Explaining International Trends in Mortality on Hemodialysis Through Changes in Hemodialysis Practices in the Dialysis Outcomes and Practice Patterns Study (DOPPS).

RATIONALE & OBJECTIVE: Case-mix adjusted hemodialysis mortality has decreased since 1998. Many factors that influence mortality may have contributed to this trend and these associations may differ by continental region. We studied changes in hemodialysis facility practices over time and their potential role in mediating changes in patient survival. STUDY DESIGN: Observational prospective cohort study. SETTING & PARTICIPANTS: Adult hemodialysis patients treated in hemodialysis 500 facilities participating in the Dialysis Outcomes Practice Patterns Study (DOPPS) between 1999 and 2015 in the US, Japan, and 4 four European countries: Germany, Italy, Spain, and UK. PREDICTORS: Four practice measures at each facility: the percentages of patients with Kt/V>1.2, interdialytic weight gain [IDWG]<5.7%, phosphorus<6 mg/dL, and using AV fistulae. OUTCOMES: Patient survival. ANALYTICAL APPROACH: Mediation analyses, adjusted for case mix, were conducted using 3-year study phase as the exposure and facility practice measures as potential mediators. RESULTS: In Europe, we observed a 13% improvement in overall case-mix adjusted survival per decade. Trends in facility practice measures, especially Kt/V and phosphorus, explained 10% improvement in case-mix survival per decade, representing 77% (10% explained of 13% improvement) of the observed improvement. In Japan, 73% of the observed 12%/decade improvement in case-mix adjusted survival could be attributed to facility practices, especially Kt/V and IDWG. In the US, 56% of the observed 47%/decade improvement in case-mix adjusted survival could be attributed to facility practices, especially AV fistula use and phosphorus control. LIMITATIONS: Unmeasured changes in the characteristics of the patient population over this period may confound the observed associations. CONCLUSION: The improvements in adjusted hemodialysis patient survival in Europe, Japan, and the US from 1999 to 2015 can be largely explained by improvements in specific facility practices. Future changes in patient survival may be responsive to further evolution in the implementation of common clinical practices.

Symptom Burden and Its Impact on Quality of Life in Patients With Moderate to Severe CKD: The International Chronic Kidney Disease Outcomes and Practice Patterns Study (CKDopps).

RATIONALE & OBJECTIVE: Recent evidence suggests people with nondialysis chronic kidney disease (ND-CKD) experience a substantial burden of symptoms, but informative large-scale studies have been scarce. We assessed the prevalence of symptoms and the association of overall symptom burden with quality of life in patients with moderate to severe CKD. STUDY DESIGN: Cross-sectional study. SETTING & PARTICIPANTS: 4,430 patients with ND-CKD stages 3-5 enrolled in the Chronic Kidney Disease Outcomes and Practice Patterns Study (CKDopps) in Brazil, France, and the United States between 2013 and 2021. EXPOSURE: 13 individual patient-reported symptoms from the Kidney Disease Quality of Life Short Form (KDQOL-SF) questionnaire and an overall symptom burden score (low, intermediate, and high). OUTCOME: Physical and mental component summary scores (PCS and MCS) of the KDQOL-SF. ANALYTICAL APPROACH: Adjusted prevalence ratios and generalized estimating equations. RESULTS: Patients (mean age, 68 years; 40% women; mean baseline estimated glomerular filtration rate [eGFR], 30mL/min/1.73m2) were very much to extremely bothered by numerous symptoms ("soreness in muscles," 23%; "washed out or drained," 21%; "cramps, shortness of breath, dry skin, diminished sex life, or numbness in hands or feet," 14%-17%). The adjusted prevalences of "cramps," "washed out or drained," "lack of appetite," "nausea/upset stomach," and "sex life" were greater with more severe CKD and in women (except for "sex life"). A high overall symptom burden was more common in women, in France, and in patients with severe albuminuria and various comorbidities, but not with lower eGFR. The PCS and MCS scores were 13.4 and 7.7 points lower, respectively, for high versus low overall symptom burden. LIMITATIONS: Generalizability limited to patients under nephrology care, residual confounding, and inaccurate Brazilian translation of some symptoms. CONCLUSIONS: The high symptom burden observed in this large cohort of ND-CKD patients across 3 diverse countries and its strong association with poorer health-related quality of life should inform clinical management of and clinical research in CKD. PLAIN-LANGUAGE SUMMARY: Little is known about symptoms in patients with non-dialysis-dependent chronic kidney disease (ND-CKD). In the Chronic Kidney Disease Outcomes and Practice Patterns Study, which enrolled 4,430 patients with CKD stages 3-5 in Brazil, France, and the United States, patients most often reported soreness in muscles, feeling washed out or drained, cramps, shortness of breath, dry skin, altered sex life, and numbness in hands or feet. Cramps, feeling washed out or drained, lack of appetite, and nausea were more often reported at lower levels of kidney function. The overall symptom burden was higher in women than men, in French than in Brazilian or US patients, and in those with severe albuminuria. The higher the symptom burden, the lower were the physical and mental health quality of life scores. The high symptom burden observed in this large cohort of ND-CKD patients across 3 diverse countries and its strong association with poorer health-related quality of life should inform clinical management of and clinical research in CKD.

Risk factors of peritoneal dialysis-related peritonitis in the Japan Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS).

Background: Peritoneal dialysis (PD)-related peritonitis is a major complication of PD. Wide variations in peritonitis prevention, treatment strategies and consequences are seen between countries. These between-country differences may result from modifiable risk factors and clinical practices. Methods: A total of 1225 Japanese PD patients were included and prospectively followed in the Peritoneal Dialysis Outcomes and Practice Patterns Study phase 1 (2014-2018) and phase 2 (2018-2022). Associations between PD-related peritonitis and various risk factors were assessed by Cox proportional hazards survival models. Results: During follow-up (median 1.52 years), 539 peritonitis episodes were experienced by 364 patients. The country crude peritonitis rate was 0.27 episodes/patient-year. In the fully adjusted model, noticeable patient-level factors associated with experiencing any peritonitis included age {hazard ratio [HR] 1.07 per 5-year increase [95% confidence interval (CI) 1.01-1.14]}, serum albumin level [HR 0.63 per 1 g/dl higher (95% CI 0.48-0.82)] and continuous ambulatory peritoneal dialysis (PD) [HR 1.31 versus automated PD (95% CI 1.05-1.63)]. The adoption of antibiotic prophylaxis practice at the time of PD catheter insertion [HR 0.63 (95% CI 0.51-0.78)] or when having complicated dental procedures [HR 0.74 (95% CI 0.57-0.95)] or lower endoscopy [HR 0.69 (95% CI 0.54-0.89)] were associated with lower hazards of any peritonitis, while a routine facility practice of having more frequent regular medical visits was associated with a higher hazard. Conclusion: Identification of risk factors in Japan may be useful for developing future versions of guidelines and improving clinical practices in Japan. Investigation of country-level risk factors for PD-related peritonitis is useful for developing and implementing local peritonitis prevention and treatment strategies.

Characteristics of patients and facility of peritoneal dialysis in Korea: Results from the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS) Korea.

BACKGROUND: Varying peritoneal dialysis (PD)-related clinical outcomes have been reported in different countries. As a participant of the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS), this study investigated the characteristics of Korean PD patients, PD facilities and the incidence rates of clinical outcomes including mortality and PD-related outcomes. METHODS: From July 2019 to December 2021, a total of 766 Korean PD patients were included for analysis. Poisson regression analysis was used to explore the incidence rates of various clinical events including mortality, modality transfer, exit site or catheter tunnel infection and peritonitis. RESULTS: Among the 766 patients (median age 55.5 years, males 59.5%), 276 were incident and 490 were prevalent PD patients. The incidence rates of events were as follows: all-cause mortality (0.048), modality transfer (0.051), exit site or catheter tunnel infection (0.054) and peritonitis (0.136) events per person year. The most common causative organism for exit site or tunnel infection was staphylococcus species (47%) and that for peritonitis was streptococcus (28%) followed by staphylococcus (27%) species. CONCLUSIONS: Up to now, PDOPPS Korea has recruited 766 Korean PD patients and started documentation of major PD-related outcomes which occurred during the follow-up period. The overall incidence rates of clinical outcomes in Korean PD patients were relatively favourable. There was no statistically significant difference in the incidence rates of clinical outcomes according to both facility and patient factors.

International variations in serum PTH and calcium levels and their mortality associations in peritoneal dialysis patients: Results from PDOPPS.

BACKGROUND: Mineral bone disorder (MBD) in chronic kidney disease (CKD) is associated with high symptom burden, fractures, vascular calcification, cardiovascular disease and increased morbidity and mortality. CKD-MBD studies have been limited in peritoneal dialysis (PD) patients. Here, we describe calcium and parathyroid hormone (PTH) control, related treatments and mortality associations in PD patients. METHODS: We used data from eight countries (Australia and New Zealand (A/NZ), Canada, Japan, Thailand, South Korea, United Kingdom, United States (US)) participating in the prospective cohort Peritoneal Dialysis Outcomes and Practice Patterns Study (2014-2022) among patients receiving PD for >3 months. We analysed the association of baseline PTH and albumin-adjusted calcium (calciumAlb) with all-cause mortality using Cox regression, adjusted for potential confounders, including serum phosphorus and alkaline phosphatase. RESULTS: Mean age ranged from 54.6 years in South Korea to 63.5 years in Japan. PTH and serum calciumAlb were measured at baseline in 12,642 and 14,244 patients, respectively. Median PTH ranged from 161 (Japan) to 363 pg/mL (US); mean calciumAlb ranged from 9.1 (South Korea, US) to 9.8 mg/dL (A/NZ). The PTH/mortality relationship was U-shaped, with the lowest risk at PTH 300-599 pg/mL. Mortality was nearly 20% higher at serum calciumAlb 9.6+ mg/dL versus 8.4-<9.6 mg/dL. MBD therapy prescriptions varied substantially across countries. CONCLUSIONS: A large proportion of PD patients in this multi-national study have calcium and/or PTH levels in ranges associated with substantially higher mortality. These observations point to the need to substantially improve MBD management in PD to optimise patient outcomes. LAY SUMMARY: Chronic kidney disease-mineral bone disorder (MBD) is a systemic condition, common in dialysis patients, that results in abnormalities in parathyroid hormone (PTH), calcium, phosphorus and vitamin D metabolism. A large proportion of peritoneal dialysis (PD) patients in this current multi-national study had calcium and/or PTH levels in ranges associated with substantially higher risks of death. Our observational study design limits our ability to determine whether these abnormal calcium and PTH levels cause more death due to possible confounding that was not accounted for in our analysis. However, our findings, along with other recent work showing 48-75% higher risk of death for the one-third of PD patients having high phosphorus levels (>5.5 mg/dL), should raise strong concerns for a greater focus on improving MBD management in PD patients.

CKD-Associated Pruritus and Clinical Outcomes in Nondialysis CKD.

Rationale & Objective: Itching is a frequent symptom experienced by people with chronic kidney disease (CKD). We investigated the associations of CKD-associated pruritus (CKD-aP) with clinical outcomes. Study Design: This was a longitudinal cohort study. Setting & Participants: Patients from Brazil, France, and the United States enrolled in the Chronic Kidney Disease Outcomes and Practice Patterns Study (CKDopps) from 2013 to 2021, an international prospective cohort study of adults with nondialysis dependent CKD, and an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m2 were included. Exposure: CKD-aP was self-reported by response to the question: "During the past 4 weeks, to what extent were you bothered by itchy skin?" Outcomes: The outcomes were as follows: CKD progression, kidney replacement therapy (KRT) initiation, mortality, hospitalization, cardiovascular events, infection events. Analytical Approach: Associations with time-to-event outcomes were investigated using Cox proportional hazards models adjusted for potential confounders. Results: There were 4,410 patients from 91 clinics with a median age of 69 years and a median eGFR at patient questionnaire completion of 29 (21-38) mL/min/1.73 m2. The proportion of patients not at all, somewhat, moderately, very much, and extremely bothered by itchy skin was 49%, 27%, 13%, 7%, and 3%, respectively. Patients with more advanced stages of CKD, older age, and greater comorbidities reported to be more likely bothered by itchy skin. Among patients at least moderately bothered, 23% were prescribed at least 1 pharmacotherapy (35% in the United States, 19% in France, 4% in Brazil), including antihistamine (10%), gabapentin (6%), topical corticosteroids (4%), pregabalin (3%), or sedating antihistamine (3%). The HR (95% CI) for patients extremely (vs not at all) bothered was 1.74 (1.11-2.73) for all-cause mortality, 1.56 (1.11-2.18) for all-cause hospitalization, and 1.84 (1.22-2.75) for cardiovascular events. As CKD-aP severity increased, patients also had higher rates of infection events (P = 0.04); CKD-aP severity was not associated with KRT initiation (P = 0.20) or CKD progression (P = 0.87). Limitations: The limitations were 25% nonresponse rate, recall bias, and residual confounding factors. Conclusions: These results demonstrate a strong association between severe itch and clinical outcomes, providing the nephrology community new insights into the possible adverse consequences of CKD-aP in individuals with nondialysis CKD, and warrant further exploration. Plain-Language Summary: Chronic kidney disease-associated pruritus (CKD-aP) is a common disturbing symptom of chronic kidney disease (CKD). This article analyzes longitudinal data from the Chronic Kidney Disease Outcomes and Practice Patterns Study (CKDopps) to describe prevalence of CKD-aP in 4,410 individuals with nondialysis CKD, and its association with clinical outcomes. We found that 51% of the surveyed population were bothered by pruritus. CKD-aP was more prevalent in those with more advanced stages of CKD, older age, and with more comorbid conditions. Compared to those not at all bothered by pruritus, those who were extremely bothered had a higher risk of all-cause mortality, hospitalizations, and cardiovascular events. Severity of CKD-aP was not associated with CKD progression or initiation of kidney replacement therapy.

Pruritus in Hemodialysis Patients: Longitudinal Associations With Clinical and Patient-Reported Outcomes.

RATIONALE & OBJECTIVE: Cross-sectional studies have reported an association of chronic kidney disease-associated pruritus (CKD-aP) with adverse clinical events and patient-reported outcomes (PROs). We studied the longitudinal associations between changes in CKD-aP and clinical outcomes among patients receiving maintenance hemodialysis. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: 7,976 hemodialysis recipients across 21 countries in phases 4-6 (2009-2018) of the Dialysis Outcomes and Practice Patterns Study (DOPPS) who had 2 CKD-aP assessments approximately 12 months apart. EXPOSURES: Exposure status was based on the assessment of pruritis initially and again approximately 1 year later. Four groups were identified, including those with moderate or more severe pruritis only at the initial assessment (resolved), only at the second assessment (incident), at neither assessment (absent), or at both assessments (persistent). OUTCOMES: Laboratory values and PROs ascertained at the initial assessment of pruritis and 1 year later. ANALYTICAL APPROACH: Linear mixed model to investigate changes in laboratory values and PROs over the 1-year study period across the 4 exposure groups. RESULTS: 51% of patients had moderate to severe CKD-aP symptoms at either assessment (22% at both). The prevalences of depression, restless sleep, and feeling drained increased over the study period (+13%,+10%, and+14%, respectively) among patients with incident pruritus and decreased (-5%, -8%, and -12%, respectively) among patients with resolved pruritus. Minimal changes in PROs over time were observed for the absent and persistent groups. Changes over time in laboratory values (phosphorus, Kt/V) were not detected for either of these groups. Compared with patients with absent CKD-aP, the adjusted HRs for patients with persistent CKD-aP were 1.29 (95% CI, 1.09-1.53) for all-cause mortality, 1.17 (1.07-1.28) for all-cause hospitalization, and 1.48 (1.26-1.74) for cardiovascular events. LIMITATIONS: No interim evaluation of CKD-aP symptoms between the 2 assessments; potential selection bias from patients who died or were otherwise lost to follow-up before the second assessment. CONCLUSIONS: CKD-aP symptoms are chronic, and these findings highlight the potential value of repeated assessment of this symptom using standardized approaches. Future research should systematically investigate potential causes of CKD-aP and options for its effective treatment. PLAIN-LANGUAGE SUMMARY: Previous research has studied itching and its consequences in hemodialysis recipients only at a single time point. We surveyed 7,976 patients receiving maintenance hemodialysis to assess itching over a period of 1 year. We found that, among those experiencing itching at the initial assessment, more than half had persistent symptoms 1 year later. Those in whom itching developed during follow-up were more likely to experience depression, poor sleep, long recovery times after dialysis, and feeling faint or drained. These patients also rated their quality of life as poorer than those who did not experience itching. These findings emphasize the potential value of clinical detection of itching and the pursuit of effective treatments for patients receiving dialysis experiencing these symptoms.