Comparison of sputum collection methods for TB diagnosis: a systematic review and pairwise and network meta-analysis
Summary
Background
The performance of
laboratory tests to diagnose pulmonary tuberculosis is dependent
on the quality of the sputum sample tested. The relative merits
of sputum collection methods to improve tuberculosis diagnosis
are poorly characterised. We therefore aimed to investigate the
effects of sputum collection methods on tuberculosis diagnosis.
Methods
We did a systematic review
and meta-analysis to investigate whether non-invasive sputum
collection methods in people aged at least 12 years improve the
diagnostic performance of laboratory testing for pulmonary
tuberculosis. We searched PubMed, Google Scholar, ProQuest, Web
of Science, CINAHL, and Embase up to April 14, 2017, to identify
relevant experimental, case-control, or cohort studies. We
analysed data by pairwise meta-analyses with a random-effects
model and by network meta-analysis. All diagnostic performance
data were calculated at the sputum-sample level, except where
authors only reported data at the individual patient-level.
Heterogeneity was assessed, with potential causes identified by
logistic meta-regression.
Findings
We identified 23 eligible
studies published between 1959 and 2017, involving 8967
participants who provided 19 252 sputum samples. Brief,
on-demand spot sputum collection was the main reference
standard. Pooled sputum collection increased tuberculosis
diagnosis by microscopy (odds ratio [OR] 1·6, 95% CI
1·3–1·9, p<0·0001) or culture
(1·7, 1·2–2·4, p=0·01).
Providing instructions to the patient before sputum collection,
during observed collection, or together with physiotherapy
assistance increased diagnostic performance by microscopy (OR
1·6, 95% CI 1·3–2·0,
p<0·0001). Collecting early morning sputum did not
significantly increase diagnostic performance of microscopy (OR
1·5, 95% CI 0·9–2·6, p=0·2) or
culture (1·4, 0·9–2·4, p=0·2).
Network meta-analysis confirmed these findings, and revealed
that both pooled and instructed spot sputum collections were
similarly effective techniques for increasing the diagnostic
performance of microscopy.
Interpretation
Tuberculosis
diagnoses were substantially increased by either pooled
collection or by providing instruction on how to produce a
sputum sample taken at any time of the day. Both interventions
had a similar effect to that reported for the introduction of
new, expensive laboratory tests, and therefore warrant further
exploration in the drive to end the global tuberculosis
epidemic.
Funding
Wellcome Trust, Joint Global
Health Trials consortium, Innovation For Health and Development,
and Bill & Melinda Gates Foundation.
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Source:
The Lancet Global Health
