Investigating the mechanisms behind behavioural strategies to improve medicines adherence

Medicines non-adherence is a major health policy challenge affecting almost 50% of patients with chronic disease, leading to massive wastage and sub-optimal patient outcomes (WHO, 2003). As such, there is significant demand for initiatives and tools to support and foster adherent behaviours, particularly for individuals dependent on regular long-term medication regimes to maintain or improve their health. It has even been suggested that the potential impact of improving the effectiveness of new and current adherence interventions, may be greater than any specific improvement in medical treatment (Haynes et al., 2002).
Increasing the number of individuals who consistently and correctly self-administer medicines, exactly as prescribed, requires long-term, widespread behaviour change and habit formation. As a result, there is significant scope for the application of behavioural science to inform current and new interventions designed to support patients to take their medication as prescribed.
The effectiveness of low-cost behavioural interventions to increase healthy preventative and protective health behaviours has been widely investigated to varying degrees of success. An intervention can be considered "behavioural" if it instrumentally utilises research, theory, and insights from economics and psychology on human choice, decision-making and behaviour.
Recent evidence suggests that patients who sign a commitment to take a new medication, when the new medicine is first dispensed, are significantly more likely to be adherent to their medicines. However, this result was conditional on the message, highlighting the importance of adherence, that was paired with the commitment (Jachimowicz et al., 2019).
These results suggest that behavioural interventions (or behavioural "nudges") may be a useful new tool for promoting public health initiatives, to enhance pharmacy practice and improve patient outcomes at minimal cost or effort from the perspective of pharmacy practice. However, the prospects for using such approaches more widely and effectively is currently limited by poor understanding of why some nudges work and others don't; why one nudge might work in some contexts and not others; or how nudges might impact different patient groups. Hence, in order to exploit the potential power of nudge-based tools to enhance pharmacy practice, further work is required to understand the mechanisms at work behind successful nudges.
My PhD research investigates the mechanisms behind successful nudges to improve medicines adherence. We employ a randomised controlled trial within 60 Boots community pharmacies to test four different behavioural nudge strategies against a "business as usual" control group. Our strategy allows us to investigate whether it is possible to replicate and improve upon Jachimowicz et al.'s (2019) results, and unpick potential mechanisms driving changes in patient behaviour in response to the nudges.
Alongside this project we have conducted a series of online experiments to evaluate the reliability of a standardised self-reported adherence questionnaire (the 5-item Medicines Adherence Rating Scale developed by Thompson et al. (2000)) to accurately evaluate the effect of a behavioural intervention on self-reported adherence. The online experiments allow us to detect whether certain behavioural strategies prompt subjects to over-report their adherence and estimate the size of any additional reporting bias.