Dynamic statistical model for predicting the risk of death among older Chinese people, using longitudinal repeated measures of the frailty index: a prospective cohort study

Abstract

Background Frailty is a common characteristic of older people with the ageing process. We aimed to develop and validate a dynamic statistical prediction model to calculate the risk of death in people aged ≥65 years, using a longitudinal frailty index (FI). Methods One training dataset and three validation datasets from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) were used in our study. The training dataset and validation datasets 1 to 3 included data from 9,748, 7,459, 9,093 and 6,368 individuals, respectively. We used 35 health deficits to construct the FI and a longitudinal FI based on repeated measurement of FI at every wave of the CLHLS. A joint model was used to build a dynamic prediction model considering both baseline covariates and the longitudinal FI. Areas under time-dependent receiver operating characteristic curves (AUCs) and calibration curves were employed to assess the predictive performance of the model. Results A linear mixed-effects model used time, sex, residence (city, town, or rural), living alone, smoking and alcohol consumption to calculate a subject-specific longitudinal FI. The dynamic prediction model was built using the longitudinal FI, age, residence, sex and an FI–age interaction term. The AUCs ranged from 0.64 to 0.84, and both the AUCs and the calibration curves showed good predictive ability. Conclusions We developed a dynamic prediction model that was able to update predictions of the risk of death as updated measurements of FI became available. This model could be used to estimate the risk of death in individuals aged >65 years.

Frailty Changes Predict Mortality in 4 Longitudinal Studies of Aging

“…In this study, we used multiple, repeated FI measurements from 4 large cohort studies of community-dwelling older adults to predict mortality. Similar to 2 previous studies (8,9), we also found that the current frailty level predicts mortality risk. Different from previous work, we furthermore differentiated between baseline FI differences and FI change over time.…”

“…In our study, we have shown that the FI can be used to monitor frailty changes and how these are related to mortality on the population level. In addition, joint models also provide a potential means to utilize repeated frailty measurements-which are increasingly available based on routinely collected data in clinical practice (10,19)-to predict individual-level health outcomes dynamically (9). We thus suggest to assess dynamic frailty (4,5) repeatedly in patients to evaluate their respective mortality risk and to assist doctors in their prediction of patient's prognosis.…”

“…Recently, 2 studies (6,7) associated steeper latent FI trajectory types with higher mortality risk, one study (8) reported that an increase between baseline and follow-up FI was associated with increased mortality risk, and another study (9) used the current FI as a longitudinal, time-varying predictor of mortality. Although these are important first steps toward the assessment of the impact of FI changes on mortality, these studies are limited as they either rely on study-specific latent FI trajectory types that do not provide a single estimate of how FI changes affect mortality on average (6,7), integrate just one follow-up measurement (8), or focus exclusively on the current FI value (9). In conclusion, it is currently unclear to which extent changes in the FI predict mortality in addition to baseline FI differences, which is the goal of this study.…”

Frailty Risk Prediction Model among Older Adults: A Chinese Nation-Wide Cross-Sectional Study

“…For the CLHLS, the FI proved to be a stable and reliable measure of frailty [ 23 ]. In this study, we used nine dimensions to calculate the FI, including cognitive function, chronic illness, ability to perform activities of daily living, activities of daily living, bodily function, self-rated health, hearing ability, visual function, psychological status and other (including heart rhythm, interviewer-rated health status, number of serious illnesses suffered in the past two years) [ 24 ]. The FI is the ratio of the defect score to the total score.…”

Frailty trajectories in the oldest old: Is the level or the rate of change more predictive of mortality?

“…Most of these studies, however, rely on static, one-time assessments, although it has been shown that individuals' FI change over time [7][8][9][10]. A few studies [11][12][13][14][15][16][17] have assessed the relationship between frailty changes or trajectories and mortality, generally finding FI increases or steeper trajectories to be associated with a higher mortality risk. However, mixed results have been found with regard to the question whether FI change captures mortality risk better than and independently of the current (most recent) FI observation [13,17].…”