While there was some variability, the studies were generally all "to the left" or "to the right" of the vertical odds ratio = 1 line.   That is, all but one (the Williamson article) were in the area of the graph associated with protection from antibiotics (odds ration < 1) for the outcomes of productive cough and clinical improvement at 7 to 11 days, and all were in the area associated with increased adverse effects for that outcome.  A measure of homogeneity was used, the chi-square statistic.  It revealed significant heterogeneity for the outcomes of productive cough and clinical improvement (p < 0.05), and homogeneity for the outcome of adverse drug effects (p > 0.05)