The causal role of low supervisor support in accidental blood exposure among hospital healthcare workers: a Directed Acyclic Graph (DAG) analysis of the STRIPPS cohort

BackgroundAccidental blood exposures (AEB) are a major occupational hazard for healthcare workers (HCWs), with risk of bloodborne pathogen transmission. While organisational factors are known to influence safety, the specific causal pathways linking management quality to AEB risk remain poorly characterised. ObjectivesTo investigate the causal pathways linking organisational factors, particularly supervisor support, to AEB risk among HCWs through stress and fatigue mediators using Directed Acyclic Graph (DAG) analysis. MethodsSecondary analysis of the STRIPPS cohort study including 32 wards across four Paris university hospitals (n=730 HCWs). A DAG was constructed based on a literature review and previously published multivariate analyses to model causal relationships between organisational factors, psychological mediators, and AEB outcomes. ResultsAEB incidence was 4.1 per 100 visits overall, highest in intensive care units (7.1/100). DAG analysis showed that low supervisor support increased AEB risk through both direct and indirect pathways. Literature evidence indicated a protective effect of supervisor support on both stress and fatigue, while these psychological factors are strongly associated with increased AEB risk. Additional organisational factors including irregular work schedules, rotating shifts, and use of external personnel contributed to elevated AEB risk. Individual factors such as work overcommitment and presenteeism further amplified stress and fatigue pathways. The analysis explored multiple converging pathways from organisational and individual factors through psychological mediators to AEB risk. ConclusionsLow supervisor support drives AEB risk through multiple interconnected pathways affecting stress and fatigue. Interventions targeting organisational support and psychological wellbeing could substantially reduce occupational injury risk among HCWs. HighlightsO_LIWhat is already known about this subject? O_LIAccidental blood exposures (AEB) are a major occupational hazard for healthcare workers (HCWs), with significant risks of bloodborne pathogen transmission and psychological distress. C_LIO_LIOrganisational factors, including leadership and safety culture, are known to influence workplace safety, but their specific causal pathways to AEB remain poorly understood. C_LIO_LIStress and fatigue are recognised as mediators between work conditions and safety outcomes, but their roles in AEB have not been systematically modelled using causal methods. C_LI C_LIO_LIWhat are the new findings? O_LIUsing a Directed Acyclic Graph (DAG) approach, we identified that low supervisor support increases AEB risk through both direct and indirect pathways mediated by stress and fatigue. C_LIO_LIFatigue showed a stronger association with AEB (OR 2.94-4.25) than stress (OR 1.12-1.53), highlighting its critical role in occupational safety. C_LIO_LISickness presenteeism and work overcommitment were identified as key individual-level amplifiers of stress and fatigue, further increasing AEB risk. C_LIO_LIIrregular work schedules and use of interim staff were organisational factors with substantial effects on AEB risk (RR > 3.0). C_LI C_LIO_LIHow might this impact on policy or clinical practice in the foreseeable future? O_LIHealthcare organisations should prioritise supervisor training to improve supportiveness, which could reduce both psychological strain and AEB incidents. C_LIO_LIFatigue risk management systems and scheduling optimisations should be implemented to mitigate the strong effects of irregular shifts and long hours. C_LIO_LIPolicies discouraging presenteeism and promoting mental health support could break the cycle of fatigue and injury among HCWs. C_LI C_LI