MUC1 and hypersensitivity pneumonitis: Two studies (20, 30) were included in the mixed group because they did not mention specific measurements and the findings indicated that the concentrations of KL-6 were much more elevated in patients suffering from HP in comparison to normal individuals (SMD = 3.62, 95% CI = 0.54-6.69, I2 = 89%, P = 0.02) (Table 3).