SPP1 and polycystic ovary syndrome: In PCOS subjects, LFC was higher in women with OPN levels in the second (6.6% vs 17.14% P = 0.002), third (6.6% vs 18.58% P < 0.001) and fourth quartiles (6.6% vs 12.59% P = 0.004, Fig. 2c) compared to those with OPN levels in the lowest quartile.