Article Text

other Versions

Download PDFPDF
Original Article
Incremental value of T-SPOT.TB for diagnosis of active pulmonary tuberculosis in children in a high-burden setting: a multivariable analysis
  1. Daphne I Ling1,
  2. Mark P Nicol2,
  3. Madhukar Pai1,
  4. Sandra Pienaar3,
  5. Nandini Dendukuri4,
  6. Heather J Zar3
  1. 1Department of Epidemiology and Biostatistics, McGill University, Montreal, Quebec, Canada
  2. 2Division of Medical Microbiology and Institute for Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
  3. 3Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa
  4. 4Technology Assessment Unit, McGill University Health Centre, Montreal, Quebec, Canada
  1. Correspondence to Professor Heather J Zar, Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital, 5th Floor, ICH Building, Cape Town 7700, South Africa; heather.zar{at}uct.ac.za

Abstract

Introduction Interferon γ release assays (IGRAs) are increasingly used for tuberculosis (TB) infection, but their incremental value beyond patient demographics, clinical signs and conventional tests for active disease has not been evaluated in children.

Methods The incremental value of T-SPOT.TB was assessed in 491 smear-negative children from two hospitals in Cape Town, South Africa. Bayesian model averaging was used to select the optimal set of patient demographics and clinical signs for predicting culture-confirmed TB. The added value of T-SPOT.TB over and above patient characteristics and conventional tests was measured using statistics such as the difference in the area under the receiver operating characteristic curve (AUC), the net reclassification improvement (NRI) and the integrated discrimination improvement (IDI).

Results Cough longer than 2 weeks, fever longer than 2 weeks, night sweats, malaise, history of household contact and HIV status were the most important predictors of culture-confirmed TB. Binary T-SPOT.TB results did not have incremental value when added to the baseline model with clinical predictors, chest radiography and the tuberculin skin test. The AUC difference was 3% (95% CI 0% to 7%). Using risk cut-offs of <10%, 10–30% and >30%, the NRI was 7% (95% CI −8% to 31%) but the CI included the null value. The IDI was 3% (95% CI 0% to 11%), meaning that the average predicted probability across all possible cut-offs improved marginally by 3%.

Conclusions In a high-burden setting, the T-SPOT.TB did not have added value beyond clinical data and conventional tests for diagnosis of TB disease in smear-negative children.

  • Clinical Epidemiology
  • Tuberculosis

Statistics from Altmetric.com

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Linked Articles

  • Airwaves
    Andrew Bush Ian Pavord