No abstract

Introduction: Cutaneous manifestations related to chronic kidney disease (CKD) are common and associated with high morbidity. Acquired perforating dermatosis (APD) occurs mostly in diabetic or CKD patients, namely those undergoing hemodialysis. Case report: A 58-year-old male with type 2 diabetes, with long-term insulin use, several microvascular and macrovascular complications, and on maintenance hemodialysis for 5 years presented with a 1-week history of painful, pruritic, umbilicated papules and some punctiform necrotic lesions on his left forearm, both hands, and both amputation stumps. There was no evidence of infection or vascular alterations, and the patient was not responsive to an initial course of topical corticosteroid. These lesions rapidly evolved to larger, coalescent necrotic injuries, with aggravated pain, intense left-hand skin peeling, and the appearance of similar lesions in the trunk, requiring hospital admission. Calciphylaxis and APD were suspected. Skin biopsy was performed and directed treatment initiated, including intradialytic sodium thiosulfate. Histology findings were compatible with APD and also excluded findings suggestive of vasculitis or calciphylaxis. Soon after, difficult-to-treat cellulitis of the left hand and forearm progressed to critical ischemia and amputation. Microbiology analysis revealed Serratia marcescens as the causative agent. Discussion: To our knowledge, there are no previously described cases of APD-related cellulitis. Its treatment can be particularly challenging, as lesions can persist and relapse, and chronic scars can develop. S. marcescens behaves as an opportunistic and difficult-to-treat pathogen, complicating the prognosis. Conclusion: APD can be associated with cellulitis and all of its complications in patients with underlying severe vasculopathy. Awareness of this complication in APD with early referral and aggressive treatment might improve the outcomes and quality of life of such patients.

Background and Aims Survival analysis is a cornerstone in medical research. For this purpose Kaplan-Meier is the most widely used statistical test, but the presence of competing risks violates the fundamental assumption that the censoring mechanism is independent of survival time. This leads to overestimation of the cumulative probability of cause-specific failure. Cumulative incidence estimate and competing risks analysis are preferred. The purpose of this study was to compare different survival analysis methods: Kaplan-Meier and cumulative incidence function estimates in a cohort of Peritoneal Dialysis (PD) patients. Method The survival of 115 incident patients on PD in a university hospital was evaluated after establishing 2 cohorts: patients starting renal replacement therapy with PD (PD first; n=85) and patients switching to PD on the first 6 months of dialysis (PD transfer; n=30). Kaplan-Meier, cumulative incidence function, cause-specific and subdistribution hazards were performed. The event of interest was death and the competing risk events were transfer to hemodialysis and renal transplantation. Results Besides higher residual renal function (RRF) and kt/V in the PD first group, there were no other significant differences between groups. There were 22 deaths. PD first group had a better survival with both Kaplan-Meier (log-rank test, p=0.013) and cumulative incidence function (p=0.021) approaches. The Cox regression model showed, as protecting variables, higher albumin (HR=0.174; CI95% 0.054-0.562), higher RRF (HR=0.785; CI95% 0.666-0.925) and PD first (HR=0.350; CI95% 0.132-0.927). Higher Charlson Index predicted worse outcome (HR=1.459; CI95% 1.159-1.835). PD as first dialysis therapy was associated with 65.0 % lower risk of death comparing with PD transfer. The subdistribution multivariable model found higher Charlson Index (HR=1.389; CI95% 1.118-1.725) and lower RRF (HR=0.798; CI95% 0.680-0.936) were statistically associated with death, but not PD transfer or albumin. This result differs from the obtained using the cause-specific hazard model. Analyzing the competing events, patients submitted to renal transplantation had a lower Charlson Index. Conclusion The probability of death was overestimated by the Kaplan-Meier method. The bias of Kaplan-Meier is especially great when the hazard of the competing risks is large. This study consisted on a statistical critical analysis of a real medical example, broader clinical conclusions related with “PD first initiative” should be cautious in this context. It is primordial to recognize the presence of competing risks in studies with multiple outcomes, as in Peritoneal Dialysis studies, to estimate cumulative incidence and yield more accurate results. This study shows how different conclusions are attained with different statistical methodology and its relevance in clinical context.

Background and Aims Peritoneal protein loss (PPL) in peritoneal effluent is a well-recognised detrimental result of peritoneal dialysis treatment since its inception. Hydrostatic convection is a major drive for peritoneal protein transport; therefore venous congestion may have a role in peritoneal protein loss (Krediet RT et al Perit Dial Int. 2019 ). The aim of this study was to explore the importance of overhydration on the magnitude of peritoneal protein clearance in incident PD patients. Method A total of 97 adult incident PD patients were included. A standard peritoneal equilibration test, 24-hour urine and dialysate collection, and multifrequency bioimpedance analysis were performed. Independent-samples t test and Pearson correlation coefficient were performed to evaluate relevant clinical associations and linear multivariable regression was done. Results Statistically significant univariable relationships for 24h PPL were found for continuous ambulatory PD technique (CAPD) and, with a correlation coefficient >0.20, for age, pulse pressure, 4-hour dialysate/plasma creatinine and extracellular water/total body water. On multivariable analysis, type of PD technique (β=0.327, p=0.011), 4-hour dialysate/plasma creatinine (β=0.247, p=0.037), and extracellular water/total body water (β=0.304, p=0.016) were significant independent predictors of peritoneal protein loss. Conclusion Overhydration revealed the most important connection with peritoneal protein loss. Mortality has been associated with PPL in some studies, but not others. This could be a result of this relationship, as volume overload has been strongly related with lower survival.

Background and Aims The report of peritoneal protein loss should be related with a timely collection (24-hour measurement or 4-hour PET assessment) or concentration. Standardized and reproducible estimation of peritoneal protein transport is obtained during PET. The 24-hour measurements estimate the real amount of PPL, but may be affected by other factors unrelated to the prognosis of PD patients, as inconsistencies in collection and management of the samples. Overall, PET protein loss quantification may be a more specific marker of peritoneal large-pore dysfunction and is seemingly more convenient than 24-hour measurements. The aim of this study was to compare the results of both sampling methods. Method A total of 144 adult incident PD patients were included. A standard peritoneal equilibration test, 24-hour urine and dialysate collection, and multifrequency bioimpedance analysis were performed. Independent-samples t test and Pearson correlation coefficient were performed to evaluate relevant clinical associations. Results Statistically significant univariable relationships for 24h PPL were found for continuous ambulatory PD technique (CAPD) and, with a correlation coefficient >0.20, for pulse pressure, 4-hour dialysate/plasma creatinine and extracellular water/total body water. Studying 240 min PPL, only with 4-hour dialysate/plasma creatinine, creatinine clearance and bicarbonate levels were statistically significant. In both samples there was no significant association with age, gender, type of effluent (biocompatible solutions or lactate plus bicarbonate comparing with bicarbonate), comorbidity Charlson Index, or presence of diabetes. Correlation between 240 min PPL and 24h PPL ensues, but it is not strong (p<0.001; r=0.365). Conclusion The weak correlation between 24h and 240 minutes show that these two measurements should not be considered equivalent. Measurements of a 24h sample might be more close to patients’ clinical status and prognosis, despite more frequent sampling errors. PET protein loss quantification should be regarded as a marker of peritoneal large-pore dysfunction.