Background
System factors contributing to preventable harm in vascular patients have not been previously reported in detail. The aim of this exploratory mixed-methods study was to describe vascular surgeons' perceptions of factors contributing to adverse events (AEs) in arterial surgery. A secondary aim was to report recommendations to improve patient safety.

Methods
Vascular consultants/registrars working in the British National Health Service were questioned about the causes of preventable AEs through survey and semi-structured interview (response rates 77% and 83%, respectively). Survey respondents considered a recent AE, indicating on a 5 point Likert scale the extent to which various factors from a validated framework contributed toward the incident. Semi-structured interviews were conducted to obtain detailed accounts of contributory factors, and to elicit recommendations to improve safety.

Results
Seventy-seven surgeons completed the survey on 77 separate AEs occurring during open surgery (n = 41) and in endovascular procedures (n = 36). Ten interviewees described 15 AEs. The causes of AEs were multifactorial (median number of factors/AE = 5, IQR 3-9, range 0–25). Factors frequently reported by survey respondents were communication failures (36.4%; n = 28/77); inadequate staffing levels/skill mix (32.5%; n = 25/77); lack of knowledge/skill (37.3%; n = 28/75). Themes emerging from interviews were team factors (communication failure, lack of team continuity, lack of clarity over roles/responsibilities); work environment factors (poor staffing levels, equipment problems, distractions); inadequate training/supervision. Knowledge/skill (p = .034) and competence (p = .018) appeared to be more prominent in causing AEs in open procedures compared with endovascular procedures; organisational structure was more frequently implicated in AEs occurring in endovascular procedures (p = .017). To improve safety, interviewees proposed team training programmes (5/10 interviewees); additional protocols/checklists (4/10); improved escalation procedures (3/10).

Conclusion
Vascular surgeons believe that AEs in arterial operations are caused by multiple, modifiable system factors. Larger studies are needed to establish the relative importance of these factors and to determine strategies that can effectively address system failures.