A clinical scoring system to prioritise investigation for tuberculosis among adults attending HIV clinics in South Africa

Yasmeen Hanifa, Katherine L. Fielding, Violet N. Chihota, Lungiswa Adonis, Salome Charalambous, Nicola Foster, Alan Karstaedt, Kerrigan McCarthy, Mark P. Nicol, Nontobeko T. Ndlovu, Edina Sinanovic, Faieza Sahid, Wendy Stevens, Anna Vassall, Gavin J. Churchyard, Alison D. Grant

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

Background: The World Health Organization (WHO) recommendation for regular tuberculosis (TB) screening of HIV-positive individuals with Xpert MTB/RIF as the first diagnostic test has major resource implications. Objective: To develop a diagnostic prediction model for TB, for symptomatic adults attending for routine HIV care, to prioritise TB investigation. Design: Cohort study exploring a TB testing algorithm. Setting: HIV clinics, South Africa. Participants: Representative sample of adult HIV clinic attendees; data from participants reporting ≥1 symptom on the WHO screening tool were split 50:50 to derive, then internally validate, a prediction model. Outcome: TB, defined as “confirmed” if Xpert MTB/RIF, line probe assay or M. tuberculosis culture were positive; and “clinical” if TB treatment started without microbiological confirmation, within six months of enrolment. Results: Overall, 79/2602 (3.0%) participants on ART fulfilled TB case definitions, compared to 65/ 906 (7.2%) pre-ART. Among 1133/3508 (32.3%) participants screening positive on the WHO tool, 1048 met inclusion criteria for this analysis: 52/515 (10.1%) in the derivation and 58/533 (10.9%) in the validation dataset had TB. Our final model comprised ART status (on ART > 3 months vs. pre-ART or ART < 3 months); body mass index (continuous); CD4 (continuous); number of WHO symptoms (1 vs. >1 symptom). We converted this to a clinical score, using clinically-relevant CD4 and BMI categories. A cut-off score of ≥3 identified those with TB with sensitivity and specificity of 91.8% and 34.3% respectively. If investigation was prioritised for individuals with score of ≥3, 68% (717/1048) symptomatic individuals would be tested, among whom the prevalence of TB would be 14.1% (101/717); 32% (331/ 1048) of tests would be avoided, but 3% (9/331) with TB would be missed amongst those not tested. Conclusion: Our clinical score may help prioritise TB investigation among symptomatic individuals.

Original languageEnglish
Article numbere0181519
JournalPLoS One
Volume12
Issue number8
DOIs
Publication statusPublished - 1 Aug 2017
Externally publishedYes

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