In addition, according to the imaging findings, PTB could be further divided into two types: severe PTB (including military tuberculosis and cavitary tuberculosis) and non-severe PTB (including infiltrative tuberculosis and tuberculous pleurisy), and 7 studies [16, 20, 21, 24–26, 29] compared the OPN levels in PTB patients with severe imaging presentations to those with non-severe findings, and the result showed that higher OPN levels were related to severe tuberculosis (SMD = 1.11, 95%CI = 0.90~1.33, P<0.001, I2 = 47%) (Fig 4). Here, SPP1 is linked to tuberculosis.