The Strong Heart Study (SHS) is a study of cardiovascular disease and its risk factors among American Indian men and women supported by the National Heart, Lung, and Blood Institute (NHLBI) since October 1, 1988 and is the largest epidemiologic study of American Indians ever undertaken. The SHS, which uses standardized methodology, is designed to estimate cardiovascular disease mortality and morbidity and the prevalence of known and suspected cardiovascular disease risk factors in American Indians and to assess the significance of these risk factors in a longitudinal analysis.
The study included 13 American Indian tribes and communities in three geographic areas: an area near Phoenix, Arizona, the southwestern area of Oklahoma, and western and central North and South Dakota. In its initial stages, the SHS included two components. The first was the clinical examination of 4,549 eligible tribal members. The second component is the morbidity and mortality (M&M) surveillance of these 4,549 participants. The SHS has completed three clinical examinations of the original Cohort (Phase I: 1989-1991; Phase II: 1993-1995; Phase III: 1998-1999, respectively).
Due to the importance of genetics in the occurrence of CVD, the SHS expanded into the genetic epidemiology area. In the Phase III study, in addition to the original Cohort examination, the study conducted a pilot family study. The family pilot study recruited approximately 30 families (10 per field center) which consisted of more than 900 family members. Due to the success of the pilot study, Phase IV was funded to conduct a full-scale family study to investigate the heritability of CVD and its risk factors and perform linkage analysis to localize genes that contribute to CVD risk. In Phase IV, an additional 18 to 25 extended families (a total of about 900 members at least 15 years of age) were recruited from each of the field centers from 2001-2003. This provides a total of 3,776 individuals from 94 families, of whom 825 are Phase III participants re-examined in Phase IV. Phase V completed the second exam on over 90% of the living family cohort and continued surveillance of the original cohort. Follow-up of genetic findings continues with localized DNA sequencing, fine mapping and candidate gene genotyping. Phase VI was completed in 2019 and included morbidity and mortality surveillance of over 85% of the living family cohort and continued surveillance of the original cohort. Morbidity and mortality surveillance included cardiovascular disease, cancer, liver disease, and inflammatory disease. Phase VII is currently underway and includes continued surveillance beginning February 2019 for a seven-year duration. Support for a basic follow-up examination of approximately 3,500 participants during the Phase VII contract cycle will be included. The SHS Phase VII exam will serve as a platform for in-depth ancillary studies that are funded outside of the SHS contracts. These ancillary studies will be operationally integrated into the main study, and can propose additional exam components.