Results Of 1326 records identified, 15 randomized clinical trials (N = 7122 patients) were included. Most trials assessed adding LAMA vs placebo or LAMA vs LABA to inhaled corticosteroids. Adding LAMA vs placebo to inhaled corticosteroids was associated with a significantly reduced risk of exacerbation requiring systemic corticosteroids (RR, [95% CI, to ]; RD, − [95% CI, − to ]). Compared with adding LABA, adding LAMA to inhaled corticosteroids was not associated with significant improvements in exacerbation risk (RR, [95% CI, to ]; RD, [95% CI, − to ]), or any other outcomes of interest. Triple therapy was not significantly associated with improved exacerbation risk vs inhaled corticosteroids and LABA (RR, [95% CI, to ]; RD, − [95% CI, − to ]).