Role of physical performance measures for identifying functional disability among Chinese older adults: Data from the China Health and Retirement Longitudinal Study

RESEARCH ARTICLE Role of physical performance measures for identifying functional disability among Chinese older adults: Data from the China Health and Retirement Longitudinal Study Li Zhang1, Linwen Guo1, Huitao Wu2, Xiaowen Gong3, Junqi Lv1, Yanfang Yang ID1* a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 1 West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China, 2 Medical Big Data Center, People’s Liberation Army General Hospital, Beijing, China, 3 Epidemiology and Biostatistics Institute, Tianjin Medical University, Tianjin, China * Abstract OPEN ACCESS Citation: Zhang L, Guo L, Wu H, Gong X, Lv J, Yang Y (2019) Role of physical performance measures for identifying functional disability among Chinese older adults: Data from the China Health and Retirement Longitudinal Study. PLoS ONE 14(4): e0215693. https://doi.org/10.1371/ journal.pone.0215693 Editor: Bruno Pereira Nunes, Universidade Federal de Pelotas, BRAZIL Received: January 21, 2019 Accepted: April 5, 2019 Published: April 18, 2019 Copyright: © 2019 Zhang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: The data underlying the results presented in the study are from the China Health and Retirement Longitudinal Study, an open database on geriatrics (contact via http:// charls.pku.edu.cn/en/page/data/2011-charlswave1). Other researchers could register accounts to access these datasets. We did not have any special access privileges that others would not have. On this Webpage, the relevant questionnaires, codebook, and users’ guide are presented in the Documentation Related To Data Background Functional disability is a common health burden in older adults and follows a hierarchical pattern. Physical performance measures are useful for the objective estimation of functional disability. This study primarily aimed to compare the validity of handgrip strength and gait speed, alone and in combination, for recognizing the functional disability among Chinese older adults. This study also aimed to stratify the functional disability according to the criterion-referenced values of handgrip strength and gait speed. Methods We selected 6127 respondents from the 2011 wave of the China Health and Retirement Longitudinal Study. Here, we defined functional disability as needing any help in any items of activities of daily living (ADL) and instrumental activities of daily living (IADL). To assess the validity of physical performance measures alone and in combination for the recognition of functional disability, we conducted the receiver operating characteristic analysis. Results Compared with handgrip strength, the gait speed could better discriminate ADL disability and showed a satisfactory discriminant validity (area under the curve � 0.7) in men. However, this finding was not found in the recognition of IADL disability. When combining these two measures, the parallel test showed a high sensitivity with a poor specificity, whereas the serial test showed a perfect specificity with a poor sensitivity. Conclusion We developed the hierarchical cut-off values of handgrip strength and gait speed for identifying and stratifying the functional disability among Chinese adults over 60 years old. The speed test was superior to handgrip strength in identifying ADL disability. The parallel tests PLOS ONE | https://doi.org/10.1371/journal.pone.0215693 April 18, 2019 1 / 13 Handgrip strength and gait speed for identifying functional disability Using part. The relevant datasets are presented in Database Download part. In our study, we used the following three datasets: Demographic Background, Health Status and Functioning, and Non-blood Biomarkers (Biomarkers) datasets. These three datasets and the codebook are also within the manuscript and its Supporting Information files. Funding: The authors received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist. of those with high sensitivity perhaps could help identify the functional disability. Further work on cost-utility analysis is warranted. Introduction Functional disability, defined as a dependency in activities of daily living (ADL) and/or instrumental activities of daily living (IADL), is a significant and profound health outcome for older adults [1–4]. Functional disability is associated with future falls, cognitive decline, hospitalization, and mortality [5]. IADL are related to functioning independently in a given environment, whereas ADL are essential for self-care in routine activities [4–6]. In most older adults, functional disability presents a hierarchical pattern. They first encounter difficulty in performing IADL, followed by ADL [7–8]. ADL disability represents a relative severity stage in the disablement process. Functional disability can indicate the intrinsic capacity of older adults [9]. Many individuals experience periods of high and stable capacity, declining capacity (they may encounter IADL disability), and a significant loss of capacity (they may experience ADL disability). Interventions may have to be tailored depending on the presence and stage of intrinsic capacity. Therefore, stratifying older people according to the stage of intrinsic capacity trajectory (or functional disability) would likely facilitate the intervention programs to optimize the intrinsic capacity trajectory and achieve the goal of healthy aging. Thus, a valid, simple, and reliable tool for identifying high-risk disability population is critical, particularly in a health care program. The most widely used measuring instruments for functional disability are ADL and IADL, which are self-reported measuring tools without biometric measures. Furthermore, the physical performance measures are key factors to obtain the objective estimates of the older adults’ functional disability [3]. This importance is mainly due to the large evidence that physical performance measures are more rapid, portable, and less influenced by cultural and educational backgrounds, compared with self-report measures [10, 11, 12]. According to substantial evidence, handgrip strength and gait speed are the “vital signs” of functional disability in the general older population [13–16]. However, their abilities to identify functional disability are seldom examined and compared; these abilities may be highly beneficial to interventions. Meng-Chih Lee et al. reported the cut-off values of handgrip strength and gait speed to best discriminate the IADL disability of 2420 community-dwelling older adults in Taiwan [7]. Wen-Ni Wennie Huang et al. suggested that gait speed and handgrip strength could identify the onset of basic ADL disability over an 18-month period in older a (...truncated)