Table 1.

Types and sources of variation in delivery of healthcare

	Caused by biological and/or patient influence variation (in anatomy, pathology and patient preference)	Caused by suboptimal availability and/or use of service resources	Caused by suboptimal availability and/or use of EVAR resources
Intended	The monitoring frequency may depend on aneurysm size and growth rate. Patients having an aorta anatomically unsuited for EVAR. Patients being unsuited for open surgery due to comorbidities. Female patients being operated at a smaller aneurysm diameter than male patients. Life expectancy was a contributing factor in surgical decision-making.	Delays due to waiting lists at the radiological units radiological report turnaround time waiting lists for additional tests such as heart and lung exams. The described delays differed (a) within each hospital and (b) across units/hospitals. The management of these delays was particularly evident in the university hospital's workflow.	Delays due to accessibility to the EVAR service: the local surgeon had to refer eligible candidates to the vascular surgery service at the university hospital. Delays in the subsequent patient trajectory depended on the latter's process time. Delays due to lack of professional capacity—for example, when EVAR-skilled personnel were on vacation.
Unintended	Patient in need of EVAR suitability assessment within a few days to complete the decision on whether to operate. Non-planned, extra workload in information processing due to patients preferring to have their CT exam/tests at private institutes.	Delayed decision due to: Patients seeking to coordinate their own healthcare—for example, when a patient rescheduled his CT exam to take place on the same day as the clinical consultation. As a consequence, the patient was not informed about the surgeon's decision before 2–3 days later (the surgeon had to see the CT result).	Delayed decision due to: Patient not showing up at the scheduled appointment. Health personnel failing to act: eg, (1) a CT exam–performed at outside units–was not routed to EVAR suitability assessment in timely advance of the clinical consultation; (2) one patient was not enrolled in the surveillance programme at the time of the discovery of aneurysm.

EVAR, endovascular repair.