David Klein

Background/Objective: Peripheral arterial disease (PAD) is a widespread but underdiagnosed manifestation of systemic atherosclerosis, associated with high morbidity and mortality. Traditional diagnostic methods such as the ankle-brachial index (ABI) have limited sensitivity in certain populations, highlighting the need for reliable blood-based biomarkers. Fatty Acid Binding Protein 3 (FABP3) has emerged as a robust biomarker with diagnostic utility in PAD. To evaluate the diagnostic performance of FABP3 when used in combination with traditional clinical risk factors for PAD in patients presenting to vascular surgery clinics. Methods: A retrospective analysis was conducted on 657 patients presenting to ambulatory vascular surgery clinics at St. Michael’s Hospital. Two logistic regression models were compared: (1) Model A: Included standard clinical risk factors (calf pain, age, smoking, diabetes, hypertension, hypercholesterolemia, coronary artery disease, and signs of chronic limb-threatening ischemia); and (2) Model B: Included the same factors as Model A, plus FABP3 levels. Diagnostic metrics including area under the curve (AUC), sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were assessed. Results: Among 657 patients, 423 had PAD and 234 did not. Model B (FABP3-integrated model) outperformed Model A, with a higher AUC (0.86 vs. 0.82), sensitivity (96% vs. 81%), specificity (84% vs. 67%), PPV (92% vs. 81%), NPV (94% vs. 65%), and diagnostic accuracy (93% vs. 76%). FABP3 also improved detection in asymptomatic PAD patients (84% detected vs. 0%). Conclusions: Integrating FABP3 with standard clinical risk factors significantly improves PAD diagnosis, especially in asymptomatic and borderline cases. These findings support the potential role of FABP3 in routine PAD screening, warranting further prospective studies for validation.

Introduction: The COVID-19 pandemic focused attention on the importance of vaccine security to national security. Demand for vaccines far exceeded supply when the first COVID-19 vaccines were released. Growing data suggest a non-perfect correlation among vaccine development, production, purchases, deliveries and vaccination rates. As such, the best approach to strengthening vaccine security remains unclear. In this study, we use an operations research/operations management framework to characterise the relationship between vaccine security and key supply chain predictor variables in high-income countries (HICs) and low-income and middle-income countries (LMICs). Methods: We performed a comparative analysis of vaccine security against eight supply chain variables in a purposive sample of five HICs and five LMICs during the early phase of the pandemic (31 March 2021 and 30 April 2021). All data were obtained from publicly available databases. We used descriptive statistics to characterise our data, basic statistics to compare data and scatter plots to visualise relationships. Results: Our data show greater vaccine security in HICs compared with LMICs (32.2% difference in April 2021; 95% CI 4.2% to 60.3%, p=0.03). We report a significant difference between HICs and LMICs in only two of the eight predictor variables studied. Interestingly, we observed large variation in vaccine security within HICs, with Canada, Israel and Japan being frequent outliers, and within LMICs, with India standing out. Conclusion: Our data suggest a stronger relationship between vaccine security and ‘downstream’ supply chain variables compared with ‘upstream’ variables. However, multiple outliers and the lack of an even stronger relationship suggests that there is no magic bullet for vaccine security. To boost vaccine resilience, countries must be well governed and strategically reinforce deficient aspects of their supply chains. Modest strength in multiple domains may be the best approach to counteracting the effect of an unfamiliar, novel pathogen.