Comparison of sputum collection methods for tuberculosis diagnosis: a systematic review and pairwise and network meta-analysisFindingsWe 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