Specificity of a whole blood IGRA in German nursing students

<p>Abstract</p> <p>Background</p> <p>Interferon-gamma release assays (IGRA) are used for tuberculosis (TB) screening in healthcare workers (HCWs). However, data on specificity of IGRA in serial testing of HCWs is sparse. Therefore the specificity and the negative predictive value of the IGRA - QuantiFERON-TB Gold In-Tube (QFT) - in German nursing students was investigated.</p> <p>Methods</p> <p>194 nursing students at the start of their professional career were tested with the QFT. 14 nursing students were excluded from the specificity analysis, due to exposure to mycobacterium tuberculosis. Two of these subjects were QFT- positive. None of them developed disease during the year of follow-up. A study group of 180 students, all with very low risk of prior TB infection, remained in the specificity analysis. Subjects were monitored for at least two years with respect to the development of active TB disease. IGRA was performed at the start of the training and after one year.</p> <p>Results</p> <p>The mean age of the study group (n = 180) was 23 years (range 18-53) with 70.9% female and 99.4% German born. The specificity of QFT was 98.9% (178/180; 95% CI 0.96-0.99); lowering the cut-off from 0.35 IU/ml to 0.1 IU/ml would have decreased specificity only slightly to 97.8% (176/180; 95% CI 0.94-0.99). Of the 154 nursing students available for re-testing, one student who initially scored positive reverted to negative, and one student initially negative converted to positive. None of the monitored group with initially negative QFT results developed TB disease, indicating a high negative predictive value of the IGRA in this population.</p> <p>Conclusions</p> <p>Following our data, QFT can serve as an effective tool in pre-employment TB screenings for HCWs. As its negative results were stable over time, specificity of the QFT in serial testing of HCWs is high. As the risk of acquiring TB infection in the German healthcare system appears to be low, our data supports the recommendation of performing TB screening only in those HCWs with known contact to TB patients or infectious materials.</p

Chronopsychobiologische Pilotstudie zur objektiven Bestimmung funktioneller Gesundheitszustände

1. Unterschiedliche Definitionen der Gesundheit mit verschiedenen Betrachtungsweisen (WHO: Der Mensch eine biopsychosoziale Einheit. Schulmedizin: ohne klinischen und paraklinischen Befund mit Orientierung an kritikbedürftigen Referenzmittelwerten) führt bei Fachleuten, Behörden und Laien zu Verwirrungen, wenn es um die Beurteilung gesundheitlicher Schäden geht. 2. Es wurde die Aufgabe gestellt zu prüfen, welche der beiden Definitionen der Realität näher kommt. 3. Mittels der chronopsychobiologischen Regulationsdiagnostik, des Dreiphasenentspannungstests (Hecht und Balzer 2001), wurden unter dem Aspekt der beiden Gesundheitsdefinitionen drei Gruppen untersucht (je 40 Probanden). - klinisch Gesunde (klinisch Gesunde nach Schulmedizin ) - Gesunde nach Definition der WHO - Probanden mit nichtorganische Insomnie (ohne pathologische klinische und paraklinische Befunde) 4. Die mit den verwendeten Methoden gewonnenen Daten wiesen aus, dass zwischen den klinisch Gesunden und den Probanden mit nichtorganischer Insomnie weitgehend größere Ähnlichkeiten bestehen. Beide Gruppen zeigten aber zu der Gruppe der Gesunden nach WHO-Definition, welche die biopsychosoziale Einheit des Menschen berücksichtigt, noch hochsignifikante Unterschiede. Die Gruppe der klinisch Gesunden kann daher auf Grund unserer Ergebnisse nicht den Anspruch erheben, real gesund zu sein. 5. Mit der Bezugnahme auf die Internationale Klassifikation der Krankheiten (ICD 10F) haben die von uns untersuchten klinisch Gesunden und die nichtorganischen Insomniker eine mehr oder weniger stark ausgeprägte Symptomatik von psychischen Störungen. Dies müsste bei der Beurteilung von Schadstoff-, Lärm-, und EMF-Wirkungen auf den Menschen, wie auch bei den klinisch-pharmakoloischen Untersuchungen beachtet werden. Die in der Arbeit erzielten Ergebnisse bedürfen durch weitere Untersuchungen eine Fundierung. Sie signalisieren aber sowohl unter praktischen als auch unter theoretischen Aspekten einen dringenden Forschungsbedarf.1. Differing definitions of health using different criterea (WHO: The human being as a bio- psycho-social unit versus classical medicine: without clinical and paraclinical results based on suspect reference values) bring confusion to experts, authorities and laymen when assessing health damages. 2. The given task was to check which of the two definitions is closer to reality. 3. Using the chrono-psycho-biological diagnostic of regulation, the three-phase-relaxation test (Hecht and Balzer 2001), three groups were examined considering the aspects of the two health definitions (40 test subjects in the study group). - clinically healthy (clinically healthy per classical medicine definition) - healthy per definition of the WHO - test persons with non organic insomnia (i.e. no pathological or paraclinical findings) 4. The data gained from the employed methods revealed bigger similarities between clinically healthy persons and those with non organic insomnia. Both groups still showed highly significant differences to the group which fulfils the definition of the WHO regarding a human as a bio-psycho-social unit. As a result of this study, persons, though classified as "clinically healthy" might nevertheless not absolutely be healthy in reality. 5. In reference to the international classification of illnesses (ICD 10 F) the groups examined, both of clinically healthy and those with non organic insomnia, have more or less severe psychological symptoms. This should be taken into account when assessing the effects of pollution, noise, and EMF as well as clinical pharmacological studies. These present findings still need broader confirmation by further investigations. However, they clearly indicate, for practical and theoretical considerations, an urgent need for further research