Exploring risk factors related to low calf circumference older adults with multimorbidity: From individual-centered perspective (Preprint)

BACKGROUND As the global population continues to age, the prevalence of sarcopenia is gradually increasing, and the loss of skeletal muscle mass is one of the manifestations of sarcopenia. Low calf circumference is often used as a predictor of poor skeletal muscle mass or sarcopenia. The older adults usually have a combination of multiple chronic diseases. There is a lack of evidence to explore the risk factors for low calf circumference with multimorbidity in Chinese community-dwelling older adults. OBJECTIVE This study aimed to explore the risk factors and potential categories in low calf circumference with multimorbidity older adult patients from an individual-centered perspective. METHODS We selected 15,874 participants from the Chinese Longitudinal Healthy Longevity Survey in 2018 and screened for low calf circumference older adult patients. The "individual-centered" Latent class analysis to classify potential multimorbidity groups. Applying elastic net to screen the reliable risk variables, multiple logistic regression was used to explore the risk factors in low calf circumference with multimorbidity. RESULTS A collection of 7956 older individuals was eligible for the research, with age over 90 years accounting for 49.77%, the prevalence of low calf circumference occurred in 66.68%, 27.22% with multimorbidity in low calf circumference. Between 65 and 89 years of age, the prevalence of multimorbidity increased with age. However, the majority of older adults are in reasonably good health after the age of 90. Five multimorbidity groups were identified by latent class analysis: multisystem morbidity diseases (3.60%), arthritis-rheumatism or rheumatoid diseases (18.47%), diabetes-hypertension diseases (15.23%), respiratory-heart diseases (16.02%), and cardiovascular diseases (46.68%). Through 12 variables screened by elastic net, multiple logistic regression showed different significant impaction to multimorbidity groups, including demographic background, behavioural characteristics, and physical and mental health factors. In particular, older patients who self-report poor health grading and live in urban areas need more attention. CONCLUSIONS Our results revealed that low calf circumference is a common phenomenon among older adults in the community-dwelling older adults, and combined multimorbidity is also a large group. In the low calf circumference older adult population, the proportion of multimorbidity does not simply increase with age. Multimorbidity in low calf circumference has been identified in five potential groups. Different groups have distinctive risk factors. Public health authorities should pay attention to the low calf circumference in older adult patients with multimorbidity, carrying out targeted interventions and enhancing health outcomes.