Abstract
Nursing home residents with a history of hip fractures or prior osteoporotic fractures were found to have an increased risk of another osteoporotic fracture over the ensuing two years when compared to nursing home residents with no fracture history.
Introduction
Because of the high prevalence of osteoporosis and fall risk factors in nursing residents, it is possible that the importance of previous fracture as a marker for subsequent fracture risk may be diminished. We tested whether a history of prior osteoporotic fractures would identify residents at increased risk for additional fractures after nursing home admission.
Methods
We identified all Medicare enrollees age 50 and older who were in a nursing home North Carolina in 2000 (n=30,655). We examined Medicare hospitalization claims to determine which enrollees had been hospitalized in the preceding 4 years for a hip fracture (n=7,257) or other fracture (n=663). We followed subjects from their nursing home entry until the end of 2002 using Medicare hospital claims to determine which subjects were hospitalized with a subsequent fracture (n=3,381).
Results
Among residents with no recent fracture history, 6.8% had a hospital claim for a subsequent fracture, while 15.1% of those with a prior non-hip fracture and 23.9% of subjects with a prior hip fracture sustained subsequent fractures. Multivariate proportional hazards models of time to fracture indicated that persons with prior hip fractures are at three times the risk (HR=2.99, 95% CI: 2.78, 3.21) and those hospitalized with other non-hip fractures are at 1.8 times the risk of subsequent fractures (HR=1.84, 95% CI: 1.50, 2.25).
Conclusion
Nursing home residents hospitalized with a prior osteoporotic fracture are at an increased risk of a fracture.
Keywords: hip fracture, nursing home residents, osteoporosis, osteoporotic fractures
Introduction
Hip fractures extract a heavy toll on older adults, especially nursing home residents [1–2] with annual incidence rates of 3–6% for hip fractures [3–5]. Residents of nursing homes with a hip fracture are 15 times more likely to be admitted to a hospital in the month after their fracture than NH residents who do not sustain a hip fracture [2]. Studies have evaluated risk factors for hip fractures in residents of long term care facilities; they include increasing age, female sex, falls, cognitive impairments, neurological disease, impaired mobility and urinary incontinence [3,4].
While osteoporotic fractures are a risk factor for subsequent osteoporotic fractures in community dwelling subjects [6], we are unaware of studies that have addressed the impact of previous fractures on subsequent fractures in nursing home residents. Because of the high prevalence of osteoporosis and fall risk factors in nursing home residents, it is possible that the importance of previous fracture as a marker for subsequent fracture risk may be diminished.
Upon admission to a Medicare or Medicaid funded-nursing home and at least every ninety days thereafter, each resident undergoes a comprehensive evaluation using the Minimum Data Set (MDS). The MDS contains the following information: demographics, functional status, some medical problems, selected medications and treatment programs. Work has shown that the MDS can be used to assess hip fractures and other osteoporotic fractures in residents of long term care facilities [3–5] We used the North Carolina MDS assessments of nursing home residents and Medicare hospital claims to identify residents at risk for subsequent fractures. We calculated the rates of fractures in Medicare enrollees who spent time as NH residents by prior fracture status. We identified demographic and medical characteristics associated with fracture after nursing home stay.
Methods
Study Population
This study uses data collected by the Carolinas Center for Medical Excellence, the North Carolina Quality Improvement Organization. The study was exempt from Institutional Review Board approval.
MDS assessments from North Carolina nursing homes were used to identify the potential patient population. All MDS assessments conducted during calendar year 2000 were selected (n= 251,799). If a resident had more than one assessment during the calendar year, the first assessment was selected to eliminate duplicates and retain a population of all residents who were in NC nursing homes for any period of time during the year (n=72,950). This population was linked with the Medicare Enrollment Database to identify North Carolina Medicare enrollees (n=31,165). The study population was restricted to enrollees age 50 and older (n=30,655). The study population of Medicare enrollees with a nursing home stay during 2000 represented 3.3% of NC Medicare enrollees in the year 2000.
Classification of prior fracture status and subsequent fractures
NC Medicare hospital claims were examined for a seven-year period (1996–2002) to identify hospitalizations with a hip or other fracture. Primary and secondary diagnosis codes from the hospital claims were used to identify hospitalizations claims for fractures (ICD-9 codes 820x or 733x for hip fractures and codes and 821x-829x for other osteoporotic fractures). All hip or osteoporotic fractures were included regardless of the potential cause of the fracture.
The nursing home assessment reference date was used as the index date. Fracture-related hospitalizations occurring prior to the nursing home admission were classified as “prior” fractures. Prior fracture status was analyzed using three categories: history of prior hip fracture; history of other fractures; and no recent (1996–2000) history of either type of fracture. Subjects with both hip and non-hip fractures were included in the prior hip fracture group.
Fractures after the nursing home admission were classified as “subsequent” fractures. Using the nursing home assessment reference date and the date of fracture, time to subsequent fracture (in days) was calculated. Enrollees who were fracture free were assigned the number of days of observation (either the number of days from nursing home admission until the end of the study window or the number of days from nursing home admission until death). Cumulative subsequent fracture rates were calculated from the date of nursing home assessment through the follow up period by prior fractures status.
Identification and definitions of characteristics of study population
Characteristics of the study population were obtained from the Medicare Enrollment Database (age, race, sex and date of death) and the MDS assessment (comorbidities, medication use, and history of falls and length of stay in the nursing home). Age was examined as both continuous and categorical formats. As a categorical variable, it was classified into four groups: age 50 – 64; age 65–74, age 75–84 and age 85 and older, with the younger age group serving as the referent for modeling. Race was dichotomized with Caucasian compared to all other races. Length of stay was examined in two categories: less than 90 days and 90 days or more, with the longer stay serving as the referent in models. Health conditions from the MDS were treated as dichotomous variables, either present or not. Two variables were available to capture fall history and each was dichotomous: fall history in the past 30 days (Yes/No) and fall history in the past 31–180 days (Yes/No). History of dizziness, fainting or unsteady gait were categorized as present or not. Medication use contained four categories: 1–2 medications; 3–5 medications, 6–9 medications and 10 or more. Use of five types of medications was also assessed with the MDS: anti-psychotic, anti-anxiety, anti-depressant, hypnotic and diuretic medications. Type of medication variables were all dichotomous (Yes/No).
Analytic Approach
Our primary goal was to characterize the effect of prior fracture history on subsequent fracture risk in a population of adults with nursing home stays. To avoid the potential to attribute increased risk to fracture history when it was due to some other condition, we sought to identify and control for other factors that had the potential to confound the association between prior fracture and subsequent fracture. For a factor to act as a confounder, it must be related to both the exposure of interest, in this case, prior fracture status, and the outcome of interest, subsequent fracture [7]. We conducted a series of analyses to assess associations between enrollee characteristics and prior fracture status and associations between those same characteristics and subsequent fracture. Statistical analyses were conducted in SAS, version 9.1 (SAS Institute, Cary NC, 2002) using chi-square and t-tests as appropriate to the variable classification. A significance level of 0.05 was used for statistical inferences. Statistical tests were adjusted for multiple comparisons using the multitest procedure in SAS. Cumulative fracture rates were calculated at 3 months, 6 months, 1 year and 2 years, using the nursing home assessment reference date as the start of the interval.
Cox proportional hazard regression was used to estimate the relative risk of fracture within two years of admission to nursing home associated with prior fracture status. The proportional hazard assumption for the Cox regression models was evaluated and the proportional hazard model was deemed appropriate.
Multivariate modeling was conducted to assess the association of prior fracture status controlling for other potential confounders. Two variables representing prior fracture risk (one for prior hip fracture and one for other type of fracture) were included in the models with those with no prior fracture serving as the referent. Age, race, sex and length of stay were included in all models as control variables. Additional potential confounder variables were tested for significance in the multivariate models if they were associated with the independent variable (prior fracture status) or outcome (fracture within two years of nursing home admission [7]. We began with a model containing all potential covariates and, using a backwards approach, dropped variables from nested models one-by-one using the −2 log likelihood test to assess fit of the reduced model [8]. Hazard ratios were computed by maximum likelihood techniques. Fracture free days were graphed using the life-test procedure in SAS, following all residents from date of entry into the nursing home until death, hospitalization for fracture, or end of the study window (12/31/2002).
Results
In 2000 there were 30,665 Medicare enrollees in North Carolina with a nursing home stay aged 50 years and older. Although the majority of enrollees had no recent history of fracture (Table 1), a substantial number (n=7,257) had prior hip fractures and a small number (n=663) had evidence of other fractures based on Medicare hospitalization claims. The prior hip fracture group was older than both the group with history of other fractures and those with no history of fracture (Table 1). Enrollees in both the prior hip fracture and other prior fracture groups were more likely to be Caucasian and female than enrollees with no recent history of fracture. A higher proportion of enrollees in both prior fracture groups were short stay (less than 90 days) residents compared to the group with no fracture history, and were more likely to have a history of a fall in the last 30 days. Two conditions recorded in the MDS were less common in both groups of enrollees who had previous fractures: dementia of the non-Alzheimer’s type and history of cerebrovascular disease.
Table 1.
Characteristics of Medicare Enrollees Admitted to North Carolina Nursing Home in 2000, by Prior Fracture Status (n=30,665)
| History of Prior Hip Fracture (n=7,257) | History of Prior Fracture, Other than Hip (n=663) | No History of Prior Fracture (n=22,745) | |||||
|---|---|---|---|---|---|---|---|
| Number | Percent | Number | Percent | Number | Percent | ||
| Age | Mean age (years) | 83.3‡ | -- | 78.8‡ | -- | 80.2 | -- |
| Race | Black | 565 | 7.8† | 107 | 16.1† | 5,086 | 22.4 |
| White | 6,646 | 91.6† | 552 | 83.3† | 17,442 | 76.7 | |
| Other | 46 | 0.6 | 4 | 0.6 | 217 | 0.9 | |
| Sex | Male | 1,205 | 16.6 | 132 | 19.9 | 8,332 | 36.6 |
| Female | 6,052 | 83.4† | 531 | 80.1† | 14,410 | 63.4 | |
| Nursing Home Length of Stay | Less than 90 days | 5,149 | 70.9† | 491 | 74.1† | 14,826 | 65.2 |
| 90 days or longer | 2,108 | 29.1† | 174 | 25.9 | 7.919 | 34.8 | |
| Health Conditions | Arthritis | 1,847 | 25.5† | 5,103 | 22.4 | 144 | 21.7 |
| Alzheimer’s | 746 | 10.3 | 38 | 5.7† | 2,437 | 10.7 | |
| Other Dementia | 1,574 | 21.7† | 109 | 16.4† | 5,481 | 24.1 | |
| CVA | 1,206 | 16.6† | 102 | 15.4† | 5,846 | 25.7 | |
| Hemiplegia | 345 | 4.7† | 45 | 6.8 | 2,184 | 9.6 | |
| MS | 11 | 0.2 | 5 | 0.8 | 68 | 0.3 | |
| Parkinson’s | 290 | 4.0 | 14 | 2.1 | 965 | 4.2 | |
| Seizure | 348 | 4.8† | 37 | 5.6 | 1,375 | 6.0 | |
| TIA | 270 | 3.7 | 18 | 2.7 | 726 | 3.2 | |
| Depression | 1,522 | 21.0 | 109 | 16.4 | 4,400 | 19.3 | |
| Diabetes | 1,420 | 19.6† | 226 | 34.1 | 6,978 | 30.7 | |
| Hypertension | 3,887 | 53.6 | 362 | 54.6 | 12,736 | 56.0 | |
| Asthma | 195 | 2.7 | 22 | 3.2 | 557 | 2.4 | |
| Emphysema | 1,365 | 18.8 | 88 | 13.3 | 4096 | 18.0 | |
| Fall History | Fall in last 30 days | 3,957 | 54.5† | 379 | 57.2† | 6393 | 28.1 |
| Fall in 31–180 days | 1,010 | 13.9† | 93 | 14.0 | 2,360 | 10.4 | |
| Other history | Dizziness | 178 | 2.4 | 15 | 2.3 | 622 | 2.7 |
| Fainting | 49 | 0.7 | 4 | 0.6 | 186 | 0.8 | |
| Unsteady gait | 3295 | 45.4† | 243 | 36.6 | 9364 | 41.2 | |
| Medication Use | 1–2 meds | 160 | 2.2† | 18 | 2.7 | 750 | 3.3 |
| 3–5 meds | 961 | 13.2† | 99 | 14.9 | 4,016 | 17.7 | |
| 6–9 meds | 2,738 | 37.7 | 252 | 38.0 | 8,864 | 39.0 | |
| 10 or more | 3,386 | 44.7† | 292 | 44.0 | 9032 | 39.7 | |
| Type Medications | Antipsychotic | 907 | 12.5† | 69 | 10.4 | 3,455 | 15.2 |
| Antianxiety | 1473 | 20.3 | 120 | 18.1 | 4119 | 18.1 | |
| Antidepressant | 2,272 | 31.3† | 192 | 29.0 | 6,419 | 28.2 | |
| Hypnotic | 762 | 10.5 | 68 | 10.3 | 2,153 | 9.5 | |
| Diuretic | 2,422 | 33.4 | 237 | 35.7 | 8089 | 35.6 | |
significantly different from no history of prior fracture, t-test p < 0.05
significantly different from no history of prior fracture, chi-square p < 0.05
Several conditions were noted as more prevalent in the group with prior hip fracture, but not the group other types of prior fractures, when compared to those with no fracture history: history of a fall in the past 31–180 days, unsteady gait, use of 10 or more medications and the use of antidepressant medications. Several health conditions were less prevalent in the hip fracture group: hemiplegia, history of seizure and diabetes.
Eleven percent (n=3,381) of enrollees suffered a subsequent fracture within two years (Table 2). Characteristics associated with increased fracture risk within two years were: older age, white race, female sex, nursing home stay of less than 90 days, arthritis, TIA, depression, emphysema. prior history of falls (both in 30 and 31–180 day time periods), unsteady gait, 10 or more medications and use of three specific medications: antianxiety, antidepressant and hypnotic medications. Medical characteristics associated with decreased risk of subsequent fracture were: non-Alzheimers’ dementia, CVA, hemiplegia, seizure, diabetes, and use of fewer medications.
Table 2.
Characteristics Associated with Fracture within 2 Years of Nursing Home Admission (n=30,665)
| Fracture within 2 years | |||
|---|---|---|---|
| Number | Percent* | ||
| Total | 3,381 | 11 | |
| Age | Mean age (years) | 82.5‡ | -- |
| Race | Black | 245 | 4.2† |
| White | 3,113 | 12.6† | |
| Other | 23 | 8.6 | |
| Sex | Male | 513 | 5.3 |
| Female | 2,868 | 13.7† | |
| Nursing Home Length of Stay | Less than 90 days | 2,477 | 12† |
| Health Conditions | Arthritis | 953 | 13.4† |
| Alzheimer’s | 333 | 10.3 | |
| Other Dementia | 700 | 9.8† | |
| CVA | 516 | 7.2† | |
| Hemiplegia | 135 | 5.2† | |
| MS | 4 | 4.8 | |
| Parkinson’s | 143 | 11.3 | |
| Seizure | 137 | 7.8† | |
| TIA | 137 | 13.5 | |
| Depression | 764 | 12.7† | |
| Diabetes | 701 | 8.1† | |
| Hypertension | 1,818 | 10.7 | |
| Asthma | 107 | 13.8 | |
| Emphysema | 706 | 12.7† | |
| Fall History | Fall in last 30 days | 1,593 | 14.8† |
| Fall in 31–180 days | 486 | 14† | |
| Other history | Dizziness | 93 | 11.4 |
| Fainting | 33 | 13.8 | |
| Unsteady gait | 1,706 | 13.2† | |
| Medication Use | 1–2 meds | 52 | 5.6† |
| 3–5 meds | 468 | 9.2† | |
| 6–9 meds | 1,228 | 10.4 | |
| 10 or more | 1,623 | 12.8† | |
| Type Medications | Antipsychotic | 432 | 9.7 |
| Antianxiety | 767 | 13.4† | |
| Antidepressant | 1,115 | 12.5† | |
| Hypnotic | 389 | 13† | |
| Diuretic | 1,156 | 10.8 | |
The percent represents the percent persons with the characteristic who had a fracture in the two year period. Percents greater than the 11% of fractures in the total study population indicate higher fracture rates among people with the characteristic. Percents less than 11% inidicate lower fracture rates among people with the characteristic.
significantly different from those with no fracture in 2 years, t-test p < 0.05
significantly different from those with no fracture in 2 years, chi-square p < 0.05
Fracture rates were highest among the group with history of prior hip fractures and lowest among those with no history of prior fracture (Table 3). Elevated fracture rates for the two groups with prior fracture were observed as early as 3 months and throughout the study window. The cumulative two-year fracture rates were: 23.9% for those with prior hip fracture, 15.1% for those with history of non-hip fracture, and 6.8% for those with no history of fracture.
Table 3.
Fracture Rates of NC Medicare Enrollees with Nursing Home Stay in 2000, by Prior Fracture Status
| History of Prior Hip Fracture (n=7,257) | History of Prior Fracture, Other than Hip (n=663) | No History of Prior Fracture (n=22,745) | |
|---|---|---|---|
| Timing of Fracture | Percent | Percent | Percent |
| 3 months from admission | 7.4 | 4.7 | 1.8 |
| 6 months from admission | 11.7 | 6.2 | 3.0 |
| 1 year from admission | 17.1 | 8.9 | 4.7 |
| 2 years from admission | 23.9 | 15.1 | 6.8 |
Note: all differences statistically significant, chi-square p < 0.05
The probability of remaining fracture free, as represented by the survival curves for fracture risk (Figure) was statistically significantly longer for those without prior history of fracture compared to those with history of prior hip or other fractures. The unadjusted hazard ratio for those with history of hip fractures was 3.88 (95% CI: 3.62, 4.15) compared to those with no prior history of fracture, and 2.11 (95% CI: 1.72, 2.58) for those with history of other type of fracture (Table 4). Although adjustment by age, race, sex and length of stay in nursing home reduced the estimated hazard associated with prior fracture, the risks of subsequent fracture remained significant: HR=3.08 (95% CI: 2.87, 3.31) and HR=1.84 (95% CI: 1.50, 2.25) for prior hip fracture and prior other fracture, respectively.
Figure.
Estimate of Time to Fracture for NC Medicare Enrollees Admitted to Nursing Home in 2000, by Prior Fracture Status
Table 4.
Relative risk of fracture within 2 years of nursing home admission among NC Medicare Enrollees
| Model | Strata | Hazard Ratio | 95% Confidence Intervals | |
|---|---|---|---|---|
| LCL | UCL | |||
| Crude | Prior hip fracture | 3.88 | 3.62 | 4.15 |
| Prior other fracture | 2.11 | 1.72 | 2.58 | |
| Adjusted for Age, Sex and Race | Prior hip fracture | 3.19 | 2.97 | 3.42 |
| Prior other fracture | 1.93 | 1.58 | 2.37 | |
| Age, Sex, Race and Nursing home LOS | Prior hip fracture | 3.08 | 2.87 | 3.31 |
| Prior other fracture | 1.84 | 1.50 | 2.25 | |
Results from the multivariate analyses showed significant increased risk of subsequent fracture within a two year follow up associated with prior fracture status even after adjustment for other patient conditions. In the final model (Table 5), persons with prior hip fractures were three times as likely as those with no fracture history to suffer another fracture in two years (HR=2.99, 95% CI: 2.78, 3.21) and those with prior non-hip fractures were almost twice as likely (HR=1.84, 95% CI: 1.50, 2.25). The final model also identified nine conditions that were important in predicting subsequent fracture risk. In addition to age, race, sex and length of stay in nursing home, which were retained in the final model as control variables, six health-related conditions from the MDS assessment were associated with increased risk of later fracture: arthritis (HR:1.08, 95% CI: 1.01, 1.17); depression (HR:1.13, 95% CI: 1.04, 1.23); emphysema (HR:1.36, 95% CI: 1.25, 1.48); fall in the past 31–180 days (HR:1.23, 95% CI: 1.12, 1.36); unsteady gait (HR:1.17, 95% CI: 1.10, 1.26); and use of antianxiety medication (HR:1.15, 95% CI: 1.06, 1.25). Three conditions from the MDS were associated with decreased risk of subsequent fractures: stroke, hemiplegia and diabetes.
Table 5.
Predictors of fracture within two years of nursing home admission among NC Medicare enrollees
| Characteristic Or Condition | Hazard Ratio | 95% Confidence Intervals | |
|---|---|---|---|
| LCL | UCL | ||
| No prior fracture | 1.0 | -- | -- |
| Prior hip fracture | 2.97 | 2.76 | 3.19 |
| Prior other fracture | 1.84 | 1.50 | 2.26 |
| Age 50 – 64 | 1.0 | -- | -- |
| Age 65–74 | 1.10 | 0.89 | 1.37 |
| Age 75–84 | 1.25 | 1.02 | 1.54 |
| Age 85 and older | 1.38 | 1.13 | 1.70 |
| Male | 1.0 | -- | -- |
| Female | 1.80 | 1.64 | 1.99 |
| Other race | 1.0 | -- | -- |
| Caucasian | 1.80 | 1.58 | 2.05 |
| LOS 90 days or longer | 1.0 | -- | -- |
| LOS less than 90 days | 1.56 | 1.44 | 1.69 |
| Arthritis | 1.08 | 1.01 | 1.17 |
| CVA | 0.86 | 0.77 | 0.95 |
| Hemiplegia | 0.73 | 0.61 | 0.89 |
| Depression | 1.13 | 1.04 | 1.23 |
| Diabetes | 0.87 | 0.81 | 0.96 |
| Emphysema | 1.36 | 1.25 | 1.48 |
| Fall in past 31–180 days | 1.23 | 1.12 | 1.36 |
| Unsteady gait | 1.17 | 1.10 | 1.26 |
| Anti-anxiety Medication | 1.15 | 1.07 | 1.25 |
Discussion
This study suggests that a history of hospitalization for a prior fracture, whether it is a hip fracture or other type of fracture, is a major risk factor for subsequent osteoporotic fractures for nursing home residents. The magnitude of this risk is similar to that observed in community-dwelling adults [6]. The cumulative two-year fracture rate is 23.9% in residents who have a prior hip fracture, highlighting the need for secondary fracture prevention in this group. Lindsey et al. report a similar 19.2% vertebral fracture rate in the first twelve months after the incident vertebral fracture in four-three year clinical trials [9]. Colon-Emeric and colleagues reported the rate of subsequent self-reported fractures after a hip fracture in community dwelling adults was 10.4 fractures/100 person-years [10]. The present study confirms that despite the high prevalence of osteoporosis and other fracture risk factors, prior osteoporotic fractures appear to be a marker for residents at extremely high risk of subsequent fractures.
The characterics of residents who have had a prior hip fracture or other osteoporotic fracture observed in this study were: Caucasian race, female, a history of falls, a history of arthritis, use 10 or more medications, and use antidepressant and hypnotic medications. These characteristics of people are similar to those reported by other groups [11–16] with the exception of arthritis. We postulate that people with arthritis may have a higher risk of falling and thus were more likely to have had a fracture. Furthermore, we cannot determine how many subjects had rheumatoid arthritis, a risk factor for osteoporotic fractures [17]. Nursing home residents who were there for a short stay (less than 90 days) were more likely to have had a prior fracture, probably reflecting the large number of older patients who require short-term rehabilitation in nursing homes after a fracture, possibly biasing against those with a previous fracture.. Several diseases associated with an increased risk of fractures including cerebrovascular accidents and hemiplegia, were less common in the subjects with previous fractures. Although these diseases have all been previously associated with fractures and an increased risk of falling [18–20], each disorder as it progresses limits mobility. Residents with these diseases severe enough to cause admission to a nursing home may have been less mobile than community-dwelling people with the same disease and, thus, less at risk for fracture.
Our study results are consistent with earlier research for four health conditions associated with an increased risk of osteoporotic fractures were identified: depression, emphysema, falls in the past 31–180 days and unsteady gait, as well as the use of antianxiety medication [4,11,15,18,21]. An MDS history of arthritis was again found to be a predictor of fractures and we offer similar interpretations of these data (vide supra). Our findings of decreased risk of subsequent fractures associated wtih cerebrovascular accidents, hemiplegia and diabetes are in contrast to prior research that has identified these conditions as risk factors for fractures [23–26]. Our data are consistent, both prior fractures and subsequent fractures are less commonly seen in patients in our study with neurological conditions. However, a recent study suggests that among people with stroke, those with the greatest risk of fracture, are those with moderate functional impairment; stroke patients with mild or severe impairment are less at risk of fracture [27]. Thus, people who are admitted to nursing homes with a stroke or hemiplegia may have significant functional limitations causing them to be less at risk of fracture. We have no explanation for our finding of an inverse association between diabetes and fractures
Our study has several limitations. First, fracture ascertainment was done by review of hospitalization data. Previous research has shown that Medicare hospital claims can accurately identify hip fractures but are less sensitive to other types of fractures, especially those which are less likely to require hospitalization [28]. Thus, our referent group, those with no history of prior fracture, likely contains individuals who indeed had prior fractures. The inclusion of individuals with prior fracture in the referent group would have the effect of biasing our results to the null, implying that the risks observed in this study are lower-bound estimates of the true risk that might be observed if all subjects could be correctly classified. Second, we did not exclude fractures due to trauma or cancer, and this may have slightly increased the number of observed fractures. Another potential limitation of our study is that our clinical data was obtained from MDS assessments completed in the nursing home. MDS assessments capture the comorbidities and history at the time they are conducted. Health conditions that develop after a nursing home stay would be missed. Previous researchers have found MDS fairly accurate for reporting clinical conditions associated with recent hospitalizations [29]. This is consistent with the instructions for completing the MDS, which indicate only conditions relevant to the nursing home stay should be noted. The ability of MDS to capture and accurately represent the prevalence of all health conditions potentially relevant to hip fracture is unknown. In addition, the MDS did not contain information on the use of osteoporosis prevention medications, so we were unable to identify any patients who were under treatment to prevent future fractures. However, it is unlikely that knowledge of use of fracture protection medications would alter the results observed. An prior study of North Carolina nursing home residents showed low use of osteoporosis medications [30].
These data demonstrate that nursing home residents with prior hip or other fractures warrant interventions to reduce their fracture risk. Several studies have documented that nursing home residents are frequently not treated with therapies that can reduce their subsequent risk of fractures [30–32]. While it is possible that a portion of such patients are not appropriate candidates for osteoporosis treatment due to co-morbidities and life expectancy, we believe this study should prompt evaluations of therapies to reduce the rate of fractures in this high risk population.
Acknowledgments
The analyses upon which this publication is based were performed under Contract No. 500-02-NC03 (“Utilization and Quality Control Peer Review Organization for the State of North Carolina”), funded by the Centers for Medicare & Medicaid Services (CMS), an agency of the U.S. Department of Health and Human Services. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organization imply endorsement by the U.S. Government. The author assumes full responsibility for the accuracy and completeness of the ideas presented.
Grant Support
Supported by the Alliance for Better Bone Health, The Claude A. Pepper Older American Independence Center AG-11268, and the VA Medical Research Service. Dr. Colon-Emeric is supported by a Paul A. Beeson award K23 AG024787.
References
- 1.Wahren GE, Hawkes WG, Hebel JR, et al. Bone mineral density, soft tissue body composition, strength, and functioning after hip fracture. J Gerontol A Bio Sc Med Sci. 2005;60:80–4. doi: 10.1093/gerona/60.1.80. [DOI] [PubMed] [Google Scholar]
- 2.Zimmerman S, Chandler JM, Hawkes W, et al. Effect of fracture on the healthcare use of nursing home residents. Arch Intern Med. 2002;162:1502–8. doi: 10.1001/archinte.162.13.1502. [DOI] [PubMed] [Google Scholar]
- 3.Colon-Emeric SC, Biggs DP, Schenck AP, et al. Risk factors for hip fractures in skilled nursing facilities: Who should be evaluated? Osteoporosis Int. 2003;14:484–9. doi: 10.1007/s00198-003-1384-5. [DOI] [PubMed] [Google Scholar]
- 4.Girman CJ, Chandler JM, Zimmerman SI, et al. Prediction of fracture in nursing home residents. J Amer Geriatrics Soc. 2002;50:1341–47. doi: 10.1046/j.1532-5415.2002.50354.x. [DOI] [PubMed] [Google Scholar]
- 5.Sugarman JR, Connell FA, Hansen A, et al. Hip fracture incidence in nursing home residents and community-dwelling older people, Washington State, 1993–1995. J Amer Geriatrics Soc. 2002;50:1638–43. doi: 10.1046/j.1532-5415.2002.50454.x. [DOI] [PubMed] [Google Scholar]
- 6.Klotzbuecher CM, Ross PD, Landsman PB, et al. Patients with prior fractures have an increased risk of future fractures: a summary of the literature and statistical synthesis. J Bone Miner Res. 2000;15:721–39. doi: 10.1359/jbmr.2000.15.4.721. [DOI] [PubMed] [Google Scholar]
- 7.Rothman KJ, editor. Modern Epidemiology. Little Brown and Company; Boston: 1986. [Google Scholar]
- 8.Hosmer DW, Lemeshow S. Applied Logistic Regression. John Wiley & Sons; New York: 1989. [Google Scholar]
- 9.Lindsay R, Silverman S, Cooper C, et al. Risk of new vertebral fracture in the year following a fracture. JAMA. 2001;285:320–3. doi: 10.1001/jama.285.3.320. [DOI] [PubMed] [Google Scholar]
- 10.Colon-Emeric C, Kuchibhatla M, Pieper C, et al. The contribution of hip fracture to the risk of subsequent fractures: data from two longitudinal studies. Osteoporosis Int. 2003;14:879–83. doi: 10.1007/s00198-003-1460-x. [DOI] [PubMed] [Google Scholar]
- 11.Cummings SR, Nevitt MC, Browner WS, et al. Risk factors for hip fracture in white women. N Engl J Med. 1995;332:767–73. doi: 10.1056/NEJM199503233321202. [DOI] [PubMed] [Google Scholar]
- 12.Johnell O, Kanis JA, Oden A, et al. Predictive Value of BMD for hip and other fractures. J Bone Miner Res. 2005;20:1185–94. doi: 10.1359/JBMR.050304. [DOI] [PubMed] [Google Scholar]
- 13.De Laet CEDH, Van Hout BA, Baurger H, et al. Hip fracture prediction in elderly men and women: validation of the rodermam study. J Bone Miner Res. 1998;13:1587–93. doi: 10.1359/jbmr.1998.13.10.1587. [DOI] [PubMed] [Google Scholar]
- 14.Melton LJ, III, Crowson CS, O’Fallon WM, et al. Relative contributions of bone density, bone turnover and clinical risk factors to long-term fracture prediction. J Bone Miner Res. 2003;18:312–18. doi: 10.1359/jbmr.2003.18.2.312. [DOI] [PubMed] [Google Scholar]
- 15.Taylor BC, Schreiner PJ, Stone KL, et al. Long-term prediction of incident hip fracture risk in elderly white women study of osteoporotic fractures. J Am Geriat Sec. 2004;52:1479–86. doi: 10.1111/j.1532-5415.2004.52410.x. [DOI] [PubMed] [Google Scholar]
- 16.Ensrud KE, Blackwell T, Mangione CM, et al. Central nervous system active medications and risk for fractures in older women. Arch Intern Med. 2003;163:949–57. doi: 10.1001/archinte.163.8.949. [DOI] [PubMed] [Google Scholar]
- 17.Kanis JA, Borgstrom F, De Laet C, et al. Assessment of fracture risk. Osteoporosis Int. 2005;16:581–89. doi: 10.1007/s00198-004-1780-5. [DOI] [PubMed] [Google Scholar]
- 18.Physician’s Guide to Prevention and Treatment of Osteoporosis. National Osteoporosis Foundation; Washington, DC: 2003. [Google Scholar]
- 19.Fink HA, Kuskowski MA, Orwoll ES, et al. Association between parkinsons disease and low bone density and falls in older men: the osteoporotic fractures in men study. J Am Geriatr Soc. 2005;53:1559–64. doi: 10.1111/j.1532-5415.2005.53464.x. [DOI] [PubMed] [Google Scholar]
- 20.Melton LJ, III, Beard CM, Kokmen E, et al. Fracture risk in patients with alzheimer’s disease. J Am Geriatr Soc. 1994;42:614–19. doi: 10.1111/j.1532-5415.1994.tb06859.x. [DOI] [PubMed] [Google Scholar]
- 21.Whooley M, Kip KE, Cauley JA, et al. Depression falls and risk of fracture in older women. Arch Intern Med. 1999;159:484–9. doi: 10.1001/archinte.159.5.484. [DOI] [PubMed] [Google Scholar]
- 22.Robbins J, Hirsch C, Whitmer R, et al. The association of bone mineral density and depression in an older population. J Am Geriatr Soc. 2001;49:732–36. doi: 10.1046/j.1532-5415.2001.49149.x. [DOI] [PubMed] [Google Scholar]
- 23.Ramnemark A, Nilsson M, Borssen B, et al. Stroke, a major and increasing risk factor for femoral neck fractures. Stroke. 2000;31:1572–77. doi: 10.1161/01.str.31.7.1572. [DOI] [PubMed] [Google Scholar]
- 24.Kanis J, Oden A, Hohnell O. Acute and long-term increase in fracture risk after hospitalization for stroke. Stroke. 2001;32:702–6. doi: 10.1161/01.str.32.3.702. [DOI] [PubMed] [Google Scholar]
- 25.Janghorbani M, Feskanich D, Willett WC, Hu F. Prospective study of diabetes and risk of hip fracture: the Nurses’ Health Study. Diabetes Care. 2006;29:1573–8. doi: 10.2337/dc06-0440. [DOI] [PubMed] [Google Scholar]
- 26.Lipscombe LL, Jamal SA, Booth GL, Hawker GA. The risk of hip fractures in older individuals with diabetes: a population-based study. Diabetes Care. 2007;30:835–41. doi: 10.2337/dc06-1851. [DOI] [PubMed] [Google Scholar]
- 27.Whitson HW, Pieper CF, Sander L, et al. Adding injury to insult: fracture risk after stroke in veterans. J Am Geriatr Soc. 2006;54:1082–88. doi: 10.1111/j.1532-5415.2006.00769.x. [DOI] [PubMed] [Google Scholar]
- 28.Ray W, Griffin MR, Fought RL, Adams ML. Identification of fractures from computerized Medicare files. J Clin Epidemiol. 1992;45(7):703–14. doi: 10.1016/0895-4356(92)90047-q. [DOI] [PubMed] [Google Scholar]
- 29.Del Rio RA, Goldman M, Kapella BK, Sulit L, Murray PK. The accuracy of Minimum Data Set diagnoses in describing recent hospitalization at acute care facilities. J Am Med Dir Assoc. 2006;7(4):212–18. doi: 10.1016/j.jamda.2005.12.007. [DOI] [PubMed] [Google Scholar]
- 30.Colon-Emeric C, Lyles KW, Levine DA, et al. Prevalence and predictors of osteoporosis treatment in nursing home residents with known osteoporosis or recent fracture. Osteoporosis Int. 2007;18:553–9. doi: 10.1007/s00198-006-0260-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Jacn AC, Shireman T, Whittle J, et al. Differing patterns of antiresorptive pharmacotherapy among nursing facility residents and community dwellers. J Am Geriatr Soc. 2005;53:1275–81. doi: 10.1111/j.1532-5415.2005.53401.x. [DOI] [PubMed] [Google Scholar]
- 32.Kamel HK. Underutilization of calcium and vitamin D supplements in an academic long-term care facility. J Am Med Dir Assoc. 2004;5:98–100. doi: 10.1097/01.JAM.0000110649.22467.B4. [DOI] [PubMed] [Google Scholar]