The role of socioeconomic status on hip fracture.
BACKGROUND
The impact of socioeconomic status-income and acculturation-on hip fracture is not well understood. We studied 116,919 fractures among 8,144,469 people in California. Greater income and English fluency predict lower fracture incidence. Lower income and immigrant populations are at increased risk for hip fracture and require intervention. Race/ethnicity is a major determinant of hip fracture risk. Although socioeconomic status (e.g., income and acculturation) is often associated with race/ethnicity, its impact on hip fracture incidence is less well understood.


METHODS
We carried out a retrospective, population-based, study of persons with hip fractures in California, 1996 to 2000, compared to census estimates by zip code. We performed Poisson regression analyses to calculate hip fracture incident rate ratios for gender, age, race/ethnicity, income, language (percent non-English speakers)-a proxy for acculturation-and living in rural areas.


RESULTS
During the 5-year period, 116,919 fractures occurred among 8,144,469 persons (2.87 fractures/1,000 persons per year). Higher income predicted lower hip fracture incidence. Persons in the highest decile of estimated income had an incident rate ratio (IRR) of 0.79 (95% confidence interval (CI) 0.77 to 0.82) compared with those in the lowest decile. Greater IRR of hip fracture was predicted for persons living in areas with a greater percent of non-English speakers (IRR 1.004, 95% CI 1.003 to 1.005).


CONCLUSIONS
Low income and language fluency are predictors of greater hip fracture incidence. Although much attention is given to the aging of the "baby boomers", low income and immigrant populations are at increased risk for hip fracture and require intervention.
Zingmond
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Division of General Internal Medicine and Health Services Research, Department of Medicine, The David Geffen School of Medicine at UCLA, 911 Broxton Plaza, Los Angeles, CA, 90095-1736, USA. dzingmond@mednet.ucla.edu
Soohoo
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Silverman
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D000069:Acculturation; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002140:California / Q000453:epidemiology; D004812:Epidemiologic Methods; D005260:Female; D006620:Hip Fractures / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019303:Multilingualism; D012959:Socioeconomic Factors