Hidden dangers revealed by misdiagnosed peripheral arterial disease using ABPI measurement

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Abstract

Aim

The aim of this study was to compare ankle brachial indices (APBI) with pedal waveforms utilizing the continuous wave Doppler in a population with diabetes mellitus.

Methods

A prospective study design was employed to investigate the ABPI in a cohort of 49 people with type 2 diabetes mellitus. ABPI assessment was completed using a portable handheld Doppler and ankle pressures of <0.9 were taken as suggestive of peripheral arterial disease (PAD). Arterial spectral waveforms in each foot were also recorded and compared to the ABPI readings.

Results

Inconsistencies were identified between ABPIs and waveform interpretations in the study population. Approximately 35% of subjects had inconsistencies between their ABPI result and waveform interpretation in their right or left foot.

Conclusions

Both ABPIs and Doppler waveforms should be used in the assessment of people with diabetes in order to screen for PAD. This would ensure an accurate assessment of PAD and would allow initiation of appropriate secondary risk factor control measures.

Introduction

Peripheral arterial disease (PAD) is a condition characterized by blockage or narrowing of the main arteries, most commonly the superficial femoral artery in the thigh or the common and external iliac artery in the lower abdomen which carry blood to the legs [1].

The prevalence of PAD ranges from 3% to 10% in the general population, increasing to 15–20% in individuals over 70 years of age [2]. However, as many as 50% of these are asymptomatic [3]. Furthermore, it has been reported that Mediterranean countries have a higher prevalence of PAD than other western and northern European counterparts [4].

PAD is a significant public-health problem. Only approximately 30% of people with PAD live up to 15 years after the initial diagnosis [5] with those at highest risk being over the age of 50 years and have risk factors including diabetes, obesity, dyslipidemia and smoking history. Only approximately 25% of people with PAD undergo treatment for this condition. This low percentage is largely attributed to the fact that most people are not aware that they are living with this condition. The majority of people with diabetes and PAD are asymptomatic and frequently do not experience claudication symptoms due to peripheral neuropathy. Furthermore one-third of these asymptomatic people are said to have complete occlusion of a major leg artery making it more likely for them to present with an ischemic ulcer which may lead to gangrene and later amputation [6].

The most widely used test for diagnosing PAD in a clinical setting is the ankle brachial pressure index (ABPI). The ABPI has been reported to be almost 100% specific in identifying healthy individuals and an ABPI < 0.9 is approximately 95% sensitive in detecting arteriogram positive PAD [7]. The ABPI consists of a noninvasive, quantitative measurement of the patency of the lower extremity arterial system. This is a validated and reproducible test which consists of a simple measurement which can be performed in any health care professional clinic with inexpensive equipment consisting of a blood pressure cuff and a Doppler ultrasonic sensor [8]. This involves measuring the systolic blood pressure in the ankles and arms and then calculating a ratio. The American Diabetes Association Consensus statement [9], reported the ABPI as a non-invasive method for evaluating PAD and that in contrast to the variability of pulse assessment and the nonspecific nature of information obtained via history and other components of physical examination, the ABPI is reproducible and reasonably accurate. However, it should be noted that in the evaluation of an individual there may be errors and that the reliability of any diagnostic test is dependent on the prior probability of disease (Bayes’ Theorem) [10]. This is mainly a result of poorly compressible arteries due to the presence of medial arterial calcification, thus rendering the diagnosis of PAD by ABPI alone less reliable and inaccurate due to artefactually raised occlusion pressures especially in people with diabetes mellitus and end stage renal failure.

This study aimed to evaluate the occurrence of peripheral arterial disease in a hospital setting using ABPI in people with type 2 diabetes mellitus as recommended by the International Working Group on the Diabetic Foot [11]. A further aim was to compare the findings of the arterial waveform interpretation in conjunction with the ABPI readings in order to determine whether a correlation between the two exists.

Section snippets

Subjects, materials and methods

The data presented in this study was part of a prospective study which was conducted in a tertiary referral hospital setting in Malta. A convenience cohort of the first forty-nine subjects was enrolled for this investigation. This study was approved by the University Research Ethics Committee and all participants provided informed consent before any data collection. All investigations were carried out in accordance with the principles of the Declaration of Helsinki as revised in 2000.

The

Results

A total of 49 subjects, 30 males and 19 females with a mean age of 68.33 years (SD 8.84) and with type 2 diabetes mellitus were included in the study. The mean duration of diabetes was 15.6 years (SD 12.0) and blood glucose was controlled mainly by hypoglycemic drugs and insulin. Mean weight for study sample was 81.5 kg (SD 17.2) and mean height was 159.5 cm (SD 9.2). The prevalence of peripheral sensory neuropathy was 20% (n = 10) in the left foot and 18% (n = 9) in the right foot. Based on

Discussion

This study highlights the limitations of ABPI in isolation in peripheral arterial assessment and diagnosis in people with diabetes mellitus. This study compared the incidence of peripheral arterial disease (PAD) diagnosis using ankle-brachial index and printed arterial waveforms in subjects with type 2 diabetes mellitus in a Maltese cohort seen in a hospital care setting.

As ABPI values below 0.9 are clearly indicative of PAD both in subjects with and without diabetes according to the Eurodiale

Conflict of interest

The authors report no conflict of interest.

Acknowledgments

The authors would like to thank all participants who consented to participate in this study.

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