Venous Thromboembolism Risk Assessment in Prolonged Fasting During Ramadan: The Global Ramadan Free Thrombosis Project.

Background Fasting during the month of Ramadan is practiced by over a billion Muslims worldwide. This religious observance, which involves complete abstention from food and fluids during daylight hours, may contribute to dehydration and increase the risk of venous thromboembolism (VTE), particularly in hot climates. Despite this theoretical concern, limited clinical evidence exists on the actual incidence and risk of VTE associated with prolonged fasting. This study aimed to assess the risk of VTE in fasting individuals during Ramadan using the Caprini risk assessment model and propose a prophylactic strategy tailored for the fasting population. Methodology A multicenter, observational study was conducted across several countries during the Ramadan period. Standard Caprini scores were calculated, and additional fasting-specific risk factors, including fasting duration, temperature exposure, physical activity, and hydration, were recorded. The presence of varicose veins and a history of thrombophilia were also evaluated. VTE events were tracked and analyzed during the fasting period. Results A proportion of participants developed VTE during the fasting period. Those who experienced thrombotic events had higher Caprini risk scores and a greater prevalence of contributing factors such as varicose veins, venous reflux, and thrombophilia. All events occurred during the fasting period and were not attributed to other medical conditions. Conclusions Ramadan fasting may unmask or exacerbate thrombotic risk, particularly in individuals with pre-existing venous disease or thrombophilia. Risk stratification using the Caprini score, supplemented with fasting-specific factors, can help identify at-risk individuals. Targeted preventive strategies, including patient education, fluid management, and medical prophylaxis for high-risk groups, should be considered to ensure safe fasting practices during Ramadan.