Comparative Yield of Tuberculosis during Active Case Finding Using GeneXpert or Smear Microscopy for Diagnostic Testing in Nepal: A Cross-Sectional Study

Abstract

This study compared the yield of tuberculosis (TB) active case finding (ACF) interventions applied under TB REACH funding. Between June 2017 to November 2018, Birat Nepal Medical Trust identified presumptive cases using simple verbal screening from three interventions: door-to-door screening of social contacts of known index cases, TB camps in remote areas, and screening for hospital out-patient department (OPD) attendees. Symptomatic individuals were then tested using smear microscopy or GeneXpert MTB/RIF as first diagnostic test. Yield rates were compared for each intervention and diagnostic method. We evaluated additional cases notified from ACF interventions by comparing case notifications of the intervention and control districts using standard TB REACH methodology. The project identified 1092 TB cases. The highest yield was obtained from OPD screening at hospitals (n = 566/1092; 52%). The proportion of positive tests using GeneXpert (5.5%, n = 859/15,637) was significantly higher than from microscopy testing 2% (n = 120/6309). (OR = 1.4; 95%CI = 1.12–1.72; p = 0.0026). The project achieved 29% additionality in case notifications in the intervention districts demonstrating that GeneXpert achieved substantially higher case-finding yields. Therefore, to increase national case notification for TB, Nepal should integrate OPD screening using GeneXpert testing in every district hospital and scale up of community-based ACF of TB patient contacts nationally.

Effectiveness of contact tracing in the control of infectious diseases: a systematic review

“…We screened 9050 unique abstracts, yielding 361 full-text articles to be assessed for eligibility, of which 314 were excluded. Of the 47 included articles evaluating contact tracing interventions, six were focused on COVID-19 20 , 21 , 22 , 23 , 24 , 25 ( table 1 ), 20 on tuberculosis 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ( table 2 ), eight on HIV 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ( appendix pp 11–14 ), 12 on curable STIs (syphilis, 54 , 55 , 56 gonorrhea, 57 , 58 , 59 , 60 trichomoniasis, 61 chlamydia, 62 , 63 and STI syndromes; 64 , 65 appendix pp 15–19 ), and one on measles 66 ( appendix p 20 ). Included studies were conducted across five continents ( appendix p 3 ), with study years ranging from 1975 to 2020.…”

“…The 47 studies comprised 18 (38·3%) randomised controlled trials (RCTs) 26 , 28 , 29 , 36 , 38 , 41 , 43 , 46 , 47 , 48 , 50 , 51 , 56 , 58 , 61 , 63 , 64 , 65 and 29 (61·7%) observational studies. 20 , 21 , 22 , 23 , 24 , 25 , 27 , 30 , 31 , 32 , 33 , 34 , 35 , 37 , 39 , 40 , 42 , 44 , 45 , 49 , 52 , 53 , 54 , 55 , 57 , 59 , 60 , 62 , 66 40 studies compared provider-initiated contact tracing with other interventions or evaluated expansions of provider-initiated contact tracing, 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 30 , 32 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ...…”

“…20 , 21 , 22 , 23 , 24 , 25 , 27 , 30 , 31 , 32 , 33 , 34 , 35 , 37 , 39 , 40 , 42 , 44 , 45 , 49 , 52 , 53 , 54 , 55 , 57 , 59 , 60 , 62 , 66 40 studies compared provider-initiated contact tracing with other interventions or evaluated expansions of provider-initiated contact tracing, 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 30 , 32 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 55 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 and seven studies compared programmatic adaptations within provider-initiated contact tracing. 29 ,…”

“…20 studies examined contact tracing for tuberculosis ( table 2 ). 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 These studies included more than 168 000 index patients across a diversity of settings, including urban and rural areas, high-burden and lower-burden areas (in terms of tuberculosis prevalence, incidence, or case notification rate), and all World Bank income levels ( appendix pp 9–10 ). A variety of tracing approaches were described between and within studies, including household contact tracing (17 of 20 studies) 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 36 , 38 , 39 , 40 , 41 , 42 , 43 , 45 and screenings of neighbours (three studies) 27 , 33 , 41 and co-workers (one study; 31 table 2 ).…”

“…Four of six RCTs and quasi-RCTs comparing contact tracing for tuberculosis to passive case finding or facility-based screening found an association between contact tracing and an increase in case detection 38 , 41 , 43 or decrease in incidence (when tracing was coupled with treatment for contacts with active disease and prophylaxis for contacts with latent infection); 28 whereas, the other two RCTs did not observe a positive effect on outcomes of interest 26 , 36 ( table 2 ). Among 11 observational studies comparing tracing programmes with control interventions, eight (72·7%) found an increase in tuberculosis case detection, 27 , 30 , 32 , 34 , 35 , 40 , 42 , 45 one (9·1%) identified an increase in cases averted, 44 one (9·1%) found a decrease in incidence, 37 and one (9·1%) found fewer cases detected with provider-initiated tracing than with patient-initiated tracing 39 ( table 2 ). Among these 17 studies overall, tracing for tuberculosis led to improved outcomes in lower-burden settings (three of three) 37 , 38 , 44 and high-burden settings (11 [78·6%] of 14 studies); 26 , 27 , 28 , 30 , 32 , 34 , 35 , 36 , 39 , 40 , 41 , 42 , 43 , 45 and in low-income countries (six of six) 30 , 34 , 35 , 41 , 42 , 45 and countries in other income categories (eight [72·7%] of 11 studies; 26 , 27 , 28 , 32 , 36 , 37 , 38 , 39 , 40 , 43 , 44 table 2 ,…”