Browsing by Author "Al-Darraji, HA"

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    Diagnostic accuracy of the Xpert® MTB/RIF cycle threshold level to predict smear positivity: a meta-analysis
    Lange, B; Khan, P; Kalmambetova, G; Al-Darraji, HA; Alland, D; Antonenka, U; Brown, T; Balcells, ME; Blakemore, R; Denkinger, CM; Dheda, K; Hoffmann, H; Kadyrov, A; Lemaitre, N; Miller, MB; Nikolayevskyy, V; Ntinginya, EN; Ozkutuk, N; Palacios, JJ; Popowitch, EB; Porcel, JM; Teo, J; Theron, G; Kranzer, K
    SETTING: Xpert (R) MTB/RIF is the most widely used molecular assay for rapid diagnosis of tuberculosis (TB). The number of polymerase chain reaction cycles after which detectable product is generated (cycle threshold value, C-T) correlates with the bacillary burden. OBJECTIVE: To investigate the association between Xpert C-T values and smear status through a systematic review and individual-level data meta-analysis. DESIGN: Studies on the association between C-T values and smear status were included in a descriptive systematic review. Authors of studies including smear, culture and Xpert results were asked for individual-level data, and receiver operating characteristic curves were calculated. RESULTS: Of 918 citations, 10 were included in the descriptive systematic review. Fifteen data sets from studies potentially relevant for individual-level data meta-analysis provided individual-level data (7511 samples from 4447 patients); 1212 patients had positive Xpert results for at least one respiratory sample (1859 samples overall). ROC analysis revealed an area under the curve (AUC) of 0.85 (95%CI 0.82-0.87). Cut-off C-T values of 27.7 and 31.8 yielded sensitivities of 85% (95%CI 83-87) and 95% (95%C1 94-96) and specificities of 67% (95%CI 66-77) and 35% (95%CI 30-41) for smear-positive samples. CONCLUSION: Xpert CT values and smear status were strongly associated. However, diagnostic accuracy at set cut-off C-T values of 27.7 or 31.8 would not replace smear microscopy. How C-T values compare with smear microscopy in predicting infectiousness remains to be seen.