Understanding Flu Testing

Transcription

1 TECHNICAL BULLETIN Vol. 1 No. 2, August 2005 Understanding Flu Testing 1 Flu Facts 2 Choosing a Rapid Flu A+B Test 4 Improved Medical Outcomes 5 Enhanced Economic Value 8 9 BD Directigen EZ Flu A+B Technology: Two-step lateral flow process enhanced by proprietary reagents BD Directigen EZ Flu A+B Technology: Optimal readability

2 Flu Facts 1 The flu is a contagious respiratory illness caused by influenza viruses. Influenza A and B are the two types of influenza viruses that cause epidemic human disease. Influenza C usually causes mild upper respiratory tract disease and, as such, is not as important clinically. Influenza A viruses are further categorized into subtypes on the basis of two surface antigens: hemagglutinin (H) and neuraminidase (N). For example, H3N2 is the strain that has caused flu infections in recent years. In the U.S., more than 200,000 people are hospitalized each year from flu-related complications. 1 Approximately 36,000 people die from flu every year. 2 Flu-related costs are estimated to be anywhere from $12-20 billion annually. 3 High-risk populations for serious flu complications include: older adults young children those with certain health conditions, including pregnancy Diagnosis is most often determined clinically, based on symptoms during the appropriate time of year if disease is occurring in the community. Diagnostic tests are performed whenever diagnosis is uncertain and therapy is being considered. The FDA has cautioned healthcare professionals regarding the dangers of prescribing antiviral drugs for influenza based simply on clinical interpretation without a definitive flu diagnosis. 4 1 As reported at the CDC website: 2 The CDC MMWR report P1, May 28, 2004/Vol. 53/HR-6 3 Flu season could cost $20B. (2004, October 14). Retrieved from CNN website: 4 As reported at the FDA website: VOL. 1 NO. 2, AUGUST 2005

3 2 Choosing a Rapid Flu A+B Test There are currently several rapid Flu A+B tests available utilizing two major technologies, enzyme immunoassay (EIA) and chromatographic immunoassay (lateral flow). Each test type offers a wide range of performance and specimen choices. Key factors that each laboratory should be aware of when choosing a rapid Flu A+B test include: Test accuracy Ability to differentiate Flu A and Flu B Turnaround time Choices of specimen type Choices of transport medium Financial impact including reimbursement Reliable supply BD Diagnostics provides two choices for rapid Flu A+B testing: the BD Directigen Flu A+B test and the BD Directigen EZ Flu A+B test. BD Directigen Flu A+B Test Built on enzyme immunoassay technology. BD Directigen EZ Flu A+B Test Built on lateral flow technology. TECHNICAL BULLETIN

4 Choosing a Rapid Flu A+B Test (continued) 3 VOL. 1 NO. 2, AUGUST 2005

5 4 Improved Medical Outcomes The use of a rapid test kit with increased sensitivity can result in more accurate patient diagnosis. Improper diagnosis of influenza can lead to inappropriate use of antibiotics, lack of appropriate antiviral therapy and increased spread of influenza to high-risk patients and others in the community. In addition to being the first differentiated flu kit on the market, the high accuracy of the BD Directigen Flu A+B kit has made it the #1 rapid Flu A+B test used by hospital labs. As the innovator of lateral flow technology, BD is pleased to take flu testing to a new level of performance with the lateral flowbased BD Directigen EZ Flu A+B test. The BD Directigen EZ Flu A+B test ensures accurate and rapid results. As such, using this test benefits patients by enabling physicians to prescribe the most effective treatment in the most timely manner. TECHNICAL BULLETIN

6 Enhanced Economic Value 5 There are several financial aspects that should be considered when deciding on a Flu A+B kit: Financial impact related to reimbursement and regulatory considerations Financial impact to your laboratory Financial impact to patient care I. Financial Impact - Reimbursement Correct coding and subsequent reimbursement for any laboratory procedure, including influenza tests, can be a challenging process. Factors to be aware of when choosing a platform for influenza testing include: 1. CLIA Waived vs. Moderately Complex Tests 2. Non-differentiated vs. Differentiated Tests Tests that identify influenza, but cannot differentiate flu A and flu B may be reimbursed only once. Tests that differentiate flu A and flu B may be billed twice, only if separate test procedures are conducted with separate test results, and a physician specifically orders both tests. For differentiated tests: 3. Single Step vs. Multiple Step Tests For tests with a single step, an applicable single step code or the general methodology code (e.g., 87449, 87899) should be used. Reimbursement is less for single step tests due to reduced resource and time intensity. The multiple step CPT code applies to enzyme immunoassay (EIA) tests requiring multiple steps. Reflecting required resources, multiple step codes generally have higher reimbursements than single step codes. continued on page 6 VOL. 1 NO. 2, AUGUST 2005

7 6 Enhanced Economic Value (continued) 4. Single Test vs. Multiple Test Procedures If a single test procedure is used to differentiate between flu A and flu B, then the appropriate CPT code may be billed once. If separate tests are conducted to separately identify both flu A and flu B, and a physician specifically orders both tests, then the appropriate CPT code may be billed twice. II. Financial Impact - Your Laboratory A lot of time and many resource hours can be spent on validating specific transport media and specimen type requirements. Choosing a differentiated Flu A+B test with maximum flexibility in these areas can result in considerable savings in time and money for your laboratory. Transport Media The following transport media have been tested and found to be compatible with the BD Directigen EZ Flu A+B test*: Bartel ViraTrans Medium Cellmatics Earle s Minimal Essential Medium (EMEM) EMEM plus 0.5% BSA EMEM plus 1% BSA Hank s Basal Salt Solution M4 Medium M4 RT Medium M5 Medium Normal Saline** PBS plus 0.5% BSA PBS plus 0.5% gelatin Phosphate Buffered Saline (PBS) Starplex Multitrans Sucrose Phosphate (2-SP) Trypticase Soy Broth Trypticase Soy Broth + 0.5% gelatin Trypticase Soy Broth + 0.5% BSA Veal Infusion Broth (VIB) VIB plus 0.5% BSA BD Universal Viral Transport Medium * Other transport media may be utilized if an appropriate qualification exercise is performed. ** Frozen storage of specimens collected in normal saline is not recommended for testing with the BD Directigen EZ Flu A+B test. TECHNICAL BULLETIN

8 Enhanced Economic Value (continued) 7 III. Financial Impact - Patient Care Increasingly, more adults are being treated for the flu due to an increased availability of antiviral drugs. Common antiviral drugs for influenza fall into one of two categories: those that are influenza A specific, and those that treat both influenza A and B. The combined influenza A+B drugs (zanamivir and oseltamivir) are significantly more expensive than those that are influenza A specific (amantadine and rimantadine). The use of a differentiated flu test, which provides separate results for both flu A and flu B, enables the use of targeted antiviral therapies that treat specifically for either flu A or flu B. When using other flu tests that do not differentiate between flu A and flu B, treatment must rely on the more expensive broadspectrum antiviral drugs. Improper diagnosis of influenza can also result both in improper therapy as well as continued spread of the disease to high-risk patients and others in the community. 1 Costs are from on Costs are from on Cost is for a 30-tab packet 4 Cost is for a 60-tab packet 5 Cost is for 20 doses VOL. 1 NO. 2, AUGUST 2005

9 Tech_Bul_Flu.qxd 8 11/18/05 4:16 PM Page 10 BD Directigen EZ Flu A+B Technology: Two-step lateral flow process enhanced by proprietary reagents The BD Directigen EZ Flu A+B test utilizes a unique, patented form of lateral flow technology invented by BD. This technology enables a simpler workflow while providing maximum performance and easy readability. In order to detect all subtypes of influenza A strains and influenza B strains, rapid flu tests are typically designed to detect the influenza nucleoprotein. The nucleoprotein resides within the virus and is well conserved among subtypes. As a result, viral extraction is necessary to release the nucleoprotein and maximize detection. The BD Directigen EZ Flu A+B test utilizes a proprietary sample processing reagent specially developed to break down mucoid specimens for maximal antigen release (compare illustrations 1 and 2). Increased antigen release can allow for improved sensitivity. Illustration 1 Influenza antigen release without sample processing. Other lateral flow Flu A+B tests may lack the sample processing step or may require that mucoid samples be sonicated prior to testing. Illustration 2 Influenza antigen release after sample processing. TECHNICAL BULLETIN

10 BD Directigen EZ Flu A+B Technology: Optimal readability 9 The BD Directigen EZ Flu A+B test is designed for easy readability. Variations in test line intensity are typically seen with chromatographic (lateral flow) immunoassays. The sample processing reagent in the BD Directigen EZ Flu A+B test helps create a clear white to light pink background in the test result window. This allows for easier-to-read test lines. Optimized concentrations of antibodies and detector provide clearer test lines that are easier to read even with weak-positive samples. Some of the many benefits of the BD Directigen EZ Flu A+B test include great performance, increased laboratory efficiency and enhanced economic value. Great Performance: Analytical testing demonstrates ability to detect H5N1 isolates and the A/California/07/2004 strain High accuracy to ensure proper diagnosis: Flu A Flu B Accuracy* 95.5% 96.8% Increased Laboratory Efficiency: Single device for both flu A and flu B Proprietary reagent for making mucoid samples easy to test Easy-to-read test line for rapid result determination Results in only 15 minutes with simple-to-use workflow Convenient room temperature storage Enhanced Economic Value: Separate test wells for flu A and flu B allows for separate multi-step test reimbursement Compatible with a wide variety of transport media saving time and resources required for validation Liquid positive and negative controls assists with QC compliance Acceptable for use with multiple specimen types minimizing specimen incompatibility and rejection: Nasopharyngeal washes Nasopharyngeal aspirates Throat swabs * Accuracy based on nasopharyngeal wash and nasopharyngeal aspirate data. VOL. 1 NO. 2, AUGUST 2005

11 Featured in this bulletin: Cat. No. Quantity Description tests Directigen EZ Flu A+B Kit tests Directigen Flu A+B Kit Other BD Directigen Respiratory Testing Products: Cat. No. Quantity Description tests Directigen EZ RSV Kit tests Directigen RSV Kit tests Directigen RSV Kit tests Directigen EZ Group A Strep Kit BD Diagnostics 7 Loveton Circle Sparks, MD USA rue Aristide Bergès Le Pont de Claix, France Tel: Bristol Circle Oakville, Ontario Canada L6H 6R5 Tel: Tuas Avenue 2 Singapore Tel: Monte Pelvoux 111, 9th Floor Col. Lomas de Chapultepec México D.F. Tel: Rua Alexandre Dumas São Paulo, S.P. Brazil Tel: Akasaka DS Building 5-26 Akasaka 8-chome Minato-ku Tokyo, 107 Japan Tel: ViraTrans, Multitrans and Cellmatics are trademarks of Difco Laboratories, Inc., a subsidiary of Becton, Dickinson and Company. BD, BD Logo and all other trademarks are the property of Becton, Dickinson and Company BD August 2005 Printed in the USA