Table 1 summarizes their definitions for asthma exacerbation. Although these definitions varied, all 13 studies defined exacerbation based on increased corticosteroids or albuterol dose to control symptoms and/or the need for asthma-related emergency treatment/hospitalization. Fig 7 showed that anti-interleukin 5 monoclonal therapies were associated with a significant reduction in asthmatic exacerbation compared with placebo (RR = 0.66, 95% CI, 0.59–0.73, P<0.001), but the reporting was significantly heterogeneous (I2 = 51%, P<0.001, 95% CI 12% to 73%, HM2=1.05). This evidence concerns the gene IL5 and asthma.