FRAILSURVEY—an mHealth App for Self-Assessment of Frailty Based on the Portuguese Version of the Groningen Frailty Indicator: Validation and Reliability Study

Luis Midao   ^{1, 2, 3} , PhD ;   Mafalda Duarte   ^{4, 5} , Prof Dr ;   Rute Sampaio   ⁶ , Prof Dr ;   Marta Almada   ^{1, 2} , PhD ;   Cláudia Camila Dias   ^{7, 8} , Prof Dr ;   Constança Paúl   ^{3, 4} , Prof Dr ;   Elísio Costa   ^{1, 2} , Prof Dr

¹ RISE-Health, Biochemistry Lab, Faculty of Pharmacy, University of Porto, Porto, Portugal

² Porto4Ageing—Competences Centre on Active and Healthy Ageing, Faculty of Pharmacy, University of Porto, Porto, Portugal

³ ICBAS—School of Medicine and Biomedical Sciences, University of Porto, Porto, Portugal

⁴ RISE-Health, Department of Behavioural Sciences, School of Medicine and Biomedical Sciences, University of Porto, Porto, Portugal

⁵ ISAVE—Superior Institute of Health, Amares, Braga, Portugal

⁶ RISE-Health, Department of Biomedicine, Faculty of Medicine of the University of Porto, Porto, Portugal

⁷ Knowledge Management Unit, Faculty of Medicine of the University of Porto (FMUP), Porto, Portugal

⁸ CINTESIS@RISE, Department of Community Medicine, Information and Health Decision Sciences (MEDCIDS), Faculty of Medicine of the University of Porto (FMUP), Porto, Portugal