internal validity 7 controlled study 6 human 6 Article 5 adult 5 female 5 major clinical study 5 male 5 Female 4 Humans 4 Male 3 Middle Aged 3 aged 3 cohort analysis 3 middle aged 3 Adult 2 Aged 2 Aged, 80 and over 2 Internal validity 2 Reproducibility of Results 2 area under the curve 2 diagnostic test accuracy study 2 external validity 2 high risk patient 2 machine learning 2 predictive value 2 procedures 2 receiver operating characteristic 2 reproducibility 2 retrospective study 2