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Browsing by Subject "Diagnostic Accuracy"

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    Understanding Lower Extremity Symptoms for Improved Detection of Peripheral Artery Disease: The PREDICT PAD Study
    (2021-08) Brown, Rebecca
    Background Of all the major manifestations of atherosclerosis, peripheral artery disease (PAD) is one of the most underdiagnosed and undertreated vascular diseases, due, in part, to the large number of individuals who experience atypical symptoms, yet our current screening tools are designed to detect those with classic symptoms. PAD causes functional decline and disability, low quality of life, and increased risk of all-cause mortality and cardiovascular death, therefore there is an immediate need to improve detection methods. Aims This dissertation is aimed to 1) Comprehensively describe the range of atypical symptom characteristics in individuals with PAD, how atypical symptoms are defined, and examine potential factors associated with atypical symptoms reported in the literature. 2) Identify characteristics that discriminate between PAD and non-PAD in a group of previously undiagnosed individuals with any type of lower extremity symptoms. 3) Measure the effects of exercise on symptom reporting and calf muscle ischemia and 4) elucidate the experience of individuals with undiagnosed PAD and explore differences in symptomatology in those with and without PAD. Methods Aim 1. A critical review of the published literature on symptom description in PAD was conducted with a particular focus on articles delineating classic or typical symptoms from atypical symptoms. Studies were analyzed based on methodological approach including a) questionnaire-based, b) clinician assessment, and c) qualitative interview. The definitions and associated conditions are discussed. Aim 2. One-time study visit was conducted to evaluate lower extremity symptoms at rest, during, and post exercise in adults 60 years and older with persistent lower extremity symptoms, not previously diagnosed with PAD (n = 25). Symptom assessment included validated questionnaires, a symptom adjective checklist, measurement of muscle tissue oxygenation, and an exploratory semi-structured interview. The visit concluded with a diagnostic vascular assessment using the ankle brachial index (ABI) test. Results were analyzed by naturally occurring groups based off the ABI (abnormal vs normal ABI). Aim 3. Symptoms were measured pre and post six-minute walk test to determine whether exercise elicits symptoms that more closely resemble classic PAD symptoms. Muscle tissue oxygen saturation was measured using near infrared spectroscopy to determine differences in recovery time post exercise between the PAD and non-PAD group. Aim 4. A qualitative content analysis of the audio-recorded semi-structured interviews was conducted to gain a deeper understanding of the differences between those with and without PAD and to understand the experience of individuals with undiagnosed PAD. Results Aim 1. Twenty-four articles were included in the review and was comprised of 8,169 unique individuals with PAD, with an average age of 68.0 years (42.3% female). The definition of atypical symptoms varied across the literature, as did the prevalence ranging from 7.9% - 50.3%. Atypical symptoms were more often associated with increased rates of comorbid diseases, coexisting conditions affecting ambulation, and a greater number of PAD risk factors. The majority of participants reported atypical symptoms and as well as interference with activities of daily living, physical function, and social and personal lives. Aim 2. Four questions were statistically significantly different between participants in the PAD group vs. the non-PAD group. Two of the four questions are contrary to the expected findings. The questions that best differentiated PAD from non-PAD were “Do your symptoms disappear while walking?”, “Do you have difficulty keeping up with your friends or family?”, “Do you have symptoms while sitting?”, “Where are your symptoms?”. Participants in the PAD group reported that their symptoms did not disappear while walking, they had difficulty keeping up with friends and family, had pain while sitting, and were less likely to experience calf or thigh pain. Aim 3. Exercise did not yield symptoms that more closely resembled classic PAD symptoms. Post exercise, the sensitivity and specificity of the validated screening questionnaires were either unchanged or worse. Participants in the PAD group took longer to recover based off return to normal muscle tissue oxygenation levels. Aim 4. The content analysis revealed eight concepts, two of which were unique to the PAD group. These were: Breath of Physical Findings and Confounding Factors, Coping Strategies, Impact on Activities of Daily Living, Determinants of Behavior, Communication Barriers, Symptoms Threaten, Credibility Feels at Risk (PAD only), and Unexplained Symptoms are Distressing (PAD only). Conclusion This dissertation examined discriminating characteristics of PAD in a sample of participants who were previously undiagnosed. Four screening questions may improve detection of PAD, however there are many communication barriers, atypical symptoms, and overlapping symptoms which continuously plague this approach to screening. Participants with undiagnosed PAD experienced discomfort, social limitations, and were distressed over their symptoms. The results emphasize the need to use definitions that serve to meet the needs of the patients who experience them. A broader definition of claudication beyond classic claudication is needed to improve access to vascular testing and enhance detection of PAD.