Screening for frailty in older adults using a postal questionnaire: rationale, methods, and instruments validation of the INTER-FRAIL study.

To develop and test a postal screening questionnaire to intercept frailty in older community-dwelling individuals.A questionnaire was developed on the basis of expert consensus and preliminarily tested against the occurrence of incident disability, in secondary analyses of previous epidemiological studies. The questionnaire was then mailed and its concurrent validity, defined from the association between its individual items and summary score and the presence of the Fried frailty phenotype (FFP), was subsequently evaluated cross-sectionally with in-person examination of initial participants.Community-based.Individuals aged 70 and older living in two communities near Florence, Italy.A home comprehensive geriatric assessment including the FFP was conducted in participants who screened positive for frailty and in a limited sample of negative responders.A 10-item questionnaire, developed based on expert consensus, was preliminarily tested on preexisting epidemiological data and showed an area under the receiver operating characteristic curve (AUC) of 0.716 versus incident disability. The questionnaire was then mailed to 15,774 subjects, whose response rate was 53.6\%. Of the first 1,037 participants included in the concurrent validation study, 833 (80.3\%) screened positive, and 380 (36.6\%) were frail on assessment. The ability of the questionnaire summary score to predict frailty was adequate, with an AUC of 0.695, a sensitivity of 71\%, and a specificity of 58\%.A simple questionnaire delivered by mail was able to identify FFP in the community. This would facilitate large-scale screening for frailty in older persons.