The effectiveness of contact investigation among contacts of tuberculosis patients: a systematic review and meta-analysis

Abstract

BackgroundWe aimed to evaluate the effectiveness of contact investigation in comparison to passive case-detection alone and estimated the yield of co-prevalent and incident tuberculosis (TB), and latent tuberculosis infection (LTBI) among contacts of patients with TB.MethodsA systematic search was undertaken of studies published between January 1, 2011 and October 1, 2019 in the English language. The proportion of contacts diagnosed with co-prevalent TB, incident TB and/or LTBI was estimated. Evaluation of the effectiveness of contact investigation included randomised trials, while the yield of contact investigation (co-prevalent and incident TB and LTBI) was assessed in non-randomised studies.ResultsData were extracted from 244 studies, of which 187 studies measured the proportion of contacts diagnosed with TB disease and 135 studies measured LTBI prevalence. Individual randomised trials demonstrated that contact investigation increased TB case notification (RR 2.5 [95% CI: 2.0–3.2]), TB case detection (OR 1.34 [95% CI: 0.43–4.24]) and decreased mortality (RR 0.6 [95% CI: 0.4–0.8]) and population TB prevalence (risk ratio 0.82 [95% CI: 0.64–1.04]).The overall pooled prevalence of TB was 3.6% (95% CI: 3.3–4.0%; I2=98.9%, 181 studies). The pooled prevalence of microbiologically-confirmed TB was 3.2% (95% CI: 2.6–3.7%; I2=99.5%, 106 studies). The pooled incidence of TB was highest in the first year after exposure to index patients (2.0%, 95% CI: 1.1–3.3%; I2=96.2%, 14 studies) and substantially lower five years after exposure to index patient (0.5%, 95% CI: 0.3–0.9%; 1 study). The pooled prevalence of LTBI among contacts was 42.4% (95% CI: 38.5–46.4%; I2=99.8%, 135 studies).Conclusions and RelevanceThis systematic review and meta-analysis found that contact investigation was effective in high-burden settings. The higher pooled prevalence estimates of microbiologically-confirmed TB compared to previous reviews suggests newer rapid molecular diagnostics contribute to increased case detection.

High proportion of tuberculosis transmission among social contacts in rural China: a 12-year prospective population-based genomic epidemiological study

“…A recent systematic review suggested that the pooled prevalence of TB in close contacts was 3•6% (95% CI: 3•3-4•0), and that contact investigation could increase TB case notification and thereby decrease the incidence of TB in the population. 18 In developed countries, index cases have been found to have 6-12 close contacts [19][20][21][22] who could potentially constitute 10-20% 23,24 of the total TB burden. Accordingly, the WHO strongly recommends systematic screening for TB disease among close contacts.…”

Estimating annual risk of infection with Mycobacterium tuberculosis – Authors’ reply

“…TST or IGRA positivity in this population is estimated to be 50•5%. 6 Of the remaining 49•5% of household contacts, an estimated 44% (254/576) remain persistently TST-negative or IGRA-negative. 7 83% of these individuals who are TST-negative or IGRA-negative were consistently negative on extended evaluation, 8 providing an estimated 20% prevalence of resistance.…”

Child Contact Case Management—A Major Policy-Practice Gap in High-Burden Countries

“…Systematic reviews that have assessed the prevalence of TB disease among contacts have consistently reported an increased risk of developing active TB disease in child contacts < 5 years of age. In addition, a meta-analysis of individual randomized trials demonstrated that contact investigation increased TB case notification (RR 2.5 [95% CI: 2.0-3.2]), and decreased mortality (RR 0.6 [95% CI: 0.4-0.8]) [5]. Despite supportive evidence and existing WHO and national-level recommendations for CCM, many barriers still exist to their implementation.…”