Research Summary: Research topic:
Investigating Medicare claims data to determine the incidence and risk factors for venous thromboembolism (VTE) following upper limb arthroplasty.
Analysis of data associated with patients who've had shoulder and elbow arthroplasty (compared to hip and knee arthroplasty) will enable researchers to estimate the national incidence of thromboembolism and evaluate the effect of patient, hospital and surgeon factors.
Patient care application of results:
Establish the risk of thromboembolism following shoulder and elbow arthroplasty to determine if measures that will decrease the risk of thromboembolism—such as use of prophylactic anticoagulants—should be considered.
Simplified patient care application of results:
Taking measures with the least associated risks to prevent clots in patients who've undergone shoulder or elbow arthroplasty. VTE Following Shoulder and Elbow Arthroplasty: Incidence and Risk Factors
OREF grant recipient hopes to reduce thromboembolic events Jay D. Lenn
“I’m a clinician and a scientist both—a little bit out of curiosity and a little bit out of desperation,” mused Matthew L. Ramsey, MD. “There’s the curiosity to figure out why things work and find better ways to do things. The desperation comes in when you move from training into the real world where there are a lot of questions and a lot of issues we really don’t have answers to.”
Curiosity and desperation provided the impetus for Dr. Ramsey’s current investigation of the incidence of venous thromboembolism after shoulder and elbow arthroplasty, as well as factors that may increase the risk of this complication. Dr. Ramsey, associate professor of orthopaedic surgery at Thomas Jefferson University in Philadelphia, explained that his interest began with a patient who had a pulmonary embolism after a total elbow replacement.
Not having encountered the problem before with an upper limb surgery, he found the experience had a profound effect on him. He began looking into the literature, but found very little research about the phenomenon. While a number of subsequent studies have concluded that the incidence is low compared with the incidence following lower limb surgeries, Dr. Ramsey found limitations in those studies that leave significant and relevant gaps in what is known about thromboembolism.
In 2009, Dr. Ramsey was awarded an OREF/ASES/Rockwood Clinical Research Grant in Shoulder Care to analyze Medicare claims data to determine the nationwide incidence of thromboembolism after upper-limb arthroplasty and to identify associated risk factors. The OREF/ASES/Rockwood Grant, which is offered to members of American Shoulder and Elbow Surgeons (ASES), is made possible through a contribution from the family of Charles A. Rockwood Jr., MD. Identifying gaps in the research
Dr. Ramsey described two general limitations in the current body of knowledge that suggests a low incidence of thromboembolism after shoulder or elbow arthroplasty. First, some reports were based on the outcome of procedures conducted by highly specialized
surgeons at a single tertiary care center. (1, 2) Data from such institutions—which likely have unique patient selection, surgeon experience and surgical time—may not reflect the typical national experience.
A second limitation, noted Dr. Ramsey, is apparent in an analysis of New York State Hospital discharge data that also demonstrated a low incidence.(3) That research only included data from thromboembolic events prior to discharge. The risk of deep vein thrombosis after hip and knee replacement surgery may continue for as much as three months after surgery. And there are generally two peak times for risk: two to five days after surgery, when a patient is likely in the hospital; and 10 days after surgery, when most patients have been discharged.(4)
A similar delayed event might reasonably be expected following upper limb arthroplasty. Dr. Ramsey explained that thromboembolic events following discharge would not have been observed in the New York State study and that hospital stays for shoulder and elbow replacements are generally shorter than for lower-limb procedures. Broadening the scope of investigation
To address the gaps in this information, Dr. Ramsey and his colleagues will examine Medicare claims data from 1997 to 2006. Patient identities aren’t revealed to the researchers, but identification numbers enable them to see the International Classification of Diseases codes and other relevant data associated with each patient, including:
• Demographic information, such as age, race and gender
• Comorbidities one year prior to arthroplasty, including obesity
• Diagnosis indicating surgery
• Type of surgery for shoulder and elbow
• Complications up to three months after surgery: deep vein thrombosis, pulmonary embolism and death
• Hospital size and teaching status
• Length of hospital stay
• Anesthesia time
Analysis of the data should enable Dr. Ramsey and his research team to estimate the national incidence of thromboembolism following upper extremity arthroplasty and to evaluate the effect of patient, hospital and surgeon factors. Making informed choices
The outcome of this research could have important implications for treatment decisions. Prophylactic use of anticoagulants is the standard of care to reduce the risk of thromboembolism following hip and knee replacement. However, there are significant risks associated with anticoagulation that must be balanced against the risk of thromboembolism.
If there is a significant risk associated with shoulder and elbow surgery—or a particular patient profile associated with a risk—then anticoagulants might be appropriate in some cases.
Dr. Ramsey explained, “When I talk to my patients, I tell them that in medicine, as in life, you don’t get something for nothing. What you’re going to get out of the deal is a shiny new shoulder that will improve your function and diminish your pain, but there are certain risks to that surgery. One of them being the potential for a venous clot or pulmonary embolism.”
Currently, there’s no consensus on the nature of that risk or what to do about it. Dr. Ramsey explained that there isn’t enough data for the doctor or patient to understand the relative risk of developing thromboembolism compared with the risk associated with prophylactic anticoagulants.
He added, “The question for the patient is, how much risk are you willing to assume? And for me, as the surgeon, how much risk am I willing to assume? When there’s risk on either side and I can’t answer a patient’s question about the relative risk of each, that makes me a little uncomfortable—and that drives me to find the answer.”
1 Duncan SF, Sperling JW, Morrey BF: Prevalence of pulmonary embolism after total elbow arthroplasty. The Journal of Bone and Joint Surgery. 2007 Jul;89(7):1452-3.
2 Sperling JW, Cofield RH: Pulmonary embolism following shoulder arthroplasty. The Journal of Bone and Joint Surgery. 2002 Nov;84-A(11):1939-41.
3 Lyman S, Sherman S, Carter TI, Bach PB, Mandl LA, Marx RG: Prevalence and risk factors for symptomatic thromboembolic events after shoulder arthroplasty. Clinical Orthopaedics and Related Research. 2006 Jul;448:152-6.
4 Deep vein thrombosis. American Academy of Orthopaedic Surgeons. http://www.orthoinfo.org/topic.cfm?topic=A00219.
Accessed April 5, 2011