Cost-Effectiveness of Latent Tuberculosis Screening Before Steroid Therapy for Idiopathic Nephrotic Syndrome in Children
Division of Nephrology, The Children's Hospital of Philadelphia, Philadelphia, PA.American Journal of Kidney Diseases (Impact Factor: 5.9). 07/2012; 61(1). DOI: 10.1053/j.ajkd.2012.06.004
BACKGROUND: Guidelines differ on screening recommendations for latent tuberculosis infection (LTBI) prior to immunosuppressive therapy. We aimed to determine the most cost-effective LTBI screening strategy before long-term steroid therapy in a child with new-onset idiopathic nephrotic syndrome. STUDY DESIGN: Markov state-transition model. SETTING & POPULATION: 5-year-old boy with new-onset idiopathic nephrotic syndrome. MODEL, PERSPECTIVE, & TIMEFRAME: The Markov model took a societal perspective over a lifetime horizon. INTERVENTION: 3 strategies were compared: universal tuberculin skin testing (TST), targeted screening using a risk-factor questionnaire, and no screening. A secondary model included the newer interferon γ release assays (IGRAs), requiring only one visit and having greater specificity than TST. OUTCOMES: Marginal cost-effectiveness ratios (2010 US dollars) with effectiveness measured as quality-adjusted life-years (QALYs). RESULTS: At an LTBI prevalence of 1.1% (the average US childhood prevalence in our base case), a no-screening strategy dominated ($2,201; 29.3356 QALYs) targeted screening ($2,218; 29.3356 QALYs) and universal TST ($2,481; 29.3347 QALYs). At a prevalence >10.3%, targeted screening with a risk-factor questionnaire was the most cost-effective option. Higher than a prevalence of 58.5%, universal TST was preferred. In the secondary model, targeted screening with a questionnaire followed by IGRA testing was cost-effective compared with no screening in the base case when the LTBI prevalence was >4.9%. LIMITATIONS: There is no established gold standard for the diagnosis of LTBI. Results of any modeling task are limited by the accuracy of available data. CONCLUSIONS: Prior to starting steroid therapy, only patients in areas with a high prevalence of LTBI will benefit from universal TST. As more evidence becomes available about the use of IGRA testing in children, the assay may become a component of cost-effective screening protocols in populations with a higher burden of LTBI.
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ABSTRACT: Bu çalışmada kullanılan hasta verilerinin bir kısmı, 4. Ulusal Viroloji Kongresi (23-26 Haziran 2011, İstanbul)'nde sunulmuştur. ÖZET Primer BK virus (BKV) enfeksiyonları genellikle erken çocukluk döneminde kazanılmakta ve asempto-matik olarak geçirilmektedir. Dünyadaki erişkin popülasyonlarda BKV seroprevalansı %90'a kadar ulaşa-bilir. Primer enfeksiyondan sonra virus ürogenital sistemde latent olarak kalmaktadır. Renal transplant alı-cılarında, BKV'nin neden olduğu primer enfeksiyonlar ve reaktivasyonlar, hastaların %10'unu etkileyebil-mekte ve önlem alınmadığı taktirde bu hastaların yarısından fazlası BKV nefropatisi (BKVN) nedeniyle böbreklerini kaybetmektedir. BKVN'ye bağlı greft kaybını engellemenin tek yolu, transplantasyon sonra-sında BK virus enfeksiyonlarının takibi ve BKVN geliştiren hastaların erken dönemde tanınıp etkin bir bi-çimde tedavi edilmeleridir. Bu çalışmada, pediatrik renal transplant alıcılarında, transplantasyon sonrası dönemde, idrar ve plazma örneklerinden, gerçek zamanlı polimeraz zincir reaksiyonu (rtPCR) ile BKV en-Geliş Tarihi (Received): 25.01.2013 • Kabul Ediliş Tarihi (Accepted): 20.03.2013 Özgün Çalışma/Original Article İletişim (Correspondence): Prof. Dr. Dilek Çolak, Akdeniz Üniversitesi Tıp Fakültesi, Tıbbi Mikrobiyoloji Anabilim Dalı, Viroloji Bilim Dalı, 07070, Arapsuyu, Antalya, Türkiye. Tel (Phone): +90 242 249 6405, E-posta (E-mail): email@example.com Mikrobiyol Bul 2013; 47(3): 461-471
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ABSTRACT: Primary BK virus (BKV) infections acquired mainly during childhood are usually asymptomatic. Several studies revealed its seroprevalence in adult population as high as 90% worldwide. Following primary infection, virus persists as latent infection in the urogenital tract. In renal transplant recipients, primary infection and reactivations affect 10% of patients and without treatment, more than half of these patients lose their grafts. The only way of preventing graft loss due to BKV nephropathy (BKVN), seems to monitor BKV infection after transplantation and to diagnose patients developing BKVN during the early period and treat them accordingly. In this study, we analyzed BKV presence in plasma and urine samples with real-time PCR method and evaluated the renal biopsies of pediatric renal transplant recipients after transplantation, retrospectively. A total of 142 children (63 female, 79 male; mean age: 11.7 ± 3.9 years) who had renal transplantation in Akdeniz University Medical Faculty, Antalya, Turkey, between February 2006 and April 2011 were enrolled in the study. After transplantation, peripheral blood and urine samples were collected bi-weekly for the first three months, monthly till the sixth month and every three months thereafter. BKV DNA was additionally screened in patients with unexplained rise in serum creatinine or in patients receiving anti-rejection therapy. In any plasma positivity or during the BKVN therapy, BKV DNA analysis was done bi-weekly. After DNA extraction by automated system, an 83 base pair fragment in VP1 region was amplified. Signal detection for the target region was performed with a TaqMan probe dual-labelled at the 5' end with 6-carboxyfluorescein (FAM) and the 3' end with 6-carboxytetramethylrhodamine (TAMRA). Histopathological examinations of renal biopsies were done with routine histological stains and immunohistochemical staining with monoclonal antibodies directed to SV40 antigen. From 2171 plasma and 1995 urine samples without PCR inhibitors, 442 (20%) (range: 300-4.5 x 10(7) copies/ml; mean: 2.0 x 10(5) ± 2.2 x 10(6) copies/ml) and 800 (40.1%) (range: 300-3 x 10(12) copies/ml; mean: 5.9 x 10(9) ± 1.1 x 10(11) copies/ml) were found positive for BKV DNA, respectively. For 114 (80.3%) patients, at least one urine sample was positive and more than half of those patients (68/114, 59.6%) had viremia. Of the patients, 19.7% (28/142) had viral DNA above 10(4) copies/ml, which was choosen as a cut-off value for its high positive predictive value for BKVN. For all these 28 patients, prior to renal biopsy, immunosupressive treatment was decreased. Cidofovir and/or leflunomid were initiated to nine patients who did not respond to lowered immunosupressive therapy and eight of them had renal biopsy for the confirmation of BKVN. All renal biopsy results were compatible with BKVN. From these nine patients who were receiving cidofovir and/or leflunomid, two lost their grafts because of BKVN. Since viruria is frequently encountered and the viral load is usually in low quantities and transient, it is more appropriate to use blood samples for screening programmes after renal transplantation. The efficacy of antiviral treatment in BKVN could not be evaluated since it was only applied in patients non-responding to lowered immunosuppressive therapy and had decreased renal functions. Multicenter prospective studies are required to enlighten this important issue. Early diagnosis with close monitoring of renal function and viremia, seems to be the most effective way for controlling BKVN.
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