SPP1 and aneurysm: In the control patients with unruptured aneurysms, no gender differences were observed in plasma FL-OPN or OPN N-half levels (female:male = 469.35 ± 284.94:475.26 ± 308.56 pmol/L, p = 0.974; and 5.93 ± 7.65:7.30 ± 3.43 pmol/L, p = 0.732, respectively; unpaired t-test).