OBJECTIVES: To analyse the changes in the reimbursed cost, prices, and utilization of biological medicines for a 5-year time horizon, encompassing three major arthropathic diagnoses (RA, PsA, AS) from the point of view of third-party payer in Bulgaria.

METHODS: National; population based; macroeconomic; top-down budget analysis was performed based on officially published sources about the number of inhabitants, reimbursed diagnoses and medicines, reimbursed cost, treated patients, and prices of medicines. Utilisation of medicines was calculated in DDD per 1000/inh/day.

RESULTS: We note a substantial increase of 41% in the number of patients treated with biological medicines in the 5-year period. Reimbursement cost of biologicals increased by 21%, however, per patient reimbursement costs per diagnosis fell by 40% due to price decreases. Out of 21 reimbursed diagnoses, we saw a significant difference in prevalence (612 SD in 2016 to 1216 SD in 2020; p<0.05). Rheumatoid arthritis accounted for 2736 patients in 2016 and increased by 131% to 4662 patients in 2020, ankylosing spondylitis with 1933 patients in 2016 reached 3196 patients by 2020, and psoriatic arthropathies with 1128 patients took the third place with a 75% increase. The cost of therapy of RA is with highest value accounting for appr. 15mill Euro in 2016, subsequently growing by 5 Mill Euro at the end of the period.

Comparison of the utilisation in DDD/1000inh/day shows that only 2 INNs decreased in terms of their utilisation (infliximab and rituximab). All INNs experience a nearly two-fold increase in their utilisation - from 0.5244 to 0.9252 DDD/1000inh/day for 5-years period.

CONCLUSIONS: The economic analysis shows an important place of biologicals for arthropathic diseases therapy, introduction of biosimilars lead to prices and cost decreases, and more patients could benefit from its novelty.