Population reference equations for handheld peak expiratory flow in older U.S. adults.

Background: Peak expiratory flow (PEF) is a simple, inexpensive measure of respiratory effort and is a valuable predictor of health outcomes in older adults. Yet, there is a lack of epidemiological data validating PEF prediction equations among older adult populations, especially those ≥80 years. The National Health and Aging Trends Study (NHATS) is a large, nationally representative sample of U.S. adults ages ≥65 years that offers a unique opportunity to develop PEF population reference equations.

Methods: Using a healthy subsample from the NHATS 2011 cohort (N = 1740; 68.9 % female; mean [SD] age = 77.0 [7.9] years), sex-specific reference equations were generated for PEF, measured via a handheld flow meter, using height and age as predictors. Reference equations for both sexes were validated against the NHATS 2015 cohort by testing measured vs. predicted PEF values. Additionally, new reference equations were compared to spirometry PEF reference equations from the National Health and Nutrition Examination Survey (NHANES).

Results: After applying NHATS 2011 reference equations to the NHATS 2015 cohort, measured vs. predicted PEF values were not significantly different (Ps > 0.05). The NHANES equations tended to slightly overestimate handheld PEF measurements in the NHATS 2015 cohort by an average of 29.3 L/min and 10.1 L/min in males and females, respectively.

Conclusions: Results demonstrate the comparability of PEF reference equations from a handheld meter to spirometry reference equations in older adults. New reference equations can be applied to a traditionally undersampled population with an easily obtained and low-cost measure.