A Descriptive Preanalytical Survey of Procedures Followed for the Screening of Glucose Dysregulation in Thalassemia Centers: Implications for Clinical Practice and Call for Harmonization.

Background: Over the last few decades, screening for dysglycemia in transfusion-dependent β-thalassemia patients (β-TDT) using an oral glucose tolerance test (OGTT) with fasting (FPG) and 2-hour plasma glucose (2h-PG) samples was recommended at 10, 12, 14, and 16 years, and annually thereafter. The precise measurement of PG levels is the mainstay for accurate diagnosis of dysglycemia and for limiting the risk of false-positive (i.e., overdiagnosis) and false-negative (i.e., underdiagnosis), especially in patients with PG values near the recommended cutoff values. Research objective: The primary objective of the survey was to describe the procedures of the preanalytical phase of screening for dysglycemia, using data from actual clinical practice at Centers caring for β-TDT patients. The collected data were compared to the international recommendations of the American Diabetes Association and the World Health Organization. Methods: This observational study was based primarily on an online questionnaire. All members of the International Network of Clinicians for Endocrinopathies in Thalassemia and Adolescent Medicine (ICET-A) were officially invited to participate. The questionnaire consisted of 6 sections and 22 questions, with single-, multiple-choice, and open-ended descriptive answer options. Results: 14 out of 18 invited Centers [Bulgaria, Cyprus, Greece, Iran (2), Italy (2), Oman, Qatar, Sri Lanka, Türkiye (3) and United Kingdom] accepted and completed the survey with a response rate of77.7 % The total number of β-TDT patients followed in the participating Centers was 3,372 with 2,932 (86.9 %)over the age of 10 years. A total of 549 patients were followed for thalassemia-related diabetes mellitus (Th-RDM). Furthermore, the survey across the 10 countries showed variable adherence to and deviations from current international guidelines. The lowest adherence rate was associated with the information and instructions given to patients prior to the OGTT and with how the blood samples were stored from collection to centrifugation and analysis. Differences in these factors may lead to unintended variations in the prevalence and severity of hyperglycemia, with important implications for clinical practice. To improve the quality of the pre-analytical phase across participating centers, the Standards for Reporting of Diagnostic Accuracy (STARD) statement was implemented. Conclusions: Based on the STARD statement, the pre-analytical blood sampling procedures for OGTT screening in thalassemia Centers require revision and standardization. To minimize preanalytical errors, a precise diagnostic approach, coupled with closer patient follow-up, is needed to reduce the risk of glucose measurement errors.