(sh:etiologia OR (ti:(risk* OR causa OR causas OR etiolog* OR causalidad* OR causality OR causes OR pathogenesis OR patogenes*) OR mh:risk* OR mh:"cohort studies") OR ti:(relativ* AND (risk* OR risco OR riesgo)) OR "relative risk" OR "risco relativo" OR ti:(cohort stud*) OR ti:(estud* coorte*))