Impact of radiographic vertebral fractures on inpatient healthcare utilization in older women.

Background: Vertebral fractures (VFx) are the most common osteoporotic fracture and are associated with higher risk of impaired function, additional fractures and death. The purpose of this analysis was to test the hypotheses that VFx are also associated with greater inpatient healthcare utilization.

Methods: We studied 4709 Caucasian women enrolled in the Study of Osteoporotic Fractures (SOF) and merged SOF cohort data with Medicare claims or Kaiser encounter data. To be included in this analysis, women had to be enrolled in Medicare Fee for Service or Kaiser as of 1/1/1991 and have radiographic information on VFx status at SOF Visit 3 (1991-92). VFx status was assessed using quantitative morphometry on lateral thoracic and lumbar spine radiographs. Prevalent VFx were defined as any height ratio>3 standard deviations below normal. Women were considered to have a clinical VFx if they reported a new diagnosis of VFx and a clinical radiographic report that confirmed that a VFx was present. Any hospitalization and the number of annualized days of hospitalization were identified through inpatient claims or encounter data. Specific hospitalizations for 5 major common reasons for hospitalizations were also examined.

Results: Over 5-years, 2632 (55.9%) women were hospitalized. In multivariate adjusted models, women with a prevalent radiographic VFx were 21% (95% CI, 2-44%) more likely to be hospitalized for any reason. This association was independent of a number of risk factors including smoking. The annualized rate of inpatient day was, however, similar, 1.67 and 1.48 among women with and without a VFx, respectively, p=0.49. Women with an incident clinical VFx were more likely to be hospitalized including women without evidence of a prevalent radiographic VFx (odds ratio (OR)=5.33; 95% confidence interval (CI)=1.81-15.71) and women with a prevalent radiographic VFx (OR=2.13; 95% CI, 1.05-4.33). Women with a VFx were more likely to be hospitalized specifically for hip fracture or chronic obstructive pulmonary disease (COPD) but not stroke, myocardial infarction or congestive heart failure. The association with COPD was attenuated to non-significance after adjusting for smoking.

Conclusion: Our results extend the potential public health impact of radiographic and clinical VFx to include an increased risk of any hospitalization.