# Identification of factors predictive of contralateral secondary hip fractures in patients after initial hip fracture - A prospective observational study

## TL;DR

This study identifies risk factors for contralateral hip fractures after an initial hip fracture, which could help prevent future fractures.

## Contribution

The study identifies living alone and multiple vertebral fractures as novel predictors of secondary hip fractures.

## Key findings

- Living alone and three or more vertebral fractures were confirmed as independent risk factors for secondary hip fractures.
- Low grip strength and hypertension were also identified as significant univariate risk factors.
- Risk factors for secondary hip fractures differ from those for primary hip fractures.

## Abstract

Hip fractures are the most serious osteoporotic fractures, and patients often develop contralateral hip fractures. Various factors are reported as risks for secondary hip fracture, but risk analysis is not yet standardized. We conducted a longitudinal prospective observational study of 1395 hip fracture patients followed for 345.2 ± 189.3 (3–795) days to identify risk factors for secondary hip fracture. Of the initial 1395 patients, we followed 1223 cases, excluding those who already had a contralateral hip fracture at time of enrollment. Univariate analysis using the log-rank test and Cox regression analysis of 51 factors such as age, BMI and living alone in relation to secondary hip fracture showed that four factors, namely, living alone, low grip strength (<18 kg), three or more existing vertebral fractures and hypertension, were significant risks for secondary fracture. Multivariate Cox regression analysis using factors identified as significant risks for secondary fracture in univariate analysis confirmed that living alone and the presence of three or more existing vertebral fractures could be useful in predicting risk for secondary hip fracture. Our results may provide important knowledge to prevent contralateral secondary hip fractures in patients after the first fracture.

•Primary hip fracture cases were followed to identify risks for secondary hip fracture.•Survival analysis revealed two independent risk factors for secondary hip fracture.•Case comparison revealed three independent risk factors for secondary hip fracture.•Living alone was identified as a risk for secondary hip fracture by both analyses.•Risk factors differ between primary and contralateral secondary hip fractures.

Primary hip fracture cases were followed to identify risks for secondary hip fracture.

Survival analysis revealed two independent risk factors for secondary hip fracture.

Case comparison revealed three independent risk factors for secondary hip fracture.

Living alone was identified as a risk for secondary hip fracture by both analyses.

Risk factors differ between primary and contralateral secondary hip fractures.