Abstract
Background and objective: Tapering of biologics dose is a safe and feasible approach for people with rheumatoid arthritis (RA) in remission. However, the appeal of tapering needs to be balanced against the risks of disease flare-up. Little is currently known about how the preferences of people with RA would influence their decision to accept biologics tapering. This thesis aimed to elicit and evaluate the preferences of people with RA for biologics tapering.
Methods: This thesis employed a three-phased mixed-methods study design. In phase 1, people with RA were invited to participate in focus groups (FGs) (n=43) and individual interviews (n=2) to explore their perspectives towards biologics tapering. Thematic analysis was applied to generate themes of what patients considered in their choice of tapering biologic. The next phase described the development of a discrete choice experiment (DCE) survey according to good research practices, which was piloted among patients (n=16). Think aloud (TA) procedures and FGs were employed to establish the feasibility of a DCE as an instrument to elicit preferences for tapering of biologics. In phase 3, participants with RA (n=142) completed an online DCE survey consisting of 14 scenarios, asking their preferences when given three hypothetical treatment options involving varying frequency of biologics dosing, chances of adverse effects, chances of regaining disease control and healthcare service-related features. Preference weights were estimated using a panel mixed logit model.
Results: Thematic analysis revealed five overarching themes describing: (i) fear of the uncertain outcomes of tapering, (ii) prioritising quality of life from continuing biologics over the risk of adverse effects, (iii) inconvenience of taking biologics regularly, (iv) assurance of prompt access to healthcare after disease flare and (v) preferences for involvement in decision-making. The themes were used to guide the subsequent phase of developing attributes for DCE. Findings from TA and FG data indicated the DCE was well-received by participants and was an acceptable instrument to elicit preferences. Most participants understood the context of a DCE, were able to engage with the choice task while employing various decision-making strategies when making their choice. Feedback received were used to improve and prepare the DCE for the next phase. In phase 3, the DCE data revealed that two attributes with the greatest impact on the preferences for tapering were frequency of biologics dosing (mean relative importance:1.0, 95%CI 0.79-1.20) and the chance of disease flare (mean relative importance:0.64, 95%CI 0.49-0.79). Time to see the rheumatology team after a flare was ranked the least important among the seven attributes. Participants were willing to accept a 25.3% to 50.2% increase in the chance of disease flare in exchange for reducing the frequency of treatment, the chance of serious infection and skin cancer. The predicted uptake of biologic tapering was high among people with RA, suggesting biologics tapering was a favoured option.
Conclusions: This thesis addresses an important research gap about how people with RA make decisions and trade-offs between the benefits and risks of tapering their biologics. The evidence presented provides novel insights that have implications for clinical practice and policy making about biologic tapering.