Self-explaining. The prevalence of different risk factors might be different in different geographic areas.
Medical literature, at the best systematic reviews on mechanism of disease, risk factors, course and prognosis.
Identification of alternative (i. e. preventive) approaches
Burls et al. 2001, Busse et al. 2002, Liberati et al. 1973 Imaz-Iglesia et al. 1998, Kristensen et al. 2009