Incidence of DVT Post- Hip or Knee Replacement. A Comparison of Incidence at Boundary Trails Health Centre to a Credible Baseline Incidence

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1 Incidence of DVT Post- Hip or Knee Replacement A Comparison of Incidence at Boundary Trails Health Centre to a Credible Baseline Incidence

2 Background DVTs Pulmonary Embolisms Death Symptomatic DVTs (leg swelling, pain, etc.) are more likely to produce a pulmonary embolism DVTs are a relatively early complication (2-3 weeks) Ultrasound = Diagnosis

3 The Problem: Are we at Boundary Trails ordering too many ultrasounds for the investigation of post-op DVTs? What is the actual incidence of post-op DVT at Boundary? How does it compare to a more global incidence?

4 Objectives: To compare local incidence of symptomatic Deep Vein Thrombosis (DVT) as diagnosed by ultrasound following major surgery of the lower limbs to a credible baseline. Methods: Radiology and Medical Records were consulted at BTHC. A list of all patients who had undergone Total Hip Arthroplasty (THA) or Total Knee Arthroplasty (TKA) in the last fiscal year was generated. This list was then cross referenced with a list of all patients who had undergone a unilateral or bilateral ultrasound of the leg in the last fiscal year. The common charts were then pulled for further analysis, including the type of surgery and how many days post-operatively they were investigated for a DVT.

5 The Global Baseline Obtained from a meta-analysis of 47 studies, conducted by Januel et. al. In total, almost 45,000 patients were studied. Mostly North American data and some European studies included. Looked only at symptomatic DVTs occuring in the predischarge period and only in patients who had received DVT chemoprophylaxis prior to THA/TKA. These parameters also encapsulate the population of interest at BTHC. Results: Pooled incidence (THA) 0.53%; Pooled incidence (TKA) 1.09%

6 Results: Type of Surgery # of Days Post-Op on Which the Investigation Was Performed Ultrasound Result for DVT TKA 4 Negative TKA 3 Negative THA 4 Negative THA 4 Negative THA 4 Negative

7 Results: Combined number of THAs and TKAs done in the last fiscal year = 443 Total number of patients investigated by U/S for a DVT = 5 Therefore, only 1.1% of the THA and TKA population was even investigated for a DVT.

8 Discussion and Limitations: Only looked at the pre-discharge period. Most DVTs occur within the first 2-3 weeks of surgery. Incidence of DVT may therefore have increased if patients could have been followed for longer periods. Didn t account for other risk factors Potentially didn t capture all of the people who were investigated for DVT use of other diagnostic codes?

9 Further Questions: Would the incidence of ultrasound investigations increase if patients remained in the hospital longer or were followed beyond discharge? The BTHC data suggests a slight disposition for THA to progress to DVT investigation. Does THA carry a greater risk of DVT than TKA?

10 Conclusions Although this data set was unexpectedly small, it suggests that BTHC is not ordering ultrasounds for the purpose of DVT investigation following THA or TKA in excess. Local incidence of DVT at BTHC was 0% in the last fiscal year. Only 1.1% of those who underwent THA or TKA at BTHC in the last fiscal year were investigated for DVT.

11 References 1. American Academy of Orthopaedic Surgeons Deep Vein Thrombosis Januel, J., Guanmin, C., C. Ruffieux Symptomatic In-Hospital Deep Vein Thrombosis and Pulmonary Embolism Following Hip and Knee Arthroplasty Among Patients Receiving Recommended Prophylaxis. The Journal of the American Medical Association. 307(3): Pederson, A Venous Thromboembolism in Patients Having Knee Replacement and Receiving Thromboprophylaxis. The Journal of Bone and Joint Surgery. 93(14): Seung, Y., Du, H., Y. Chin Incidence of Deep Vein Thrombosis after Major Lower Limb Orthopedic Surgery: Analysis of a Nationwide Claim Registry. Yonsei Medical Journal. 56(1):