The impact of sputum quality on tuberculosis diagnosis: a systematic review

OBJECTIVE: To perform a systematic review to evaluate the impact of sputum quality on the yield of tuberculosis (TB) diagnostic tests. METHODS: We searched PubMed, EMBASE, LILACS and the Cochrane Database to identify studies that addressed 1) the impact of sputum quality on the proportion of sputum samples with Mycobacterium tuberculosis detected using smear, culture or polymerase chain reaction (PCR); and 2) the impact of pre-sputum collection interventions on sputum quality and M. tuberculosis detection. RESULTS: Ten studies met the eligibility criteria for review inclusion. Five studies assessed macroscopic and/or microscopic sputum quality characteristics and M. tuberculosis detection. The other five studies assessed the impact of pre-sputum collection interventions on sputum quality and M. tuberculosis detection. No studies assessed the impact of sputum quality on PCR-based diagnostic tests. CONCLUSION: Definitive conclusions about the utility of sputum quality assessments are limited by the paucity of, and heterogeneity within, the available data. Given the potential for sputum quality assessments to enhance diagnostic yield and prevent wasteful laboratory testing, further research into this field is urgently needed.