysis was performed using SPSS Statistics V.22. Categorical variables are shown as percentages and quantitative variables as mean (SD).
Results 64 patients (27.8% BT) were included: 28 (43.8%) were men and mean age was 43.7 (SD 16.3) years. 26 (40.6%) patients had received previous BT, most of them with an anti-TNF (53.8%). Only 11 (17.2%) patients switched from the original to the biosimilar drug. Distribution by drug was: 27 (42.2%) infliximab, 21 (32.8%) etanercept and 16 (25.0%) adalimumab. Distribution by medical speciality was: 34 (53.1%) digestology, 26 (40.6%) rheumatology and 4 (6.3%) dermatology.
31 (48.4%) patients stopped or changed treatment: 13 (41.9%) infliximab, 12 (38.7%) etanercept and 6 (19.4%) adalimumab. Reasons were: 14 (45.2%) adverse effects, 14 (45.2%) inefficacy and 3 (9.6%) other reasons, mainly loss to follow-up. Persistence of treatment was 26 (SD 31.2) weeks. Adverse effects causing discontinuation of the biosimilar were: 3 (16.6%) cases of pain, 2 (11.1%) infections, 2 (11.1%) hypersensitivity reactions, 2 (11.1%) headache, 1 (5.6%) dyspnoea, 1 (5.6%) swelling, 1 (5.6%) asthenia, 1 (5.6%) dizziness, 1 (5.6%) diarrhoea, 1 (5.6%) arthralgia, 1 (5.6%) skin lesions, 1 (5.6%) pruritus and 1 (5.6%) lupus drug induced.
33 (51.6%) treatments remained active: 15 (45.4%) infliximab, 9 (27.3%) adalimumab and 9 (27.3%) etanercept. Persistence of treatment was 55 (SD 39.6) weeks. 27 (81.8%) patients were in remission, 3 (9.1%) presented low activity and 3 (9.1%) moderate activity.
Conclusion and relevance Patients that changed or stopped taking a biosimilar had an average treatment of 6 months. The most common reasons were adverse effects and inefficacy. Regarding adverse effects, 50% were subjective symptoms. A possible nocebo effect could not be discarded. Patients who continued with a biosimilar had a persistence of more than 1 year.
Conflict of interest No conflict of interest
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