[Frail-VIG index: Convergent and discriminatory validity with respect to Short Physical Performance Battery in general population]

Abstract

Background and objective: Studies of frailty in primary health care (PHC) using frailty indexes are scarce. Frail-VIG index assesses the level of frailty through a multidimensional approach. The main objective was to investigate the convergent and discriminative validity of the frail-VIG index with respect to Short Physical Performance Battery (SPPB) in general population ≥ 70 years.

Population, materials and methods: Descriptive cross-sectional study. We included 416 non-institutionalized patients aged 70 years or over from two lists of general practitioners in a semi-urban healthcare center. Main variables were: frail-VIG index and SPPB.

Results: The value of the area under the ROC curve of frail-VIG index respect SPPB < 7 was 0.81 (95% CI: 0.76-0.86). Pearson's correlation coefficient was -0.59 (95% CI: -0.524 to -0.649). The mean of frail-VIG index in those classified as not frail by SPPB < 7 was 0.103 (95% CI: 0.094-0.112) and in the frail was 0.242 (95% CI: 0.215-0.269). We obtained significant differences in the mean and distribution of the SPPB according to the frail-VIG index categories. The frailty prevalence according to the frail-VIG index was 29.3% (95% CI: 25.2-33.9), initial 19%, intermediate 7.5% and advanced 2.9%. There were frailty people by frail-VIG index and not by SPPB < 7 the 10.4%; on the contrary the 9.6%, the mean of affected domains of frail-VIG index was 3.9 and 2.2, respectively.

Conclusions: The frail-VIG index presents adequate convergent and discriminative validity with respect to the SPPB that supports the use in PHC. There is a 20% of participants classified as frail in a discordant way, who presents a different profile.

Keywords: Atención primaria; Fragilidad; Fragility; Frailty index; Geriatric assessment; Primary health care; Psicometría; Psychometry; Valoración geriátrica; Índice de fragilidad.