According to the World Health Organization, tuberculosis continues to be one of the top ten leading causes of death around the world. The Tuberculin Skin Test (TST), developed in the early 1900s, has been the primary test for Tuberculosis (TB) screening throughout the world. Despite its long term use, the TST has long been known for having its limitations. One limitation is the high number of false positive results due to an interaction with Bacillus-Calmette-Guerrin (BCG) vaccine, reactions to non-tuberculosis mycobacterial infections and interpreter bias while reading the results. A second limitation is the need for two visits to obtain results. Compliance due to poor patient follow-up for skin test readings is especially problematic among high risk populations such as the homeless.
In 2006, a new blood test for TB screening called Interferon Gamma Release Assays (IGRA) was developed and identified by the Centers for Disease Control as an evidence based practice in screening for tuberculosis. The sensitivity of the IGRA test ranged from 76% to 90% compared to a TST which showed a sensitivity of 63% to 71%. A greater difference was demonstrated in the specificity of IGRA which ranged from 92% to 100% compared to the TST which ranged from 66% to 88%. As a result of the higher specificity, screening with an IGRA results in having fewer false positive results because there is no interpreter bias, no interaction with BCG and it does not respond to non-tuberculosis mycobacterial infections. This results in more accurate screening, clinical efficiencies and improved patient outcomes. Despite the research, adoption of IGRA for tuberculosis screening has been limited by a number of barriers including cost, lack of education of the new test and lack of nursing adoption.
Methods:
Promoting the transformation of knowledge and practice to advance global health and nursing is a critical component to ensuring evidence based screening for Tuberculosis. This presentation will report the evaluation of the implementation of IGRA in a large metropolitan public health department as evidence based practice for public health nursing. The ultimate goal was to improve secondary prevention screening for tuberculosis, create efficiencies and ensure better patient outcomes. The evaluation was made up of three components: a) usage of IGRA in the field, b) comparison of latent TB infection rates pre and post IGRA implementation with chi square analysis and c) cost analysis including an impact of cost for screening with TST and IGRA.
Results:
Usage of IGRA tests in the field setting were overall sucessful and showed a steady monthly inclined trend from 68 tests in January 2014 to 589 tests in the month of December 2014. Upon a more detailed review the results showed a trend of 5 sites who were slow to adopt the new evidence based practice. Barriers to implementation were primarily based on nursing staff knowldege, attitudes and behaviors and included: staff perception in safety of administering the test, lack of experience in venipuncture and refusal to change practice. The second component of the evaluation showed a statistically significant decrease (p<.0001) of Latent Tuberculosis Infection (LTBI) rates from 21.7% in 2012 where there was no use of IGRA compared to a 13.1% in 2014 when IGRA was implemented. This reduction in LTBI rates resulted in cost savings to the organization of $21,288 for every 1,000 contacts screened due to a reduction of persons needing chest x-ray and 9 month preventive treatment for LTBI.
Overall, the evaluation showed that adoption of evidence based practices can vary in different settings and barriers need to be identified and addressed in order to ensure compliance. TB infection rates decreased after IGRA implementation providing improved patient outcomes and cost effectiveness occurred during the screening process through a reduction of LTBI treatment as less false positives occurred.
Conclusion:
Evidence based practice is an essential component of improving nursing practice and improving patient outcomes. Despite it benefits, nurses have struggled to implement evidence based practices and an evaluation component proved critical to ensuring adoption of this practice across all settings. Implications for the nursing profession include the ability to effectively implement an evidence based practice that will screen patients with an evidence based test for tuberculosis and therefore ensure accurate results for improved patient outcomes.