Whether a polyethylene terephthalate bottle cap can be opened could serve as a common indicator for locomotive syndrome, frailty and sarcopenia.

AIM: This study aimed to develop an easy-to-use assessment that can be carried out anywhere by investigating the association between the ability to open a polyethylene terephthalate (PET) bottle cap and locomotive syndrome (LS), frailty and sarcopenia, and the screening ability of this method.

METHODS

This cross-sectional study was carried out between July 2022 and February 2024, analyzing 341 community-dwelling Japanese older adults (mean age 80.0 ± 6.9 years). We used odds ratios (OR) and their 95% confidence intervals (CI) to assess the association between the ability to open a PET bottle cap and LS, frailty and sarcopenia, as well as the screening ability of this method. LS was evaluated using the stand-up and two-step tests and Geriatric Locomotive Function Scale-5; frailty was evaluated using the Japanese version of the Cardiovascular Health Study criteria; and sarcopenia was evaluated using grip strength, walking speed and skeletal muscle mass index.

RESULTS

After adjusting for age, sex and body mass index, the binary logistic regression analysis showed that the inability to open a PET bottle cap was associated with LS stages 2 and 3 (OR 2.72, 95% CI 1.46-5.07), frailty according to the Japanese version of the Cardiovascular Health Study criteria (OR 3.38, 95% CI 1.23-9.24) and sarcopenia (OR 3.61, 95% CI 1.67-7.79). The receiver operating characteristic curve analysis showed moderate screening ability for LS, frailty and sarcopenia, with a positive predictive value of 97.4% for LS, and 93.9% for pre-frailty and frailty.

CONCLUSIONS

Notably, the positive predictive value was high for LS, and pre-frailty/frailty using the PET bottle method. The PET bottle method is "simple" and requires just "one action," and it holds promise for practical social implementation as a comprehensive assessment of LS (stages 2 and 3), frailty and sarcopenia. Geriatr Gerontol Int 2025; 25: 905-910.