## Bayesian classification of falls risk

## Abstract

Background. Prior research in falls risk prediction often relies on qualitative and/or clinical methods. There are two challenges with these methods. First, qualitative methods typically use falls history to determine falls risk. Second, clinical methods do not quantify the uncertainty in the classification decision. In this paper, we propose using Bayesian classification to predict falls risk using vectors of gait variables shown to contribute to falls risk. Research Questions: (1) Using a vector of risk ratios for specific gait variables shown to contribute to falls risk, how can older adults be classified as low or high falls risk? and (2) how can the uncertainty in the classifier decision be quantified when using a vector of gait variables? Methods. Using a pressure sensitive walkway, biomechanical measurements of gait were collected from 854 adults over the age of 65. In our method, we first determine low and high falls risk labels for vectors of risk ratios using the k-means algorithm. Next, the posterior probability of low or high falls risk class membership is obtained from a two component Gaussian mixture model (GMM) of gait vectors, which enables risk assessment directly from the underlying biomechanics. We classify the gait vectors using a thresholdmore »

- Authors:

- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); New Mexico State Univ., Las Cruces, NM (United States). Klipsch School of Electrical and Computer Engineering
- New Mexico State Univ., Las Cruces, NM (United States). Klipsch School of Electrical and Computer Engineering
- New Mexico State Univ., Las Cruces, NM (United States). Dept. of Kinesiology and Dance

- Publication Date:

- Research Org.:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 1483982

- Report Number(s):
- SAND-2018-11631J

Journal ID: ISSN 0966-6362; 670075

- Grant/Contract Number:
- AC04-94AL85000

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Gait & Posture

- Additional Journal Information:
- Journal Volume: 67; Journal Issue: C; Journal ID: ISSN 0966-6362

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 97 MATHEMATICS AND COMPUTING; 59 BASIC BIOLOGICAL SCIENCES

### Citation Formats

```
Martinez, Matthew, De Leon, Phillip L., and Keeley, David. Bayesian classification of falls risk. United States: N. p., 2018.
Web. doi:10.1016/j.gaitpost.2018.09.028.
```

```
Martinez, Matthew, De Leon, Phillip L., & Keeley, David. Bayesian classification of falls risk. United States. doi:10.1016/j.gaitpost.2018.09.028.
```

```
Martinez, Matthew, De Leon, Phillip L., and Keeley, David. Mon .
"Bayesian classification of falls risk". United States. doi:10.1016/j.gaitpost.2018.09.028. https://www.osti.gov/servlets/purl/1483982.
```

```
@article{osti_1483982,
```

title = {Bayesian classification of falls risk},

author = {Martinez, Matthew and De Leon, Phillip L. and Keeley, David},

abstractNote = {Background. Prior research in falls risk prediction often relies on qualitative and/or clinical methods. There are two challenges with these methods. First, qualitative methods typically use falls history to determine falls risk. Second, clinical methods do not quantify the uncertainty in the classification decision. In this paper, we propose using Bayesian classification to predict falls risk using vectors of gait variables shown to contribute to falls risk. Research Questions: (1) Using a vector of risk ratios for specific gait variables shown to contribute to falls risk, how can older adults be classified as low or high falls risk? and (2) how can the uncertainty in the classifier decision be quantified when using a vector of gait variables? Methods. Using a pressure sensitive walkway, biomechanical measurements of gait were collected from 854 adults over the age of 65. In our method, we first determine low and high falls risk labels for vectors of risk ratios using the k-means algorithm. Next, the posterior probability of low or high falls risk class membership is obtained from a two component Gaussian mixture model (GMM) of gait vectors, which enables risk assessment directly from the underlying biomechanics. We classify the gait vectors using a threshold based on Youden's J statistic. Results. Through a Monte Carlo simulation and an analysis of the receiver operating characteristic (ROC), we demonstrate that our Bayesian classifier, when compared to the k-means falls risk labels, achieves an accuracy greater than 96% at predicting low or high falls risk. Significance. Our analysis indicates that our approach based on a Bayesian framework and an individual's underlying biomechanics can predict falls risk while quantifying uncertainty in the classification decision.},

doi = {10.1016/j.gaitpost.2018.09.028},

journal = {Gait & Posture},

number = C,

volume = 67,

place = {United States},

year = {2018},

month = {10}

}