Synovasure® Alpha Defensin is a Lab Developed Test (LDT) that uses synovial fluid for the diagnosis of joint infection. The test is available in two formats: Synovasure Alpha Defensin test for Periprosthetic Joint Infection (PJI) and Synovasure Alpha Defensin for Native Septic Arthritis (NSA).
The Synovasure Alpha Defensin PJI Test includes 2 measurements: (1) an immunoassay measurement of synovial fluid alpha defensin levels, and (2) an immunoassay measurement of synovial fluid CRP.
The Synovasure Alpha Defensin NSA Test also includes 2 measurements: (1) an immunoassay measurement of synovial fluid alpha defensin levels, and (2) an immunoassay measurement of lactate.
Synovial fluid alpha defensin level is highly accurate in diagnosing periprosthetic joint infection (PJI). The sensitivity of synovial fluid alpha defensin levels for PJI is 97% and the specificity of synovial fluid alpha defensin levels for PJI is 96%. The Synovasure Alpha Defensin test for PJI has been validated against the Musculoskeletal Infection Society (MSIS) guidelines for the diagnosis of PJI.
The false positive rate associated with synovial fluid alpha defensin is ~4%. In our studies, we found that these false positive alpha defensin samples could frequently be identified by their concurrently low synovial fluid CRP value (<3mg/L). Therefore, when the scenario of a high alpha defensin levels and a low CRP in the synovial fluid occurs, we report an accompanying warning that the Synovasure® Alpha Defensin result could potentially be a false positive. For these cases, we recommend that the physician consider all clinical information for final diagnosis.
In our studies, Synovasure® has outperformed the LE test strip in both accuracy and the ability to provide valid results. Our data and other studies have shown that the sensitivity of the LE test strip is approximately 80%. The leukocyte esterase test strip also yields a high proportion of unreadable samples due to blood contamination in the synovial fluid (up to 30%).
Synovasure® Alpha Defensin is intended to assess an arthroplasty for Periprosthetic Joint Infection (PJI) prior to surgical revision. At this time, there are studies underway to assess the accuracy of Synovasure Alpha Defensin for PJI in the setting of a reimplantation.
Saline washing is not approved as a collection method for Synovasure® Alpha Defensin, as this will dilute the protein levels in the synovial fluid and potentially yield false negative results.
In the 158 patient study described in the Synovasure® white paper, 27% of infected patients had been treated with antibiotics prior to aspiration. All of these patients had a positive Synovasure Alpha Defensin test for PJI, and the mean alpha defensin level was not different when comparing infected patients being treated with antibiotics versus those not on an antibiotic program.
Several studies have evaluated the performance of Synovasure® Alpha Defensin using the Musculoskeletal Infection Society (MSIS) definition of infection as the “gold standard”.
After the test is completed, results can be sent via email or fax, as noted as the preferred method by practice upon enrollment with CD Diagnostics®. Results can also be accessed online.
Synovasure® results are intended to be used in conjunction with other clinical and diagnostic findings to aid a patient’s diagnosis. Synovasure is intended to determine whether there is an infection present in the synovial fluid at a joint arthroplasty. It is not intended to identify a specific type of infection or establish the origin or severity of an infection. It is intended to provide a physician with a specific positive or negative result for the presence of the alpha-defensin biomarker that is released into the synovial fluid by the patient’s cells while fighting an infection.
Synovasure® provides a positive or negative result for alpha defensin. Standard culture methods are available at CD Laboratories® for the identification of the organism. The initial Synovasure result will be reported within 24-48 hours of sample receipt, but the culture results (if requested) will be reported as “pending” until the test is complete. Culture negative results are reported after they are negative for the full culture period.
The physician’s office can track the shipment using the tracking number on the FedEx return label (or photocopy the label) on the pouch provided.
There are specific instructions on the Test Submission Document to ensure that the samples are picked up and delivered in a timely fashion. To schedule your “prepaid pickup”. Call 1-800-463-3339 (1-800-GOFEDEX) or schedule online through www.fedex.com.
Note: Packages CANNOT be placed in a FedEx dropbox.
Fill out the Synovasure® Enrollment document and fax to CD Diagnostics® at 443-279-8379. Enrollment is typically processed within 24 hours of receipt. Once received, you will be sent kits to have on hand in your office. Next, ask your Zimmer Biomet rep to familiarize your staff with the paperwork and submission process. Finally, make sure you always have 2-3 Synovasure kits readily accessible in your practice or satellite office. If you need more kits, contact CD Diagnostics Customer Service at 888-981-8378. Once you are shipping samples routinely, you will receive kits by auto replenishment.
The Synovasure® Comprehensive Infection kit contains the materials needed to send synovial fluid to CD Laboratories® includes:
- Submission Instructions Sheet
- 95 kPa Specimen Transport Biohazard Bag
- Specimen Tubes (2 clear top, red stopper and 1 Lavender top)
- Test Requisition Form
- Biological Specimen Box
- Prepaid FedEx Pouch for Biological Specimens
- Prepaid FedEx shipping label
Note: Clinical laboratory kits do not include forms or specimen tubes. Forms are provided electronically upon enrollment.
If you aspirate a synovial fluid sample on Friday or over the weekend, please refrigerate the specimen and ship it on Monday for Tuesday delivery. A sample can be refrigerated for up to 3 days.
Synovasure® is exclusively serviced by CD Laboratories®, a subsidiary of Zimmer Biomet. At the laboratory, results are determined and returned to the clinician within 24 hours of receipt. CD Laboratories (CLIA License# 21D0216863) is located in Baltimore, MD.
The Comprehensive Periprosthetic Joint Infection (PJI) panel includes:
- Synovasure® Alpha Defensin test
- Synovasure Neutrophil Elastase test
- Cell Count
Note: Tests are not currently available in the State of New York.
At this time, the Synovasure® Alpha Defensin test for PJI has only been validated for use with total joint replacements. To date, clinical studies to assess performance with partial joint replacements have not been conducted.
In the 158 patient study described in the Synovasure® white paper, 23% of patients had a concurrent diagnosis of an inflammatory condition. Concurrent inflammatory arthritis in patients did not affect the peformance of the Synovasure Alpha Defensin test, nor were the alpha defensin levels significantly different in this population.
First, a practice will need to obtain prior authorization (PA) from the patient’s insurance plan to perform the joint aspiration (arthrocentesis) and have the laboratory testing conducted by CD Laboratories. If approved, the PA number should be entered into the field on the Test Requisition Form. If PA cannot be obtained, the practice should seek alternative testing or have the patient determine whether to accept financial responsibility for the testing.
The physician will perform the joint aspiration (arthrocentesis) and bill the patient’s insurance plan as normal, using existing CPT® codes (e.g., 20610, 20611)*.
CD Laboratories will verify the patient’s insurance and PA information. Upon running the specimen, CD Laboratories will bill the patient’s insurance plan for the tests selected on the Test Requisition Form. If PA was denied and/or the patient accepted financial responsibility for the test, an invoice will be sent to the patient requesting payment.
If the arthrocentesis is being performed within a hospital (i.e., the patient is an inpatient or outpatient of a hospital), the hospital is required to bill Medicare for the test. CD Laboratories will serve as a reference laboratory in these scenarios and will bill the hospital for the services performed. Payment to the hospital will be based upon the applicable Medicare payment system for inpatient or outpatient services.
*Current Procedural Terminology (CPT®) copyright 2019 American Medical Association. All rights reserved. CPT is a registered trademark of the American Medical Association.
It is recommended that prior authorization (PA) be obtained from the patient’s insurance plan prior to the arthrocentesis and shipment of the specimen. The PA needs to specify that the laboratory test(s) will be performed by CD Laboratories. If approved, the PA number should be entered into the Test Requisition Form. CD Laboratories will bill the patient’s insurance upon performing the requested test(s). If the patient’s insurance plan declines coverage, the patient is responsible to cover the cost of the tests.
It is the patient’s responsibility to verify benefits before services are performed. Any questions regarding coverage should be directed to your insurance plan at the contact information listed on the back of the insurance card.
No, CD Laboratories does not know each patient’s insurance coverage. It is the patient’s responsibility to verify benefits before services are performed. Any questions regarding coverage should be directed to your insurance plan. Their contact information is listed on the back of your insurance card.
For information regarding coverage and benefits from your insurance plan, please contact your insurance plan directly. Their contact information is listed on the back of your insurance card. Information about how a specific claim is processed should be provided to you by your insurance plan on an Explanation of Benefits (EOB) form.
The invoice you received is for laboratory services provided by CD Laboratories, which were ordered by your physician. This invoice is for laboratory testing fees only and is separate from any bill you may have received from your physician and/or paid at your physician’s office. Please refer to the message on your CD Laboratories invoice or the EOB from your insurance plan for more specific information about why you received an invoice. A few reasons you may have received an invoice include, but are not limited to, the following:
- Insurance information was not received, or the wrong insurance information was received on your test order
- The insurance plan processed the claim and denied payment
- The insurance plan processed the claim and applied the balance to your co-pay or deductible
- The insurance plan did not respond to the claim
If you have additional questions or concerns, please contact your insurance plan directly. Their contact information is listed on the back of the patient’s insurance card.
If you would like further assistance, please call CD Laboratories’ Billing Department at (410) 296-1400, Option 3 or email your question to [email protected].