ODP137 Achilles Tendon Size and Characteristics for Diagnosis of Familial Hypercholesterolemia Among Thai Patients

Abstract Background The presence of tendon xanthomas, defined as thickening or nodularities of tendons, is subjective and remains largely undetected in patients with familial hypercholesterolemia (FH) in clinical practice. This study aimed to determine Achilles tendon thickness cutoff values associated with the highest diagnostic accuracy for identifying FH among Thai patients. Methods 63 subjects with possible, probable or definite FH according to the Dutch Lipid Clinic Network criteria, 58 subjects with hypercholesterolemia not compatible with FH and 55 normolipidemia subjects were recruited. Achilles tendon thickness was measured on each side separately at the point of maximum thickness using Lange skinfold calipers, Slim Guide skinfold calipers, plain radiograph of lateral ankles and ultrasonography. Ultrasonographic characteristics of the tendons were also recorded. The diagnostic performance of the maximum Achilles tendon thickness (maximum value of either left or right Achilles tendon of each person) obtained by each method was determined by Receiver-Operating Characteristic curves and optimal cut-points determined by Youden's index. Spearman rank-order correlation coefficient assessed factors associated with Achilles tendon thickness. Results Of all subjects, the mean age was 47 (±13) years, and 45% were male. The study groups were comparable in baseline characteristics except for a higher LDL cholesterol burden, a longer duration of lipid lowering therapy and a higher percentage of subjects receiving high intensity statins and ezetimibe in the FH group. Both types of skinfold calipers demonstrated 61% accuracy for diagnosing FH. An anteroposterior (AP) diameter on plain radiographs ≥7.7 mm had an 80% accuracy with 75% sensitivity and 82% specificity, whereas ultrasonographic thickness ≥6.4 mm. showed a 76% accuracy with 46% sensitivity and 93% specificity. Tendon border irregularities, diffuse hypoechogenicity and calcification were reported in a higher percentage of patients with FH, compared with the other 2 groups. Factors showing a significant correlation with Achilles tendon thickness in the FH group were years since FH diagnosis, a higher Dutch Lipid Clinic Network score and a higher body mass index (BMI). In the overall cohort, factors showing a significant correlation were higher LDL cholesterol burden and higher BMI. Conclusion Achilles tendon thickness measured by calipers showed low accuracy for FH diagnosis. An AP diameter on plain radiographs demonstrated highest sensitivity, whereas ultrasonographic thickness and area of Achilles tendon showed high specificity. Tendon irregularities, diffuse hypoechogenicity and calcification might serve as supportive findings. Presentation: No date and time listed