Activities of daily living decline is a predictor of lowered coughing ability and correlates with rehabilitative effect of tongue cleaning on coughing ability

Basic activities of daily living (ADL) is a critical indicator of independency in older adults. The purpose of this study is to evaluate impact of ADL decline on coughing ability, as determined by peak expiratory flow rate (PEFR), and to evaluate impact of ADL decline on the ability of tongue cleaning intervention to improve PEFR. Methods: Participants comprised 95 residents of 11 group homes and nursing homes in Kumamoto, Japan. Participants were randomly assigned to cohorts with or without tongue cleaning intervention. Coughing ability was evaluated by measuring PEFR before and after 2 weeks, 4 weeks, and 3 months of intervention. Basic ADL was assessed by Barthel index (BI). Mean BI score among the participants was 59.3 ± 24.2. PEFR in a cohort with ≤ 60 BI score (LB) (1.2, 0.2–4.7 L s⁻¹) was significantly lower than that in a cohort with ≥ 61 BI score (HB) (1.8, 0.5–6.5 L s^− 1; p < 0.001). Multiple regression analysis revealed that BI score significantly correlated with PEFR after adjustment for various confounders (p < 0.004). Although tongue cleaning intervention increased PEFR in both cohorts, BI score only correlated with the amount of change of PEFR in the intervention group (p = 0.048). Basic ADL decline closely correlated with lowered coughing ability, as assessed by PEFR. Additionally, the rehabilitative effect of tongue cleaning on coughing ability was affected by basic ADL in older adults.