In‐Hospital Hip Fracture Mortality Trends in Older Adults: The National Hospital Discharge Survey, 1988–2007

Abstract

To the Editor: Older adults have a 5- to 8 times greater risk of all-cause mortality during the first 3 months after hip fracture, with almost half of the mortality risk during the first year attributed to in-hospital deaths.1, 2Although hip fracture rates have decreased in older adults in the United States since the mid-1990s,3 there is little information about nationwide trends in in-hospital hip fracture mortality in older adults. A recent hip fracture–related mortality study in Texas demonstrated that in-hospital hip fracture–related deaths decreased 1.8% per year, from 75.4% in 1990 to 60.1% in 2007.4 The aim of the current study was to examine nationwide trends in in-hospital hip fracture mortality in older adults between 1988 and 2007. The National Hospital Discharge Survey (NHDS) database was used to generate unbiased national estimates of hip fracture hospitalizations. Only general hospitals and hospitals with an average length of stay of fewer than 30 days for all patients are included in the survey.5 Hospitalizations for hip fractures as the primary diagnosis were defined according to International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes 820.xx to 820.9. The in-hospital case-fatality rate was calculated as the proportion of hospital deaths that occurred within 30 days of hip fracture hospitalization. Trends in in-hospital hip fracture mortality according to selected characteristics were examined across 5-year periods using the Cochrane-Armitage test. The Charlson Comorbidity Index (CCI) was used to evaluate trends in in-hospital hip fracture mortality according to comorbidities.6 For an estimated 5.3 million hip fracture hospitalizations in the United States between 1988 and 2007, in-hospital hip fracture mortality was 4.9% (95% confidence interval (CI) = 4.2–5.7) in men and 2.6% (95% CI = 2.3–2.9) in women. In individuals with hip fracture who died in the hospital, cardiac arrhythmia, congestive heart failure (CHF), acute myocardial infarction (MI), chronic obstructive pulmonary disease (COPD), and electrolyte disorders were the leading listed secondary diagnoses. In general, in-hospital hip fracture mortality was higher in men and increased gradually with advancing age and higher comorbidity scores. As shown in Table 1, in-hospital hip fracture mortality decreased significantly over time in men, those aged 85 and older, blacks, older adults hospitalized in the northeastern and southern regions of the country, and those with a CCI score of 2 or greater. In-hospital mortality in women remained steady over the study period. The results of this study indicate that in-hospital hip fracture mortality decreased in older adults in the United States between 1988 and 2007. The downward trend in in-hospital hip fracture mortality was predominantly attributed to a decrease in deaths of the oldest old, men, blacks, and those with higher CCI scores. The present findings are similar to those of a hip fracture–related mortality study in Texas reporting downward trends in the proportion of hip fracture deaths that occurred in the hospital, in men, and in those aged 85 and older between 1990 and 2007.4 Likewise, nationwide studies from France and England have described a decrease in in-hospital hip fracture mortality for both sexes between 2002 and 2008 and between 1998 and 2009, respectively.7, 8 Older age, male sex, and comorbidities are factors reported to be associated with greater risk of in-hospital hip fracture mortality, which are consistent with the present findings.9 The marked sex differences in mortality in individuals with hip fracture have been observed during the first weeks and persist for at least 2 years after the fracture event.10 Moreover, men with hip fracture seem to be prone to acute postoperative complications, which may increase the risk of mortality.10 A previous study also demonstrated that, in 3,981 individuals with hip fracture, the prevalence of postoperative pneumonia, ischemic heart disease, cardiac arrhythmias, and sepsis was significantly higher in men than in women.9 Several limitations must be mentioned in interpreting these results. First, in-hospital hip fracture mortality may be underestimated because the NHDS does not include federal, military, or Veteran Affairs hospitals. Second, the NHDS does not collect data about other reported risk factors associated with in-hospital hip fracture mortality such as delay in surgery, early mobilization, place of residence, and dependency in activities of daily living. Third, the NHDS staff did not clinically verify the discharge ICD-9-CM codes. Despite these limitations, the present study found nationwide temporal trends in in-hospital hip fracture mortality in older adults. The downward trend in in-hospital hip fracture mortality seen during the study period was predominantly attributed to better survival among the oldest old, men, and those with a high comorbidity burden. Conflict of Interest: The author reports no conflict of interest. Author Contribution: Carlos H. Orces is responsible for the entire letter. Sponsor's Role: None.