Modified Project Summary/Abstract Section PROJECT SUMMARY Overview. This K24 mid-career investigator award will support Dr. Mark Siedner to lead a mentoring program in patient-oriented research on detection and prevention of cardiovascular disease among people with HIV in sub-Saharan Africa. Candidate. Dr. Siedner is a physician scientist who serves as principal investigator (PI) or co-PI of four NIH R01-funded patient-oriented research (POR) projects on HIV and/or cardiovascular disease in sub-Saharan Africa, leading to over 220 peer-reviewed publications. He has also proven himself to be a highly successful mentor, with over two dozen past and current trainees, receipt of the Harvard Medical School Young Mentor Award, and evidenced by his role as co-director of an NIH T32 program in HIV clinical research at MGH (T32 AI007433), site PI of a global D43 clinical research training program on multimorbidity in Uganda (D43 TW011632), and program mentor in the Fogarty Clinical Research Fellowship (D43 T010543). Mentoring plan. This K24 award will allow Dr. Siedner to protect 25% of his time to be dedicated for training junior investigators in the US and sub-Saharan Africa in POR related to cardiovascular disease prevention among people with HIV. He will leverage an established pipeline of clinical research trainees identified through his leadership role on training grants and formalize a global cardiovascular disease research training program that focuses on career advancement and pairs US and African scientists with collaborative projects. Research Plan. Dr. Siedner will use the support provided by this award to pursue mid-career training in machine learning and clinical risk prediction. He will leverage the machine learning training and partnerships with experts in data science to comprehensively assess and validate individual and combinations of diagnostic screening modalities for cardiovascular disease among people with HIV in sub-Saharan Africa (Aims 1 and 2). This will be made possible with data from an NHLBI-funded R01 that includes CT angiography and extensive risk factor data in 600 individuals in Uganda. In a second project, he will use risk prediction techniques to derive and validate cardiovascular disease risk prediction scores among people with HIV in South Africa (Aim 3). This will be made possible by a Wellcome Trust-funded, population-based, longitudinal cohort study of over 18,000 people in South Africa who completed cardiovascular disease screening and are followed until hospitalization and death. The proposed work is directly in line with research priorities outlined in NIH NOT- 020-013 including prevention of HIV co-morbid conditions across the lifespan and research training of a multidisciplinary workforce. Moreover, Dr. Siedner’s longstanding commitment to training junior scientists makes him an excellent candidate for this award.