Proportion Of Indeterminate Results Research Articles

Validation of the Hepamet fibrosis score in a multi-ethnic Asian population

Introduction and ObjectivesThe Hepamet fibrosis score was introduced for the diagnosis of advanced liver fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). To date, external validation is limited, and its utility in combination with liver stiffness measurement (LSM) has not been explored. Material and MethodsThis is a cross-sectional study on NAFLD patients who had a liver biopsy and LSM on the same day. The diagnostic performance of the Hepamet fibrosis score was evaluated using the area under the receiver operating characteristic curve (AUROC). ResultsThe data for 196 patients were analyzed (mean age 50 ± 11 years old, 50% men, 56.6% Malay, 27.6% Chinese, 15.8% Indian, 67.9% NASH, 15.8% advanced liver fibrosis). The AUROC of Hepamet fibrosis score for the diagnosis of advanced liver fibrosis was 0.85 (95% CI, 0.80 – 0.91). Using the <0.12 and ≥0.47 cut-offs from the original study, the sensitivity, specificity, positive predictive value, negative predictive value, the proportion of indeterminate results and misclassification rate were 81.8%, 91.8%, 47.4%, 98.2%, 32.1% and 6.1%, respectively. Using LSM <10 kPa and ≥15 kPa for the diagnosis of absence and presence of advanced liver fibrosis, respectively, in patients with Hepamet fibrosis score ≥0.47 (i.e., the two-step approach) reduced indeterminate results and misclassification to 16.1% and 3.6%, respectively. ConclusionsWe found the Hepamet fibrosis score to have good diagnostic accuracy in a population that was largely unrepresented in earlier work and demonstrated its utility in a two-step approach with LSM for the diagnosis of advanced liver fibrosis.

Comparison of diagnostic accuracy of QuantiFERON‐TB Gold Plus and T‐SPOT.TB in the diagnosis of active tuberculosis in febrile patients

ObjectiveThis study aimed to compare the accuracy of QuantiFERON‐TB Gold Plus (QFT‐Plus) and T‐SPOT.TB for diagnosing active tuberculosis (ATB) in febrile patients, to explore influencing factors of positive results and to verify the potential value of QFT‐Plus in the identification of ATB and latent tuberculosis infection (LTBI).MethodsA total of 240 febrile patients with ATB (n = 80) and non‐ATB (n = 160) were recruited to assess the accuracy of QFT‐Plus and T‐SPOT.TB for diagnosing ATB. Multivariable logistic regression was used to analyze the influencing factors of positive results.ResultsThe proportion of indeterminate results (ITRS) in QFT‐Plus and T‐SPOT.TB were 3.3% and 0%, respectively. The consistency between the results of the QFT‐Plus and T‐SPOT.TB was substantial. The area under the receiver operating characteristic curve (AUROC) of the QFT‐Plus and T‐SPOT.TB for diagnosing ATB was 0.792 and 0.849 (p = 0.070), respectively. The sensitivity of differentiating ATB from non‐ATB was 92.2% in QFT‐Plus versus 95.0% in T‐SPOT.TB. The influencing factors of T‐SPOT.TB positive result were male (odds ratio (OR) = 2.33, 95% confidence interval (CI) 1.27–4.26, p = 0.006), evidence of previous TB (OR 11.36, 95% CI 4.62–27.94, p < 0.001), while male (OR = 3.17, 95% CI 1.73–5.84, p < 0.001), evidence of previous TB (OR = 7.58, 95% CI 3.60–15.98, p <0.001), and use of immunosuppressant (OR = 0.49, 95% CI 0.260.94, p = 0.030) were influencing factors for QFT‐Plus positive result. There was no significant difference in QFT‐Plus in differentiating ATB from LTBI in febrile patients.ConclusionThere was no significant difference between QFT‐Plus and T‐SPOT.TB for diagnosing ATB in febrile patients. QFT‐Plus is prone to ITRS. The influencing factors including males, evidence of the previous TB, and use of immunosuppressant should be considered when interpreting positive results.

Extremes of age are associated with indeterminate QuantiFERON-TB gold assay results.

Results from 3,263 QuantiFERON-TB Gold in-tube (QFT-GIT) assays were analyzed to determine the impact of age on test performance. The proportion of indeterminate results was significantly higher in pediatric and elderly (9.1% and 7.4%, respectively) than in adult (2.6%; chi-square test, P < 0.0001) patients. A detailed analysis of indeterminate QFT-GIT assay results is presented.

Real-time PCR-assay in the delivery suite for determination of group B streptococcal colonization in a setting with risk-based antibiotic prophylaxis

Objective: Intrapartum antibiotic prophylaxis (IAP) reduces the incidence of neonatal early onset group B streptococcal infections. The present study investigated if an automated PCR-assay, used bedside by the labor ward personnel was manageable and could decrease the use of IAP in a setting with a risk-based IAP strategy.Methods: The study comprises two phases. Phase 1 was a multicenter, randomized, controlled trial. Women with selected risk-factors were allocated either to PCR-IAP (prophylaxis given if positive or indeterminate) or IAP. A vaginal/rectal swab and superficial swabs from the neonate for conventional culture were also obtained. Phase 2 was non-randomized, assessing an improved version of the assay.Results: Phase 1 included 112 women in the PCR-IAP group and 117 in the IAP group. Excluding indeterminate results, the assay showed a sensitivity of 89% and a specificity of 90%. In 44 % of the PCR assays the result was indeterminate. The use of IAP was lower in the PCR group (53 versus 92%). Phase 2 included 94 women. The proportion of indeterminate results was reduced (15%). The GBS colonization rate was 31%.Conclusion: The PCR assay, in the hands of labor ward personnel, can be useful for selection of women to which IAP should be offered.

Interferon-γ release assays for the diagnosis of tuberculosis and tuberculosis infection in HIV-infected adults: a systematic review and meta-analysis.

BackgroundDespite the widespread use of interferon-γ release assays (IGRAs), their role in diagnosing tuberculosis and targeting preventive therapy in HIV-infected patients remains unclear. We conducted a comprehensive systematic review to contribute to the evidence-based practice in HIV-infected people.Methodology/Principal FindingsWe searched MEDLINE, Cochrane, and Biomedicine databases to identify articles published between January 2005 and July 2011 that assessed QuantiFERON®-TB Gold In-Tube (QFT-GIT) and T-SPOT®.TB (T-SPOT.TB) in HIV-infected adults. We assessed their accuracy for the diagnosis of tuberculosis and incident active tuberculosis, and the proportion of indeterminate results. The search identified 38 evaluable studies covering a total of 6514 HIV-infected participants. The pooled sensitivity and specificity for tuberculosis were 61% and 72% for QFT-GIT, and 65% and 70% for T-SPOT.TB. The cumulative incidence of subsequent active tuberculosis was 8.3% for QFT-GIT and 10% for T-SPOT.TB in patients tested positive (one study each), and 0% for QFT-GIT (two studies) and T-SPOT.TB (one study) respectively in those tested negative. Pooled indeterminate rates were 8.2% for QFT-GIT and 5.9% for T-SPOT.TB. Rates were higher in high burden settings (12.0% for QFT-GIT and 7.7% for T-SPOT.TB) than in low-intermediate burden settings (3.9% for QFT-GIT and 4.3% for T-SPOT.TB). They were also higher in patients with CD4+ T-cell count <200 (11.6% for QFT-GIT and 11.4% for T-SPOT.TB) than in those with CD4+ T-cell count ≥200 (3.1% for QFT-GIT and 7.9% for T-SPOT.TB).Conclusions/SignificanceIGRAs have suboptimal accuracy for confirming or ruling out active tuberculosis disease in HIV-infected adults. While their predictive value for incident active tuberculosis is modest, a negative QFT-GIT implies a very low short- to medium-term risk. Identifying the factors associated with indeterminate results will help to optimize the use of IGRAs in clinical practice, particularly in resource-limited countries with a high prevalence of HIV-coinfection.

Interferon-gamma release assays for the diagnosis of active tuberculosis in HIV-infected patients: a systematic review and meta-analysis.

BackgroundInterferon-gamma release assays (IGRAs) have provided a new method for the diagnosis of Mycobacterium tuberculosis infection. However, the role of IGRAs for the diagnosis of active tuberculosis (TB), especially in HIV-infected patients remains unclear.MethodsWe searched PubMed, EMBASE and Cochrane databases to identify studies published in January 2001–July 2011 that evaluated the evidence of using QuantiFERON-TB Gold in-tube (QFT-GIT) and T-SPOT.TB (T-SPOT) on blood for the diagnosis of active TB in HIV-infected patients.ResultsThe search identified 16 eligible studies that included 2801 HIV-infected individuals (637 culture confirmed TB cases). The pooled sensitivity for the diagnosis of active TB was 76.7% (95%CI, 71.6–80.5%) and 77.4% (95%CI, 71.4–82.6%) for QFT-GIT and T-SPOT, respectively, while the specificity was 76.1% (95%CI, 74.0–78.0%) and 63.1% (95%CI, 57.6–68.3%) after excluding the indeterminate results. Studies conducted in low/middle income countries showed slightly lower sensitivity and specificity when compared to that in high-income countries. The proportion of indeterminate results was as high as 10% (95%CI, 8.8–11.3%) and 13.2% (95%CI, 10.6–16.0%) for QFT-GIT and T-SPOT, respectively.ConclusionIGRAs in their current formulations have limited accuracy in diagnosing active TB in HIV-infected patients, and should not be used alone to rule out or rule in active TB cases in HIV-infected patients. Further modification is needed to improve their accuracy.

Development of a molecular platform for HTLV confirmatory diagnosis: importance of the internal amplification control

Background Brazil may harbor the largest absolute number of HTLV-1-infected individuals worldwide. The current HTLV diagnosis is based mainly on antibodies detection. However, these tests exhibit high proportion of indeterminate results. Several real-time PCR techniques have been developed for the detection of HTLV-1/2. However, up to day the major drawbacks of HTLV-1/2 molecular diagnosis are the lack of standard molecular tests and the absence of suitable internal amplification control (IAC). The aim of this study was to develop a multiplex qualitative real-time PCR for the simultaneous detection and discrimination of HTLV-1/2 and to design an IAC for reaction monitoring. Methods After multiple sequence alignments of the full genomes of HTLV-1/2 subtypes, a conserved tax region was chosen for the design of specific primers and probes. The IAC was generated after the annealing of synthetic nucleotide sequences and cloned into TOPO TA ® vector. MT-2 and Gu cell lines were used as positive controls for HTLV-1 and HTLV-2, respectively. Results The developed multiplex real-time reaction detected both HTLV-1 and HTLV-2 (105 to 101 copies/reaction) at the presence of IAC in the same reaction. Analytical sensitivity was 1.2 copies/reaction for HTLV-1 and 19.1 copies/reaction for HTLV-2. The analytical sensitivity analysis was performed in singleplex format. Conclusion The detection of HTLV-1/2 and IAC by multiplex realtime PCR was efficient. The developed IAC is suitable for the molecular diagnosis and its presence ensures that the negative results are not due to failure in prePCR procedures.

Performance of the tuberculin skin test and interferon-γ release assay for detection of tuberculosis infection in immunocompromised patients in a BCG-vaccinated population

BackgroundInterferon-γ release assay (IGRA) may improve diagnostic accuracy for latent tuberculosis infection (LTBI). This study compared the performance of the tuberculin skin test (TST) with that of IGRA for the diagnosis of LTBI in immunocompromised patients in an intermediate TB burden country where BCG vaccination is mandatory.MethodsWe conducted a retrospective observational study of patients given the TST and an IGRA, the QuantiFERON-TB Gold In-Tube (QFT-IT), at Severance Hospital, a tertiary hospital in South Korea, from December 2006 to May 2009.ResultsOf 211 patients who underwent TST and QFT-IT testing, 117 (55%) were classified as immunocompromised. Significantly fewer immunocompromised than immunocompetent patients had positive TST results (10.3% vs. 27.7%, p 0.001), whereas the percentage of positive QFT-IT results was comparable for both groups (21.4% vs. 25.5%). However, indeterminate QFT-IT results were more frequent in immunocompromised than immunocompetent patients (21.4% vs. 9.6%, p 0.021). Agreement between the TST and QFT-IT was fair for the immunocompromised group (κ = 0.38), but moderate agreement was observed for the immunocompetent group (κ = 0.57). Indeterminate QFT-IT results were associated with anaemia, lymphocytopenia, hypoproteinemia, and hypoalbuminemia.ConclusionIn immunocompromised patients, the QFT-IT may be more sensitive than the TST for detection of LTBI, but it resulted in a considerable proportion of indeterminate results. Therefore, both tests may maximise the efficacy of screening for LTBI in immunocompromised patients.