Theme: Social Science & Policy Research Year: 2019
Background: Increasing access and linkage to care for hepatitis C (HCV) are fundamental
requirements for achieving the WHO target of elimination by 2030. The SuperDOT-C research
programme designed and evaluated an HCV test and treat pathway delivered with direct-acting
antivirals, through community pharmacists. As part of the process evaluation of the intervention,
causal loop diagramming (CLD) was used as a tool to help understand complexity and generate
hypotheses about causal mechanisms.
Methods: A systematic literature review and series of community-based participatory research
activities were undertaken to inform the design and understand the acceptability of the SuperDOT-C
intervention. Qualitative work included implementation of seven focus groups with service users and
carers (41 participants), discrete choice experiment with service users (103 participants), semistructured interviews on service acceptability with service users (14 participants) and staff providers
(36 participants). All transcripts were thematically analysed.
A causal loop diagram was constructed with contributors defined as: health worker performance;
health care environment; patient behaviors and attitudes; patient environment. Components were
identified then assigned polarity and arranged into feedback loops associated with the contributors,
with reinforcing (R) and balancing (B) effects. The resultant CLD was used to examine system
components and the dynamic relationships between them.
Results: 34 components were identified from the literature review and qualitative work and plotted
onto a CLD. The CLD was reviewed and two reinforcing loop and three balancing loops determined.
The reinforcing loops described positive patient relationships, proximity to the community and role
enhancement as factors promoting uptake of the care pathway. The balancing loops described
factors such as experience of stigma and fear of treatment side-effects, but also the factors such as
homelessness, healthcare policy and budgetary restraints.
Conclusion: A systems-thinking approach using CLD is helpful in the evaluation of complex public
health interventions and forming hypotheses about causal mechanisms.
Disclosure of Interest Statement: SuperDOT-C was funded by the Scottish Government with free
drug provided by Bristol Myers-Squibb and Gilead Sciences Inc