Process of care and outcomes in patients with peripheral arterial disease

Background: We investigated the association of process of care measures with adverse limb and systemic events in patients with peripheral arterial disease (PAD). Methods: We conducted a retrospective cohort study of patients with PAD, as defined by an ankle-brachial index (ABI) < 0.9. The index date was defined as the date, during 1995 to 1998, when the patient was seen in the Michael E. DeBakey VA Medical Center noninvasive vascular laboratory and found to have PAD. We conducted a chart review for process of care variables starting 3 years before the index date and ending at the time of the first event or the final visit (December 31, 2001), whichever occurred first. We examined the association between PAD process of care measures, including risk factor control, and prescribing of medication, with time of the patient's first major limb event or death. Results: Of the 796 patients (mean age, 65 +/- 9.9 years), 230 (28.9% experienced an adverse limb event (136 lower-extremity bypass, 94 lower-extremity amputation), and 354 (44.5%) died. Of the patients who died, 247 died without a preceding limb event. Glucose control was protective against death or a limb event with a hazard ratio (HR) of 0.74 (95% confidence limits [CL] 0.60, 0.91, P = 0.004). African Americans were at 2.8 (95% CL 1.7, 4.5) times the risk of Whites or Hispanics for an adverse limb event. However, this risk was no longer significant if their glucose was controlled. For process measures, the dispensing of PAD specific medication (HR 1.4, 95% CL 1.1, 1.7) was associated an increased risk for an adverse outcome. Conclusions: Our data suggest that glucose control is key to reducing the risk for adverse outcomes, particularly limb events in African Americans. Certain process of care measures, as markers of disease severity and disease management, are associated with poor outcomes in patients with PAD. Further work is needed to determine the role of early disease intervention to reduce poor outcomes in patients with PAD.