Long-term sonographic evaluation of the peritoneum in peritoneal dialysis patients: A retrospective cohort study

Abstract Background Long-term peritoneal dialysis (PD) causes morphological changes to the peritoneum. However, the sequential morphological changes of the peritoneum remain unclear due to the invasiveness and ethical dilemmas surrounding peritoneal biopsies. We aimed to evaluate these long-term morphological peritoneal changes using sonography, which was recently reported to be useful for morphological peritoneal evaluation. Methods We retrospectively identified 115 PD patients who underwent sonographic peritoneal membrane thickness (PMT) measurement. Univariate and multivariate linear regression analyses identified factors related to PMT at baseline (bPMT), at last measurement (lPMT), and the PMT change rate. Of the 115 patients, 42 patients had at least two PMT measurements, including a bPMT measurement. We evaluated the PMT change between bPMT and lPMT. We also evaluated the annual PMT change for 3 years before PD withdrawal in patients who discontinued PD due to peritoneal dysfunction. Clinical characteristics and parameters were analyzed according to PMT change rates (≤ 0 [n = 28] or > 0 [n = 20]). Results The mean age at PD introduction and mean PD duration were 63.7 ± 12.7 years and 40.5 ± 30.1 months, respectively. There was a significant positive correlation between the dialysate to plasma ratio of creatinine (D/P Cr) and lPMT (r = 0.386, p = 0.004), but not bPMT (r=-0.114, p = 0.326). In the multivariate analyses, D/P Cr remained an independent predictor of lPMT (r = 0.478, p = 0.001) after adjusting for age, sex, body mass index, PD duration, diabetes, and peritonitis rate. The mean bPMT and lPMT were 0.67 ± 0.15 mm and 0.69 ± 0.10 mm, respectively, without statistical difference (p = 0.49). Annual PMTs for 3 years before PD withdrawal were 0.67 ± 0.13 mm, 0.66 ± 0.11 mm, and 0.67 ± 0.08 mm, respectively, with no significant differences among measurements (p = 0.967). There were no differences in PD duration, the use of a dialysate containing over 2.5% glucose or icodextrin, and the peritonitis rate between groups divided by the PMT change rate. Conclusions PMT, measured by sonography, was positively correlated with peritoneal permeability. Repeated evaluation of the peritoneum by sonography will enable the recognition of transition in peritoneal function in real time and allow for more appropriate PD management. Furthermore, the peritoneum was not necessarily thickened regardless of PD duration or cause of withdrawal.