Author

Amy Win

Date

6-2014

Document Type

Thesis

Degree Name

M.P.H.

Department

Dept. of Public Health and Preventive Medicine

Institution

Oregon Health & Science University

Abstract

ABSTRACT Factors Associated with History of Hip Fracture in the Health and Retirement Study Background: Amongst all osteoporotic fractures, hip fractures are the most devastating because they are associated with considerable disability, loss of independence, diminished quality of life, and reduced survival. Epidemiological associations have been observed between hip fracture and demographic, lifestyle, and physical function variables. This cross-sectional study was designed to 1) examine prevalence of self-reported history of hip fracture and 2) evaluate factors associated with self-reported history of hip fracture in United States community-dwelling older adults. Methods: This is a cross-sectional analysis of Health and Retirement Study (HRS) participants who were 65 years or older in the 2004 wave who provided a response to “Have you fractured your hip since we talked (in the previous wave)?” The age-standardized prevalence of history of self-reported hip fracture was determined using 2000 US Census data as a reference population. Baseline characteristics of participants with a history of self-reported hip fracture and participants without a self-reported history of hip fracture were compared using the Student’s t-tests for continuous variables and the chi-square test for categorical variables. Logistic regression models were constructed to identify the crude and age-adjusted odds ratios (ORs) of hip fracture. Multivariate models were built using manual backward selection. Variables included in the final models were gender, age, body mass index (BMI), index of Activities of Daily Living (ADLs), Nagi functional items, index of serious health conditions, education, alcohol consumption, and marital, smoking, and health status. An additional multivariable model included self-reported history of falls.

Results: There were 10,640 participants (4,534 men and 6,106 women), with a mean age of 75.4 years, included in analyses. At the 2004 baseline interview, 1.3% of participants (42 men and 142 women) reported a history of hip fracture in the previous two years. When participant characteristics were examined by hip fracture history, we found that those who reported a history of hip fracture were more likely to be female, 85 years or older, within the underweight and normal BMI ranges, to report a history of fall, have multiple chronic conditions, and report multiple functional limitations compared to those without a history of hip fracture. When all covariates were included in the multivariate model, history of a fall remained the factor most strongly associated with hip fracture (OR 6.35; 95% CI 3.89, 10.36). Women had 88% higher likelihood of having experienced a hip fracture than their male counterparts (OR 1.88; 95% CI 1.19, 2.95). Participants who were 85 years and older were twice as likely to have a history of hip fracture (OR 2.03; 95% CI 1.14, 3.62) than participants who were 65 to 75 years old. A reduced risk of reported hip fracture was observed in the higher BMI categories. Compared to their normal weight peers, overweight (OR 0.45; 95% CI 0.27, 0.77) and obese (OR 0.36; 95% CI 0.19, 0.70) participants were less likely to have experienced a hip fracture. Participants who had difficulty with 1-5 ADLs had a 73% higher likelihood of having experienced a hip fracture (OR 1.73; 95% CI 1.02, 2.93), while participants who had difficulty with 6 or more ADLs had a three-fold higher likelihood (OR 3.07; 95% CI 1.79, 5.26) of having experienced a hip fracture than participants with no difficulties with ADLs. When the history of a fall covariate was removed from the multivariate model, it strengthened the association between hip fracture history and gender, index of IADLs, Nagi functional items, and serious health conditions. Conclusions: This study found hip fracture history was associated with female gender, advanced age, history of a fall, chronic health conditions and diminished physical functioning (as measured by index of ADLs and Nagi functional limitations). From our results we suspect that chronic health conditions, Nagi functional limitations, and ADLs work as upstream mediators and may increase the likelihood of hip fracture through falls. As the mean lifespan of people increases and as more people reach advanced age, the numbers of hip fracture cases are likely to increase. Our results suggest that certain members of the population are at higher risk for hip fracture.

Identifier

doi:10.6083/M4H130QC

School

School of Medicine

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