Use of GeneXpert and the role of an expert panel in improving clinical diagnosis of smear-negative tuberculosis cases

PLoS One. 2019 Dec 30;14(12):e0227093. doi: 10.1371/journal.pone.0227093. eCollection 2019.

Abstract

Setting: A high proportion of notified tuberculosis cases in the Philippines are clinically diagnosed (63%) as opposed to bacteriologically confirmed. Better understanding of this phenomenon is required to improve tuberculosis control.

Objectives: To determine the percentage of smear negative presumptive tuberculosis patients that would be diagnosed by GeneXpert; compare clinical characteristics of patients diagnosed as tuberculosis cases; and review the impact that the current single government physician and a reconstituted Tuberculosis Diagnostic committee (expert panel) may have on tuberculosis over-diagnosis.

Design: This a cross-sectional study of 152 patients 15-85 years old with two negative Direct Sputum Smear Microscopy results, with abnormal chest X-ray who underwent GeneXpert testing and review by an expert panel.

Results: Thirty-two percent (48/152) of the sample were Xpert positive and 93% (97/104) of GeneXpert negatives were clinically diagnosed by a single physician. Typical symptoms and X-ray findings were higher in bacteriologically confirmed tuberculosis. When compared to the GeneXpert results the Expert panel's sensitivity for active tuberculosis was high (97.5%, 39/40), specificity was low (40.2%, 35/87).

Conclusion: Using the GeneXpert would increase the level of bacteriologically confirmed tuberculosis substantially among presumptive tuberculosis. An expert panel will greatly reduce over-diagnosis usually seen when a decision is made by a single physician.

Publication types

  • Comparative Study
  • Multicenter Study
  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Cross-Sectional Studies
  • DNA, Bacterial / isolation & purification*
  • Expert Testimony*
  • Feasibility Studies
  • Female
  • Humans
  • Lung / diagnostic imaging
  • Lung / microbiology
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis / genetics
  • Mycobacterium tuberculosis / isolation & purification*
  • Nucleic Acid Amplification Techniques / instrumentation*
  • Nucleic Acid Amplification Techniques / methods
  • Philippines
  • Pulmonologists
  • Radiography
  • Sputum / microbiology
  • Tuberculosis, Pulmonary / diagnosis*
  • Tuberculosis, Pulmonary / microbiology
  • Young Adult

Substances

  • DNA, Bacterial

Grants and funding

This study was part of a larger project called the Newton Agham Fund Impact Assessment of Diagnostic Algorithms and Tools for Multi Drug Resistant (MDR-TB) and Drug Sensitive Tuberculosis (TB) in the Philippines (TB-FIT) which was supported by the Philippine Council for Health Research and Development (PCHRD): Project Number FP160005 which the grant was awarded to CYY. More details on PCHRD can be seen on this link (pchrd.dost.gov.ph/index.php/programs-and-services/supported-projects?download=994:pchrdsupported-projects). All funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. There was no additional external funding received for this study.