Identification of Target Body Composition Parameters by Dual-Energy X-Ray Absorptiometry, Bioelectrical Impedance, and Ultrasonography to Detect Older Adults With Frailty and Prefrailty Status Using a Mobile App in Primary Care Services: Descriptive Cross-Sectional Study

Beatriz Ortiz-Navarro   ^{1 *} , MD ;   José Losa-Reyna   ^{2, 3 *} , PhD ;   Veronica Mihaiescu-Ion   ^{4, 5 *} , PT, MSc ;   Jerónimo Garcia-Romero   ^{6 *} , MD, Prof Dr ;   Margarita Carrillo de Albornoz-Gil   ^{6 *} , MD, PhD ;   Alejandro Galán-Mercant   ^{4, 5 *} , PhD, PT, Prof Dr

¹ Public Andalusian Health System, Málaga, Spain

² CIBER of Frailty and Healthy Aging, Madrid, Spain

³ Sports Science Research Centre, King Juan Carlos University, Madrid, Spain

⁴ Institute of Biomedicine of Cádiz, Cádiz, Spain

⁵ MOVE-IT Research Group, Department of Nursing and Physiotherapy, Faculty of Health Sciences, University of Cádiz, Cádiz, Spain

⁶ Área de Educación Física y Deportiva, Facultad de Medicina, Universidad de Málaga, Málaga, Spain

*all authors contributed equally