Peak expiratory flow, walking speed and survival in older adults: An 18-year longitudinal population-based study

Peak expiratory flow (PEF) and walking speed (WS) have been proposed as indicators of robustness and are independent predictors of health-related outcomes. We aimed to investigate how the co-occurrence of respiratory and physical impairments changes as a function of age, and to quantify the association of the combination of low PEF and slow WS on survival in older people.

This prospective study analyzes data from 2656 community-dwelling participants (age ≥ 60 years) from the SNAC-K study. At baseline, we assessed: (1) sociodemographic, lifestyle and medical data; (2) respiratory function, estimated through PEF and expressed as standardized residual (SR) percentile; and (3) WS at usual pace, categorized as no (>1.2 m/s), mild (0.8-1.2 m/s) and moderate-to-severe (<0.8 m/s) walking impairment. Participants' vital status over an 18-year follow-up was derived from registers. The association of different combinations of PEF and WS on median survival time was estimated through Laplace regression adjusted for potential confounders.

Respiratory and walking impairments co-occurred more frequently with increasing age. Among individuals with PEF SR-percentiles < 10th, the percentage of moderate-to-severe walking impairment was 12.1% in sexagenarians, 35.7% in septuagenarians, and 75-80% in the oldest old. The greatest reduction in median survival time (-5.4 [95%CI: -6.4; -4.4] years, p < 0.001) was observed among people with combined respiratory and moderate-to-severe walking impairments, compared with those with no dysfunctions, who had a median survival time of 17.4 (95%CI: 17.0; 17.8) years.

Impaired PEF and WS co-occur more frequently with advancing age, and their co-occurrence is associated with shorter survival.