Trends in the Incidence and In-Hospital Outcomes of Elective Major Orthopaedic Surgery in Patients Eighty Years of Age and Older in the United States from 2000 to 2009

Yoshihara, Hiroyuki MD, PhD; Yoneoka, Daisuke MS

Journal of Bone & Joint Surgery - American Volume: 16 July 2014 - Volume 96 - Issue 14 - p 1185–1191
doi: 10.2106/JBJS.M.01126
Scientific Articles

Background: Although life expectancy continues to increase worldwide and advances occur in surgical techniques and medical treatment, the chronological age limit for patients to undergo elective major orthopaedic procedures remains a controversial subject. The purpose of this study was to examine the trends in the incidence and in-hospital outcomes of elective major orthopaedic surgery in patients eighty years of age and older in the United States as a whole.

Methods: ICD-9-CM (International Classification of Diseases, 9th Revision, Clinical Modification) codes were used to identify patients at least eighty years of age in the Nationwide Inpatient Sample who underwent spinal fusion, total hip arthroplasty, or total knee arthroplasty from 2000 to 2009. Demographic data regarding the patient and health-care system were retrieved and analyzed.

Results: From 2000 to 2009, there were increasing trends in the age-adjusted incidence of spinal fusion, total hip arthroplasty, and total knee arthroplasty in patients at least eighty years of age (rate per 100,000 per year, 40 to 102 for spinal fusion, 181 to 257 for total hip arthroplasty, and 300 to 477 for total knee arthroplasty; p ≤ 0.001 for each). The overall in-hospital complication rate remained stable over time for spinal fusion and total knee arthroplasty and increased for total hip arthroplasty (9.0% to 10.3%, p = 0.008). The in-hospital mortality rate decreased over time (1.1% to 0.6% for spinal fusion, 0.5% to 0.3% for total hip arthroplasty, and 0.3% to 0.2% for total knee arthroplasty; p < 0.05 for each). The overall in-hospital complication and mortality rates of patients at least eighty years of age were significantly higher than those of patients sixty-five to seventy-nine years of age (p < 0.001 for both).

Conclusions: During the previous decade, the rates of elective major orthopaedic surgical procedures in patients at least eighty years of age increased in the U.S. The in-hospital mortality rates decreased, whereas the overall in-hospital complication rates remained stable or increased. The overall event rates were low, and these elective procedures could be offered to very elderly patients.

Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

1Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, 301 East 17th Street, New York, NY 10003. E-mail address: hiroyoshihara55@yahoo.co.jp

2Department of Statistical Science, School of Advanced Sciences, The Graduate University for Advanced Studies, 10-3 Midori-machi, Tachikawa, Tokyo 190-8562, Japan

Article Outline

Life expectancy continues to increase all over the world. According to U.S. Census Bureau data released on March 9, 2006, individuals at least eighty-five years of age now represent the fastest-growing demographic in the U.S.1, and they are projected to account for 2.3% of the U.S. population in 2030 and 4.3% in 20502. In accordance with this trend, surgical treatment for very elderly people has been increasing. For example, cardiac revascularization and valve repair surgery for those eighty to eighty-nine years of age has increased in the past twenty years, and this trend will likely continue3,4. Very elderly patients have multiple risk factors, including their general condition, comorbidities, and pathophysiological changes, that may result in more adverse outcomes after surgery5. Therefore, performance of elective surgical procedures to increase quality of life in individuals of advanced age may be controversial.

Major orthopaedic procedures such as spinal fusion, total hip arthroplasty, and total knee arthroplasty are performed predominantly on an elective basis to alleviate pain and to increase quality of life. In the present study, we examined the trends and in-hospital patient outcomes of elective major orthopaedic surgical procedures in patients at least eighty years of age in the U.S. from 2000 to 2009 by analyzing the population-based national hospital discharge data collected for the Nationwide Inpatient Sample (NIS). We also compared outcomes such as complications and mortality in patients at least eighty years of age with those in patients sixty-five to seventy-nine years of age.

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Materials and Methods

Data Source

The NIS is the largest all-payer inpatient care database in the U.S. and contains data from approximately eight million stays at 1000 hospitals each year. The data comprise a 20% stratified sample of all community hospitals in the U.S.6. Every entry in the database represents a single hospitalization record. Records in the NIS database include discharge and hospital information that was used to generate national estimates in the present analysis.

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Patient Selection

A retrospective analysis utilizing the NIS hospital discharge data from 2000 to 2009 was performed. ICD-9-CM (International Classification of Diseases, 9th Revision, Clinical Modification) codes 81.51 and 81.54 were used to identify discharges following primary total hip arthroplasty and primary total knee arthroplasty, respectively. Discharges following spinal fusion were identified with use of Clinical Classification Software (CCS) code 158. (The CCS is a tool devised by the Agency for Healthcare Research and Quality [AHRQ] that combines the relevant ICD-9-CM procedure codes into clinically meaningful groups.) Patients at least eighty years of age and those sixty-five to seventy-nine years of age who underwent these procedures were included in the study if the records included the code signifying elective admission, ATYPE 3 (thus excluding patients with an emergency or urgent admission for a reason such as fracture).

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Patient and Health-Care System Characteristics

Patient age, sex, race, comorbidities, complications, mortality, duration of hospital stay, discharge disposition, and total hospital charges were extracted from the NIS. Patients were also categorized according to race as “white,” “black,” “Hispanic,” “others,” or “not stated.” Comorbidities were assessed with use of the Elixhauser method, a well-established technique for identifying comorbidities from administrative databases7. The Elixhauser comorbidity index, which includes a set of thirty medical comorbidities, is one of the best comorbidity indices for predicting the outcome of patients in administrative databases8. A total comorbidity score was determined for each case by adding 1 point per comorbidity. In-hospital complications of the following types were identified on the basis of the indicated ICD-9-CM codes: neurologic complications (997.00-997.09); respiratory complications (518.4, 518.5, 518.81-518.84, 997.3); cardiac complications (410, 997.1); gastrointestinal complications (535.0, 570, 575.0, 577.0, 997.4); urinary and renal complications (584, 997.5); pulmonary embolism (415.1); and wound-related complications, including infection, dehiscence, seroma, and hematoma (998.1, 998.3, 998.5, 998.83, 999.3). Four-digit and five-digit codes were also included under the respective three-digit and four-digit codes (e.g., 41000 was included under 410). Patient disposition was categorized as “routine,” “transfer to short-term hospital,” “other transfers,” “home health care,” “died in hospital,” or “other.” “Other” transfers include transfer to a skilled nursing facility, intermediate care facility, or another type of facility.

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Data Analysis

Categorical patient data were retrieved from the NIS, and discharge weights supplied by the AHRQ were applied to calculate national estimates from the NIS data. U.S. population data for 2000 to 2009 were obtained from the U.S. Census Bureau web site9. The incidences of spinal fusion, total hip arthroplasty, and total knee arthroplasty in the U.S. in each age group during a given year were calculated by dividing the national estimate of procedures by the estimated national population of the age group obtained from the U.S. Census Bureau data for that year. A linear regression model was then applied to analyze the time trend. The chi-square test was used to assess the equality of proportions, and the Fisher exact test was used to assess differences between proportions of patients at least eighty years of age and those sixty-five to seventy-nine years of age. The Student t test was used to compare the mean value of continuous variables between the two age groups. Correction for multiple comparisons was performed with use of the Holm method. R statistical software (version 2.15.1; R Foundation for Statistical Computing) was used for the statistical analyses. A p value of 0.05 was considered significant.

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Source of Funding

There was no external source of funding.

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Results

Patient Demographics and Hospital Characteristics (See Appendix)

Of the patients in the NIS database who were at least eighty years of age, 70,203 underwent spinal fusion, 233,277 underwent total hip arthroplasty, and 417,460 underwent total knee arthroplasty from 2000 to 2009. For the patients who were sixty-five to seventy-nine years of age, the corresponding numbers were 522,369, 768,999, and 1,868,983.

Of the patients treated with spinal fusion who were at least eighty years of age, 55,663 (79.3%) were eighty to eighty-four years, 13,069 (18.6%) were eighty-five to eighty-nine years, and 1472 (2.1%) were at least ninety years. Of the patients treated with total hip arthroplasty who were at least eighty years of age, 160,715 (68.9%) were eighty to eighty-four years, 60,737 (26.0%) were eighty-five to eighty-nine years, and 11,825 (5.1%) were at least ninety years. Of the patients treated with total knee arthroplasty who were at least eighty years of age, 308,652 (73.9%) were eighty to eighty-four years, 96,822 (23.2%) were eighty-five to eighty-nine years, and 11,987 (2.9%) were at least ninety years.

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Incidence of Elective Major Orthopaedic Surgical Procedures

The age-adjusted incidence in patients at least eighty years of age increased over time for each of the three procedures. The incidence per 100,000 per year increased over time from 2000 to 2009 for spinal fusion (from 40 to 102, p < 0.001), for total hip arthroplasty (from 181 to 257, p < 0.001), and for total knee arthroplasty (from 300 to 477, p = 0.001) (Fig. 1).

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Comorbidities and In-Hospital Complications and Mortality Rates

The mean Elixhauser comorbidity index of patients at least eighty years of age was 1.9 for those treated with spinal fusion from 2000 to 2009, 1.8 for those treated with total hip arthroplasty, and 1.8 for those treated with total knee arthroplasty. The scores increased over time from 2000 to 2009 (p < 0.001) for spinal fusion (from 1.4 to 2.1), for total hip arthroplasty (from 1.4 to 2.2), and for total knee arthroplasty (from 1.4 to 2.2) (see Appendix).

Detailed in-hospital complication rates are shown in Table I. The overall in-hospital complication rate remained stable over time from 2000 to 2009 for spinal fusion (from 17.5% to 16.1%, p = 0.230) and for total knee arthroplasty (from 9.9% to 9.1%, p = 0.999) but increased over time for total hip arthroplasty (from 9.0% to 10.3%, p = 0.008) (Fig. 2). The trends in the overall in-hospital complication rate stratified according to the number of comorbidities are shown in Table II. The in-hospital mortality rate averaged 0.9% for spinal fusion, 0.5% for total hip arthroplasty, and 0.3% for total knee arthroplasty and decreased over time from 2000 to 2009 for spinal fusion (from 1.1% to 0.6%, p = 0.026), for total hip arthroplasty (from 0.5% to 0.3%, p = 0.028), and for total knee arthroplasty (from 0.3% to 0.2%, p = 0.014) (Table I, Fig. 3).

The overall in-hospital complication rate and the in-hospital mortality rate were significantly higher for patients at least eighty years of age compared with those sixty-five to seventy-nine years of age for all three procedures (p < 0.001 for all, Table I).

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Duration of Hospital Stay and Disposition

For patients at least eighty years of age, the duration of hospital stay averaged 4.9 days for spinal fusion, 4.3 days for total hip arthroplasty, and 4.1 days for total knee arthroplasty. The duration decreased over time from 2000 to 2009 (p < 0.001) for spinal fusion (from 5.6 to 4.2 days), for total hip arthroplasty (from 4.7 to 3.9 days), and for total knee arthroplasty (from 4.6 to 3.7 days) (Table I; see Appendix).

The proportion of patients at least eighty years of age who were discharged home with home health care averaged 13.9% for spinal fusion, 12.7% for total hip arthroplasty, and 17.1% for total knee arthroplasty. The proportion increased over time from 2000 to 2009 (p < 0.001) for spinal fusion (from 9.6% to 16.4%), for total hip arthroplasty (from 7.9% to 17.7%), and for total knee arthroplasty (from 9.6% to 21.6%) (Table I; see Appendix).

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Discussion

This study demonstrated the increasing trends in the age-adjusted incidence of spinal fusion, total hip arthroplasty, and total knee arthroplasty in patients at least eighty years of age in the U.S. during the previous decade. Singh et al.10 reported a population-based analysis of the trends in the use of total hip arthroplasty and total knee arthroplasty in Olmsted County, Minnesota, from 1969 to 2008. In their study, the age-adjusted rates of total hip arthroplasty and total knee arthroplasty in patients at least eighty years of age increased among the most recent three four-year periods (1997 to 2000, 2001 to 2004, and 2005 to 2008). Previous studies utilizing the NIS indicated temporal changes in anterior cervical decompression and fusion (ACDF), total hip arthroplasty, and total knee arthroplasty in patients sixty-five to eighty-four years of age and in patients at least eighty-five years of age among three five-year periods (1990 to 1994, 1995 to 1999, and 2000 to 2004)11-13. Marawar et al.11 reported an increasing trend in the age-adjusted rate of ACDF in both age groups. Liu et al.12 reported an increasing trend in the age-adjusted rate of total hip arthroplasty in patients sixty-five to eighty-four years of age but a decreasing trend in patients at least eighty-five years of age. Memtsoudis et al.13 reported an increasing trend in the age-adjusted rate of total knee arthroplasty in both age groups. In the present study, we analyzed the rates in every year during the previous decade and demonstrated an increasing trend in the rate of each of the three elective procedures in patients at least eighty years of age.

Comorbidities in patients at least eighty years of age who underwent spinal fusion, total hip arthroplasty, and total knee arthroplasty increased over time. This suggests that surgical treatment was performed for more severely ill patients and that the indication for surgical treatment was broadened; however, it might also reflect use of better technology to detect these diseases as well as increasing patient awareness of these common medical conditions, leading to increased vigilance and earlier detection11. The incidence of chronic disease increases with age14, and the mean Elixhauser comorbidity index of patients at least eighty years of age was higher than that of patients sixty-five to seventy-nine years of age for each of the three elective procedures in the present study. This is consistent with the results of a study by Nie et al.5 that indicated a significantly greater number of preoperative comorbid conditions in very elderly patients (eighty to eighty-nine years of age) compared with middle-aged patients (forty to sixty years) who underwent unilateral laminectomy and discectomy. In contrast, Kreder et al.15 reported that there was no significant difference in the frequency of comorbid factors between patients at least eighty years of age and those sixty-five to seventy-nine years of age who underwent total hip arthroplasty and total knee arthroplasty.

The overall in-hospital complication rate remained stable over time in patients at least eighty years of age who underwent spinal fusion and total knee arthroplasty, and it increased over time in those who underwent total hip arthroplasty. In contrast, the complication rates of all three procedures in patients sixty-five to seventy-nine years of age remained stable over time. These findings may indicate that more careful attention to patient selection, surgical indications, and aggressive perioperative treatment is necessary for patients at least eighty years of age who are being considered for total hip arthroplasty. In addition, the overall in-hospital complication rate in patients at least eighty years of age was significantly higher than that in patients sixty-five to seventy-nine years of age for each of the three procedures; thus, patients at least eighty years of age need to know and accept the higher risk. However, the overall in-hospital complication rate in patients at least eighty years of age with few or no comorbidities decreased significantly over time in those who underwent spinal fusion or total knee arthroplasty, and it did not change significantly in those who underwent total hip arthroplasty. The complication rate increased with the number of comorbidities for each of the three procedures. Therefore, these elective procedures may be better indicated for very elderly patients if they have few or no comorbidities. Despite stable or increasing in-hospital complication rates, the in-hospital mortality rate decreased over time for each of the three procedures. This finding may reflect improvements in medical treatment of complications over the previous decade. However, the mortality rate was slightly but significantly higher than that in patients sixty-five to seventy-nine years of age. Oldridge et al.16 identified an age of eighty to eighty-five years as a threshold for a dramatic increase in in-hospital mortality. The present study reinforces the fact that patients at least eighty years of age need to know and accept the higher risk.

The duration of hospital stay of patients at least eighty years of age decreased over time for each of the three elective procedures. In addition, although the duration of hospital stay of patients at least eighty years of age was significantly longer than that of patients sixty-five to seventy-nine years of age, the absolute difference was small. The proportion of patients who were discharged home (routine or home health care disposition) increased over time. These results demonstrate excellent outcomes following the elective major orthopaedic surgical procedures in very elderly patients. Transfers to another institution such as a rehabilitation facility generally take extra time and make the duration of hospital stay longer. Therefore, the increasing trend in the proportion of patients who were discharged home may reflect the decreasing trend in the duration of hospital stay. The proportion of patients who were discharged home with home health care increased over time. This indicates that, although an increasing proportion of patients were deemed well enough to go home, they needed some type of care such as physical therapy.

The present study was limited by several factors inherent to the retrospective analysis of large administrative databases. Data entry may be subject to some degree of coding or reporting bias; however, reporting quality should not vary substantially within the database. The data were limited to in-hospital events, and the true incidence of complications and mortality may therefore have been underestimated. The NIS database does not include clinical outcomes. Despite these limitations, we believe that the results give a reasonable picture of the trends and in-hospital outcomes of elective major orthopaedic surgical procedures in elderly patients in the U.S. during the previous decade.

In summary, elective major orthopaedic surgical procedures in patients at least eighty years of age increased in the U.S. during the previous decade. Although the overall in-hospital complication rate remained stable for spinal fusion and total knee arthroplasty and increased for total hip arthroplasty, the rate in patients with few or no comorbidities decreased significantly for spinal fusion and total knee arthroplasty and did not change significantly for total hip arthroplasty. The in-hospital mortality rate decreased over time for each of the three procedures. Although the overall in-hospital complication and mortality rates in patients at least eighty years of age were significantly higher than those in patients sixty-five to seventy-nine years of age for each of the three procedures, the absolute differences were small. The results indicated that the overall event rates were low and that these elective procedures could therefore be offered to very elderly patients as long as they accept the risks. Very elderly patients who have had inadequate results from exhaustive nonsurgical or conservative treatment, particularly those with few or no comorbidities, may still benefit from these elective surgical procedures.

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Appendix Cited Here...

A table summarizing patient demographics and figures showing trends in the comorbidity index, duration of hospital stay, and discharge to home with home health care are available with the online version of this article as a data supplement at jbjs.org.

Investigation performed at the Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, NY, and The Graduate University for Advanced Studies, Tachikawa, Tokyo, Japan

Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.

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