PTGS2 and peritonitis: However, patients who had peritonitis during the follow up period had higher PD effluent IL-6 level (26.6 ± 17.4 vs 15.1 ± 12.3 pg/ml, p = 0.037) and COX-2 level (4.97 ± 6.25 vs 1.60 ± 1.53 ng/ml, p = 0.007) after one year than patients without peritonitis (Fig. 2).