Aged Male female male 167 Female 165 human 165 Humans 151 aged 151 article 137 adult 135 Middle Aged 127 Adult 105 priority journal 102 controlled study 97 major clinical study 64 middle aged 56 clinical article 46 Aged, 80 and over 43 Adolescent 41 Argentina 39 adolescent 35 Child 29 Animals 21 child 21 risk factor 20 human cell 19 Prospective Studies 18 Severity of Illness Index 18 clinical trial 18 Article 16