human Humans 402 female 311 male 294 adult 271 Article 241 Female 174 major clinical study 168 Male 161 controlled study 161 middle aged 132 article 126 Adult 116 aged 114 Middle Aged 101 retrospective study 95 United States 82 questionnaire 78 Aged 76 Retrospective Studies 75 cross-sectional study 68 cohort analysis 66 child 61 procedures 61 adolescent 59 young adult 58 economics 55 health care cost 53 Young Adult 52 organization and management 51