OBJECTIVES: Belgium is characterized by its low use of biosimilar products and shifts from off-patent biologicals towards new alternative therapies. Yet, prescribing decisions involved in these observations are poorly understood. This study aims to investigate prescribing choices for off-patent biologicals and biosimilars among Belgian physicians in the ambulatory care.

METHODS: First, a structured literature review to identify factors influencing prescribing choices was performed. Second, the nominal group technique (NGT) was employed with Belgian physicians to consider and validate these factors for off-patent biologicals in the Belgian context. The qualitative data resulting from the literature review and NGT were analyzed using the thematic framework method.

RESULTS: Fifty-three scientific articles that discussed determinants of prescribing choices were identified. Out of these, 17 factors were extracted that determine prescribing decisions. These factors were divided into five categories: product-related factors, personal factors, healthcare system-related factors, patient-related factors, and factors related to the pharmaceutical company or brand. Subsequently, nineteen Belgian physicians from different therapeutic areas participated in the focus group discussions. The group discussions (NGT) revealed that prescribing choices for off-patent biologicals are determined by a complex set of factors. Clinical data, geographical region, working environment, pharmaceutical marketing, patient profile, clinical guidelines, and preference of key opinion leaders (KOL) were considered most influential. Physicians indicated that the importance of these determinants differs depending on product classes or therapeutic domain.

CONCLUSIONS: Multiple factors determine the choice of an off-patent biological or biosimilar product. To increase the prescription of best-value biologicals in the Belgian ambulatory care, a set of synergistic measures is required including information for prescribers and patients, prescribing feedback, quotas, tangible incentives, KOL involvement, regular review of reimbursement modalities, and guidelines regarding pharmaceutical promotion. Policy measures should be tailored to the product-specific context and implemented prior to the changing market environment when biosimilars enter the market.