The fecal retention score assessed by plain abdominal radiography predicts the transition to hemodialysis in peritoneal dialysis patients

Constipation is a common symptom among patients with chronic kidney disease and is thought to be associated with factors such as diabetes, fluid restriction, dietary management limiting potassium and fiber, and use of medications that induce constipation. Constipation is defined as a condition involving changes in stool consistency and frequency, as well as difficulty defecating due to the retention of feces in the large intestine. The other symptoms include excessive straining, a sensation of incomplete defecation, and rectal or anal obstruction. Some studies define constipation as regular laxative use; however, this approach may lead to discrepancies since some individuals may experience symptoms without taking laxatives. Abdominal plain radiography is an easy and inexpensive imaging for evaluation of fecal accumulation and colonic obstruction. This study aims to determine if the degree of stool retention, as evaluated through routine abdominal radiography, correlates with the transition to hemodialysis in peritoneal dialysis patients.

This single-center cohort study included 45 patients undergoing peritoneal dialysis in 2020. Fecal retention was assessed using routine abdominal X-rays, in which the colon was divided into four quadrants—ascending, transverse, descending, and sigmoid/rectal—on a plain abdominal film. Each quadrant was scored as follows: 0 if stool occupied less than 50% of the lumen, and 1 if stool occupied more than 50%, yielding a total score ranging from 0 to 4. Patients were then categorized into two groups based on the median total score: the high score group (>2) and the low score group (≤2). The five-year clinical outcomes of transition to hemodialysis were calculated for each group using the Kaplan-Meier method, and adjusted hazard ratios were calculated using the Cox regression model. The study was performed in accordance with the Helsinki Declaration of 1975 as revised in 1983. All statistical tests were two-sided, and p < 0.05 was statistically significant.

There were no significant differences between the two groups in age, sex, dialysis vintage, history of peritonitis, and base-line biochemical parameters (hemoglobin, albumin, total cholesterol, urea nitrogen, calcium, phosphorus, alkaline phosphatase, C-reactive protein). The high-score group exhibited a higher prevalence of diabetes compared to the low-score group, and a significantly higher proportion of individuals within the high-score group were prescribed phosphate binders. During the 5-year observation period, 25 cases (55.6%) transitioned to hemodialysis, 3 cases were transferred to another hospital, 2 cases underwent kidney transplantation, and 1 case died. At the end of observation, 14 cases continued peritoneal dialysis. Patients with a high constipation score had a significantly shorter duration of peritoneal dialysis compared to those with a low score (log-rank test p < 0.05). This association remained significant after multivariate adjustment.

Constipation was identified as a risk factor for transition to hemodialysis in peritoneal dialysis patients. Plain abdominal radiography, a simple and cost-effective procedure, serves as a valuable diagnostic tool for constipation.