SLR - October 2018 - Yehia Elebrashi

Ankle-Brachial Index, Toe-Brachial Index and Cardiovascular Mortality in Persons with and Without Diabetes Mellitus

Reference: Hyun S, Forbang NI, Allison MA, Denenberg JO, Criqui MH, Ix JH. Ankle-Brachial Index, Toe-Brachial Index and Cardiovascular Mortality in Persons with and Without Diabetes Mellitus. J Vasc Surg. 2014 Aug;60(2):390-5. doi: 10.1016/j.jvs.2014.02.008. Epub 2014 Mar 21.

Scientific Literature Review

Reviewed By: Yehia Elebrashi, DPM
Residency Program: Maricopa Medical Center, Phoenix, AZ

Podiatric Relevance: The purpose of the reviewed study was to draw correlation of cardiovascular disease (CVD) mortality rates over a seven-year follow-up period relative to individual vascular studies, ankle-brachial indices (ABIs) and toe-brachial indices (TBIs) in patients with and without diabetes. The authors hypothesized that low TBIs had a stronger association with CVD mortality than low ABIs, and that these differences were more pronounced in patients living with diabetes. It is vital for the podiatric provider/surgeon to be knowledgeable of the recommendations and guidelines of the aforementioned associations to properly diagnose PAD and appropriately provide standard of care surgical and nonsurgical treatment modalities.

Methods: Four hundred sixty-nine participants were included in the study, seen in the previous 10 years for noninvasive lower-extremity arterial testing at the San Diego VA Medical Center or the UCSD Medical center vascular laboratory. Previously recorded ABI, TBI and CVD risk factor data was utilized for assessment. Participants were categorized into four groups based on clinical ABI cut points of 1.30 and TBI scores of 1.08. Cox proportional hazard models were used to evaluate association of each category with time to CVD death. Statistically significant interactions were evaluated for association of ABI and TBI categories in diabetic and nondiabetic participants separately.

Results:
•    Mean ABI 0.83 ± 0.28
•    Mean TBI 0.60 ± 0.24
•    Claudication symptoms 139 individuals (30 percent)
•    15 (3 percent) with at least one leg ABI <0.40 (critical limb ischemia)
•    CVD mortality risk did not differ significantly across these groups
•    Lower ABI scores generally associated with lower TBI scores
•    Median 7.0 years of follow-up, 158 CVD deaths, 75 (47 percent) occurred in patients living with diabetes
•    Nondiabetics, lower ABI levels associated with step-wise increase in CVD death risk
•    Nondiabetics, no CVD death events observed in group ABI >1.30
•    In diabetics and nondiabetics, stepwise lower TBI scores associated with progressively higher risk of CVD death
•    Participants in highest TBI score category (>1.08) at lowest risk of CVD death irrespective of diabetes status, similar in models adjusted for age and sex and in fully adjusted models

Conclusions: Based on the study findings, the author made the following conclusions: ABI measurements associated with CVD mortality differs among those with and without diabetes, and nondiabetic patients with lower ABI measurements are at a step-wise increased risk for CVD death. Additionally, patients with diabetes and high ABI levels are at higher risk for CVD death than “normal” ABI levels (0.90-1.30), which is not observed using the TBI. It is imperative to have a greater understanding in the screening and diagnosis processes regarding PAD, especially in the diabetic population. It is likely that many people have missed or improperly diagnosed their conditions, which ultimately may lead to suboptimal treatment measures and outcomes. The key point is to provide each patient with due diligence in his or her work-up, in this case, specifically PAD, as results may drastically alter treatment options whether surgical or nonsurgical. The proposed recommendations will ensure providing standard of care and improving the likelihood of optimal outcomes.

Educational Opportunities

Upcoming