Objectives Biologicals play a crucial role in managing some of the rheumatological diseases, thus it is important for clinicians, healthcare institutions and policy-makers to understand why biologicals are initiated or refused so as to make better decisions to improve patients’ disease outcomes. Although there have been many studies investigating factors associated with the initiation of biologicals for patients with rheumatological conditions, there have been no systematic reviews that provide a comprehensive summary. We aim to provide a summary of factors associated with biologicals' initiation for patients with rheumatological conditions.

Methods We performed a literature search in PubMed, Embase and PsycINFO. We identified and screened studies according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Factors were presented according to patient, disease-related, therapy-related, healthcare team-related and system in-place factors.

Results A total 1755 articles were reviewed and 24 articles were found to be relevant to our objective. Forty four factors reviewed were placed into five main categories: patient factors (n=13); disease-related factors (n=11); therapy-related factors (n=7); healthcare team-related factors (n=4) and system in-place-related factors (n=9). The factors studied by the published papers found to be associated with decisions to initiate biologicals varied widely.

Conclusion Forty two factors of five different categories were found to be associated with biologicals' initiation for patients with rheumatological conditions. Clinicians need to be mindful of the complex nature of these factors to optimise therapy of patients with rheumatological conditions. Healthcare institutions and policy- makers ought to be aware of any potential barriers to successful biologicals' treatment and address them accordingly.