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Fig. 2 | BMC Medicine

Fig. 2

From: Global variation in bacterial strains that cause tuberculosis disease: a systematic review and meta-analysis

Fig. 2

Variation in sampling methods of studies included in the systematic review. Variation in study design for the 206 studies that met the inclusion criteria for this systematic review. The proportion of studies in each country that collected a nationally representative sample versus a sample representative of a smaller geographic location are shown in purple and green, respectively. Light purple and green indicate the proportion of studies in each country that collected all reported or all new TB cases in a given location and time period. For the majority of studies, “all TB cases” represents culture-positive cases only; for studies that use GeneXpert remnants for DNA collection, this represents microscopy-positive cases. Dark purple and green indicate the proportion of studies in a given country that used a random or cluster-based survey sampling method to select a subset of cases. TB cases in each country were estimated by the Global Burden of Disease Study 2016 [40]. We calculated percent of all TB cases in each country using the total number of genotyped cases as the numerator and total estimated prevalent TB cases as the denominator. The radius of each pie is proportional to percent of total estimated TB cases that are represented across all studies in each country. Examples of percent of total estimated TB cases that correspond to pie sizes are shown in the legend in gray. The example pies show the minimum, mid-point, and maximum percent of estimated TB cases represented in this review

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