Hospitalizations for fracture in patients with metastatic disease: primary source lesions in the United States
Background Breast, lung, thyroid, kidney, and prostate cancers have high rates of metastasis to bone in cadaveric studies. However, bone metastasis at time of death may be less clinically relevant than occurrence of pathologic fracture and related morbidity. No population-based studies have examined the economic burden from pathologic fractures.
Objectives To determine primary tumors in patients hospitalized with metastatic disease who sustain pathologic and nonpathologic (traumatic) fractures, and to estimate the costs and lengths of stay for associated hospitalizations in patients with metastatic disease and fracture.
Methods The Healthcare Cost and Utilization Project’s National (Nationwide) Inpatient Sample was used to retrospectively identify patients with metastatic disease in the United States who had been hospitalized with pathologic or nonpathologic fracture during from 2003-2010. Patients with pathologic fracture were compared with patients with nonpathologic fractures and those without fractures.
Results Of 674,680 hospitalizations of patients with metastatic disease, 17,313 hospitalizations were for pathologic fractures and 12,770 were for nonpathologic fractures. The most common primary cancers in patients hospitalized for fractures were lung (187,059 hospitalizations; 5,652 pathologic fractures; 3% of hospitalizations were for pathologic fractures), breast (124,303; 5,252; 4.2%), prostate (79,052; 2,233; 2.8%), kidney (32,263; 1,765; 5.5%), and colorectal carcinoma (172,039; 940; 0.5%). Kidney cancer had the highest rate of hospitalization for pathologic fracture (24 hospitalizations/1,000 newly diagnosed cases). Patients hospitalized for pathologic fracture had higher billed costs and longer length of stay.
Limitations Hospital administrative discharge data includes only billed charges from the inpatient hospitalization.
Conclusion Metastatic lung, breast, prostate, kidney, and colorectal carcinoma are commonly seen in patients hospitalized with pathologic fracture. Pathologic fracture is associated with higher costs and longer hospitalization.
Funding Grants from the NIH (K08 AR060164-01A), American Society for Surgery of the Hand Hand Surgeon Scientist Award grant, and University of Rochester Medical Center Clinical & Translational Science Institute grants, in addition to institutional support from the University of Rochester and Pennsylvania State University Medical Centers.
Accepted for publication November 21, 2017
Correspondence openelfar@gmail.com
Disclosures The authors report no disclosures/conflicts of interest.
Citation JCSO 2018;16(1):e14-e20
©2018 Frontline Medical Communications
doi https://doi.org/10.12788/jcso.0385
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Limitations
This study is subject to the limitations of a retrospective analysis based on hospital administrative discharge data. It evaluates only billed charges and does not account for costs associated with rehabilitation stays. However, it represents a stratified cross-sample of hospitalizations in the United States, in both teaching and nonteaching hospitals, and is the largest study to date that the authors are aware of looking at the burden of pathologic fractures in patients with metastatic disease.
This study specifically included only patients with metastatic disease, which therefore limits comparisons with the rate of hospitalization for nonpathologic fracture in patients without metastatic disease. Patients with metastatic disease who were not hospitalized during the study period are nevertheless at risk for fracture but would not have been captured in this study. It is also likely that some patients with metastatic disease had multiple hospitalizations, including some that were not for fracture; therefore, this study likely underestimates the percentage of patients with metastatic disease who sustain pathologic and nonpathologic fracture.
Some patients were excluded because we were not able to identify a primary cancer from hospital discharge records. The lack of an included diagnosis may be a result of indeterminate primary during the fracture admission or may represent a failure to accurately code a primary, known cancer. Although the NIS does not permit identification of these patients to determine if a primary cancer was subsequently identified, future studies using other databases may target patients presenting with pathologic fracture and an unknown primary tumor to evaluate subsequent cancer diagnosis.
Summary
The significance of bone metastasis in causing pathologic fractures in lung, breast, prostate, and kidney cancers was confirmed. Colorectal carcinoma has been established as the fifth most common primary cancer in patients with metastatic disease who are hospitalized with pathologic fracture, and a large number of patients with metastatic CRC sustain nonpathologic fractures requiring hospitalization. In patients with metastatic CRC or new skeletal pain, education on fall prevention and increased vigilance should be considered. Further studies are needed to determine the best method for prevention of pathologic fractures in all highly prevalent cancers, with previous hospitalizations without fracture as an appropriate target. Previous paradigms about which cancers metastasize to bone should be reconsidered in the context of which lead to clinically important fractures and hospitalization.
