Objectives: to compare the obtained and predicted peak expiratory flow (PEF) values between frail, pre-frail, and non-frail older adults; verify the association between PEF and FS; and establish cut-off points for PEF as determinants of frailty syndrome (FS).

Design: Cross-sectional study. LOCATION: Macapá, Amapá, Brazil.

Participants: Community-based study community-dwelling older people.

Methods: PEF was evaluated using a peak-flow meter and FS was evaluated using Fried's frailty phenotype. The statistical analyses performed included a multinomial logistic regression model and Receiver Operating Characteristic (ROC) curves to establish cut-off points for discriminating FS.

Results: 409 older adults with a mean age of 70.09±7.22 years were evaluated; of these, 58.7% were pre-frail, and 12.7% were frail. PEF was lower in frail than in pre-frail participants, and lower in pre-frail than in non-frail. Frail and pre-frail older adults obtained lower PEF values than predicted. PEF (% Predicted) was inversely associated with frailty and pre-frailty even after adjustment. Cut-off points were established to discriminate the presence of frailty in older men (PEF≤350L/min; AUC=0.669; sensitivity=76.92%; specificity=52%) and women (PEF≤220L/min; AUC=0.597; sensitivity=71.79%; specificity=46.98%).

Conclusions: Frail and pre-frail older adults presented significantly lower PEF than non-frail participants, and these values were lower than predicted. PEF was inversely associated with frailty and pre-frailty. PEF cut-off points can be used as a complementary method to indicate frailty in community-dwelling older adults.