Constipation in chronic kidney disease: it is time to reconsider

Aberrant bowel movement frequencies coincide with increased microbe-derived blood metabolites associated with reduced organ function

Bowel movement frequency (BMF) directly impacts the gut microbiota and is linked to diseases like chronic kidney disease or dementia. In particular, prior work has shown that constipation is associated with an ecosystem-wide switch from fiber fermentation and short-chain fatty acid production to more detrimental protein fermentation and toxin production. Here, we analyze multi-omic data from generally healthy adults to see how BMF affects their molecular phenotypes, in a pre-disease context. Results show differential abundances of gut microbial genera, blood metabolites, and variation in lifestyle factors across BMF categories. These differences relate to inflammation, heart health, liver function, and kidney function. Causal mediation analysis indicates that the association between lower BMF and reduced kidney function is partially mediated by the microbially derived toxin 3-indoxyl sulfate (3-IS). This result, in a generally healthy context, suggests that the accumulation of microbiota-derived toxins associated with abnormal BMF precede organ damage and may be drivers of chronic, aging-related diseases.

Effects of Dietary Fiber Intake and the Prevalence of Constipation Among Patients With End-Stage Renal Disease (ESRD) in Jeddah, Saudi Arabia: A Cross-Sectional Observational Study

RATIONALE/BACKGROUND

Hemodialysis (HD) patients with end-stage renal disease (ESRD) are particularly prone to constipation, which has become a growing public health issue. Nutritional therapy, such as fiber intake, significantly influences the management of constipation. In Saudi Arabia, there is limited data on fiber consumption and its correlation with constipation management in HD patients.

AIMS

The study aimed to investigate the correlation between dietary fiber intake and its effect on the prevalence of constipation in HD patients.

MATERIALS AND METHODS

This cross-sectional observational study of 77 ESRD patients on HD aged 18+ was conducted in a single dialysis center over six months. A questionnaire was employed to diagnose constipation (as defined by the Rome IV criteria of constipation), and seven-day food records were used to evaluate dietary fiber intake.

RESULTS

A study found a high prevalence of constipation (53%) among participants, with a lower daily fiber intake than recommended. However, a significant relationship was found between fiber intake and constipation (p < 0.05) with lower fiber intake in constipated patients compared to non-constipated (p = 0.001).

CONCLUSION

The study highlights a significant link between fiber intake and constipation in HD patients, suggesting adequate daily intake of fiber was effective in preventing constipation and that nutritional counseling should include adequate daily fiber intake in medical therapy management.

Revitalizing the Gut Microbiome in Chronic Kidney Disease: A Comprehensive Exploration of the Therapeutic Potential of Physical Activity

Both physical inactivity and disruptions in the gut microbiome appear to be prevalent in patients with chronic kidney disease (CKD). Engaging in physical activity could present a novel nonpharmacological strategy for enhancing the gut microbiome and mitigating the adverse effects associated with microbial dysbiosis in individuals with CKD. This narrative review explores the underlying mechanisms through which physical activity may favorably modulate microbial health, either through direct impact on the gut or through interorgan crosstalk. Also, the development of microbial dysbiosis and its interplay with physical inactivity in patients with CKD are discussed. Mechanisms and interventions through which physical activity may restore gut homeostasis in individuals with CKD are explored.

Nursing management of catheter-related non-infectious complications of PD: Your questions answered

A review from the last seven years (August 2016-July 2023) of questions posted to the International Society for Peritoneal Dialysis (ISPD) website "Questions about PD" by nurses and physicians from around the world revealed that 19 of the questions were associated with optimal approaches for preventing, assessing, and managing issues related to PD catheter non-infectious complications. Our review focused on responses to these questions whereby existing best practice recommendations were considered, if available, relevant literature was cited and differences in international practices discussed. We combined similar questions, revised both the original questions and responses for clarity, as well as updated the references to these questions. PD catheter non-infectious complications can often be prevented or, with early detection, the potential severity of the complication can be minimized. We suggest that the PD nurse is key to educating the patient on PD about PD catheter non-infectious complications, promptly recognize a specific complication and bring that complication to the attention of the Home Dialysis Team. The questions posted to the ISPD website highlight the need for more education and resources for PD nurses worldwide on the important topic of non-infectious complications related to PD catheters, thereby enabling us to prevent such complications as PD catheter malfunction, peri-catheter leakage and infusion or drain pain, as well as recognize and resolve these issues promptly when they do arise, thus allowing patients to extend their time on PD therapy and enhance their quality of life whilst on PD.

Real-world evidence of constipation and laxative use in the Korean population with chronic kidney disease from a common data model

Constipation is a highly prevalent gastrointestinal disorder in patients with chronic kidney disease (CKD). However, our understanding of its epidemiology and management in CKD is limited. We aimed to explore real-world data on constipation and laxative use in patients with CKD in a nationwide population-based cohort from the Korean Health Insurance Review and Assessment-National Patient Sample database. This study analyzed retrospective health claims data in Korea from 2012 to 2017 that were transformed into the Observational Medical Outcomes Partnership Common Data Model. The pooled proportion of constipation diagnoses was 30.5% in all patients with CKD and 15.9%, 16.5%, 17.4%, 29.9%, and 43.3% in patients with CKD stages 1-5, respectively, suggesting a higher prevalence in advanced CKD. Patients receiving peritoneal dialysis or hemodialysis had the highest prevalence of constipation, while transplant recipients showed a prevalence comparable to that of patients with early CKD. Patients with CKD had a significantly higher risk of constipation than age- and sex-matched non-CKD individuals (range of odds ratio [OR]:1.66-1.90). Laxative prescribing patterns differed by CKD severity. Osmotic agents were prescribed in more than half of patients with advanced CKD, while magnesium salts and bulking agents were prescribed less frequently. The CKD patients with constipation were more likely to be prescribed constipation-inducing medications, including antipsychotic and neurological medications. Our findings provide real-world constipation and laxative prescription status in the Korean CKD population, revealing a significantly higher risk of constipation and different laxative prescribing patterns in patients with CKD.

Generally-healthy individuals with aberrant bowel movement frequencies show enrichment for microbially-derived blood metabolites associated with reduced kidney function

Bowel movement frequency (BMF) has been linked to changes in the composition of the human gut microbiome and to many chronic conditions, like metabolic disorders, neurodegenerative diseases, chronic kidney disease (CKD), and other intestinal pathologies like irritable bowel syndrome and inflammatory bowel disease. Lower BMF (constipation) can lead to compromised intestinal barrier integrity and a switch from saccharolytic to proteolytic fermentation within the microbiota, giving rise to microbially-derived toxins that may make their way into circulation and cause damage to organ systems. However, the connections between BMF, gut microbial metabolism, and the early-stage development and progression of chronic disease remain underexplored. Here, we examined the phenotypic impact of BMF variation in a cohort of generally-healthy, community dwelling adults with detailed clinical, lifestyle, and multi-omic data. We showed significant differences in microbially-derived blood plasma metabolites, gut bacterial genera, clinical chemistries, and lifestyle factors across BMF groups that have been linked to inflammation, cardiometabolic health, liver function, and CKD severity and progression. We found that the higher plasma levels of 3-indoxyl sulfate (3-IS), a microbially-derived metabolite associated with constipation, was in turn negatively associated with estimated glomerular filtration rate (eGFR), a measure of kidney function. Causal mediation analysis revealed that the effect of BMF on eGFR was significantly mediated by 3-IS. Finally, we identify self-reported diet, lifestyle, and psychological factors associated with BMF variation, which indicate several common-sense strategies for mitigating constipation and diarrhea. Overall, we suggest that aberrant BMF is an underappreciated risk factor in the development of chronic diseases, even in otherwise healthy populations.

Effects of Polydextrose Supplementation on Intestinal Function in Hemodialysis Patients: A Double-Blind, Randomized, Placebo-Controlled Trial

OBJECTIVES

Intestinal constipation is a frequent complication in hemodialysis (HD) patients. Polydextrose (PDX), a nondigestible oligosaccharide, has been reported as a fermentable fiber with potential benefits. This study aimed to investigate the possible influence of PDX supplementation on intestinal function in HD patients.

METHODS

This randomized, double-blind, placebo-controlled trial included 28 patients who received daily oral supplementation with 12 g of PDX or placebo (corn starch) for 2 months. ROME IV criteria were used to define constipation and questionnaires were applied to patient assessment of constipation symptoms (PAC-SYM) and their impact on the patient assessment of constipation quality of life. The Bristol scale was used to assess stool consistency. Commercial Enzyme-Linked Immuno Sorbent Assay kits were used to evaluate the interleukin-6 and tumor necrosis factor-α plasma levels.

RESULTS

25 patients completed the study; 16 in the PDX group [7 females, 48.5 years (IQR = 15.5)] and 9 in the control group [3 females, 44.0 years (IQR = 6.0)]. According to ROME IV criteria, 55% of patients were diagnosed with constipation. PAC-SYM faecal symptoms domain was reduced after 2 months of PDX supplementation (P = .004). We also observed a significant reduction in the PAC-QoL-concerns domain (P = .02). The average values for PAC-SYM and patient assessment of constipation quality of lifewere reduced significantly after intervention with PDX. There were no significant changes after the intervention period concerning biochemical variables, food intake, and inflammation markers. No adverse effects were observed during the supplementation period.

CONCLUSIONS

The results of the present study suggest that short-term PDX supplementation may have favourable results on intestinal function and the quality of life of chronic kidney disease patients in HD.

Randomized Study of Tenapanor Added to Phosphate Binders for Patients With Refractory Hyperphosphatemia

Introduction

Serum phosphorus management is important for patients with chronic kidney disease on dialysis to reduce the risk of hyperparathyroidism and ectopic vascular calcification. Phosphate binders (PBs) control serum phosphorus levels; however, some patients do not achieve adequate control with existing PBs. The similar mechanisms of action of each PB may limit their ability to lower serum phosphorus levels. Therefore, drugs with novel mechanisms of action that can be added to existing PBs to further lower serum phosphorus levels are desired. Tenapanor, a novel selective inhibitor of intestinal sodium/hydrogen exchanger 3 transporters, decreases passive phosphate absorption in the intestine, thereby decreasing serum phosphorus levels.

Methods

This study evaluated the efficacy and safety of tenapanor treatment with up-titration when added to PBs among Japanese hemodialysis patients with hyperphosphatemia poorly controlled by PBs alone. In total, 169 patients taking PBs whose serum phosphorus level was ≥6.1 and <10.0 mg/dl initiated the 8-week treatment (placebo + PB, n = 85; tenapanor + PB, n = 84).

Results

The least squares mean change from baseline to week 8 in serum phosphorus level was -0.24 and -2.00 mg/dl in the placebo and tenapanor groups, respectively, with a statistically significant difference between groups (-1.76 mg/dl; P < 0.0001). Diarrhea as a treatment-emergent adverse event (TEAE) occurred in 14.1% and 63.1% of patients in the placebo and tenapanor groups, respectively. All diarrhea events were mild or moderate.

Conclusion

Tenapanor added to PBs improved serum phosphorus levels that could not previously be controlled by PBs alone, and no new safety concerns were raised.

Constipation in Patients With Chronic Kidney Disease

Constipation is a frequent symptom in patients with chronic kidney disease (CKD). This review outlines the mechanisms and management of constipation in patients with CKD from a physician's perspective. Common causes of constipation in patients with CKD include concomitant medications, low dietary fiber intake, water-restricted diet, lack of physical activity, altered gut microbiota, and reduced gastrointestinal motility. Constipation has a negative impact on overall health, and, in particular, the presence of constipation has been associated with worsening kidney function and increased risk of developing advanced stages of CKD. Although lifestyle and dietary modifications may not always be practical for patients with CKD, they are recommended because they are beneficial as they lower mortality in patients with CKD. The use of laxatives containing magnesium salts, bulking agents, and osmotic laxatives may have insufficient efficacy and may be associated with adverse effects. In contrast, lactulose and lubiprostone have been shown to exhibit reno-protective effects. Linaclotide and plecanatide have very limited systemic absorption and appear safe in patients with CKD. Tenapanor reduces paracellular intestinal phosphate absorption in addition to blocking sodium uptake by enterocytes, and provides additional benefit in patients patients with CKD who have hyperphosphatemia and constipation. Prucalopride leads to improvements in bowel function and constipation-related symptoms in cases in which response to conventional laxatives are inadequate. However, the dose of prucalopride should be reduced to 1 mg once daily for patients with CKD. In conclusion, there are important advances on the impact and treatment of constipation in patients with CKD.

Clinical Perspectives of Gut Microbiota in Patients with Chronic Kidney Disease and End-Stage Kidney Disease: Where Do We Stand?

The gut microbiota (GM) plays a vital role in human health, with increasing evidence linking its imbalance to chronic kidney disease and end-stage kidney disease. Although the exact methods underlying kidney-GM crosstalk are not fully understood, interventions targeting GM were made and lay in three aspects: diagnostic, predictive, and therapeutic interventions. While these interventions show promising results in reducing uremic toxins and inflammation, challenges remain in the form of patient-specific GM variability, potential side effects, and safety concerns. Our understanding of GMs role in kidney disease is still evolving, necessitating further research to elucidate the causal relationship and mechanistic interactions. Personalized interventions focusing on specific GM signatures could enhance patient outcomes. However, comprehensive clinical trials are needed to validate these approaches' safety, efficacy, and feasibility.

The effects of synbiotics on indoxyl sulphate level, constipation, and quality of life associated with constipation in chronic haemodialysis patients: a randomized controlled trial

Background

Gut microbiota dysbiosis in patients with chronic kidney disease on haemodialysis (CKD-HD) creates an increase in proteolytic bacteria activity, leading to an increase in the production of uraemic toxins, such as indoxyl sulphate, worsening of constipation symptoms and reducing patients’ quality of life. Improving gut microbiota dysbiosis is expected to improve this condition. This study aimed to evaluate the effect of synbiotics on indoxyl sulphate levels, constipation symptoms, and constipation-related quality of life in haemodialysis patients.

Methods

This was a double-blinded randomized controlled clinical trial with a parallel design involving haemodialysis patients. We included chronic haemodialysis patients with gastrointestinal complaints, difficulty defecating, faeces with hard consistency, or a bowel movement frequency of fewer than three times per week. Patients were randomly divided into two groups (synbiotics (Lactobacillus acidophilus and Bifidobacterium longum 5x10⁹ CFU) and placebo) for 60 days of oral intervention. All participants, caregivers, and outcome assessors were blinded to group assignment. The primary outcome was a decrease in indoxyl sulphate toxin levels. Meanwhile, improvement in constipation symptoms (measured using the Patient Assessment of Constipation: Symptoms (PAC-SYM) questionnaire) and improvement in constipation-related quality of life (measured using the Patient Assessment of Constipation Quality of Life (PAC-QOL) questionnaire) were assessed as secondary outcomes.

Results

We included 60 patients (30 intervention; median age of 51.23 (13.57) years, 33.3% male; 30 control; median age of 52.33 (11.29) years, 36.7% male). There was no significant difference in terms of pre- and postintervention indoxyl sulphate toxin levels in the synbiotics group compared to the placebo group (p=0.438). This study found an improvement in constipation symptoms (p = 0.006) and constipation-related quality of life (p=0.001) after synbiotic administration.

Conclusion

Two months of synbiotic supplementation did not lower indoxyl sulphate toxin levels. Nevertheless, it had a major effect in improving constipation and quality of life affected by constipation in patients undergoing chronic haemodialysis.

Trial registration

NCT04527640 (date of first registration: 26/08/2020)

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02890-9.

Personalizing Medication Recommendation with a Graph-Based Approach

The broad adoption of electronic health records (EHRs) has led to vast amounts of data being accumulated on a patient’s history, diagnosis, prescriptions, and lab tests. Advances in recommender technologies have the potential to utilize this information to help doctors personalize the prescribed medications. However, existing medication recommendation systems have yet to make use of all these information sources in a seamless manner, and they do not provide a justification on why a particular medication is recommended. In this work, we design a two-stage personalized medication recommender system called PREMIER that incorporates information from the EHR. We utilize the various weights in the system to compute the contributions from the information sources for the recommended medications. Our system models the drug interaction from an external drug database and the drug co-occurrence from the EHR as graphs. Experiment results on MIMIC-III and a proprietary outpatient dataset show that PREMIER outperforms state-of-the-art medication recommendation systems while achieving the best tradeoff between accuracy and drug-drug interaction. Case studies demonstrate that the justifications provided by PREMIER are appropriate and aligned to clinical practices.

Survey of defecation habits in apparently healthy and chronic kidney disease cats

OBJECTIVES

Changes in bowel movements (BMs) are an important clinical sign in many diseases, including chronic kidney disease (CKD), and the purpose of this study was to collect information on BMs and fecal scores in both apparently healthy and CKD cats. A secondary aim was to assess owner awareness of BM frequency.

METHODS

Owners were asked to complete an initial online questionnaire about their cat's health and litter box habits (including predicted BM frequency and fecal scores) and were then asked to clean the box daily for 7 days and report results (observed frequency of BMs and fecal scores) daily. Differences in BM frequency and fecal scores between apparently normal and CKD cats were compared using the Mann-Whitney test, and predicted vs observed data were compared using the Wilcoxon signed rank test. Difference in percentage of cats defecating more or less than once daily were assessed with Fisher's exact test.

RESULTS

Survey data from 124 owners of apparently healthy cats and 43 owners of CKD cats who submitted two or more days of daily observations (in addition to the initial questionnaire) were analyzed. Eighty-five percent of apparently healthy cats were observed to defecate one or more times per day and 15% defecated less than once per day. Fifty-eight percent of CKD cats defecated one or more times per day and 42% defecated less than once per day. A significantly higher percentage of CKD cats defecated less than once per day in comparison with apparently healthy cats (P <0.0001). Observed BM frequency was significantly less in CKD cats compared with healthy cats (P = 0.02). Observed fecal scores were not significantly different between healthy and CKD cats.

CONCLUSIONS AND RELEVANCE

The observed BM frequency of cats with CKD was less than apparently healthy cats and represents a clinically important variation from normal.

Gastrointestinal symptom burden and dietary intake in patients with chronic kidney disease

BACKGROUND

Gastrointestinal (GI) symptoms can present a significant burden to patients with chronic kidney disease (CKD) but the reported prevalence is inconsistent.

OBJECTIVE

To examine the GI burden and dietary intake in patients with CKD with or without dialysis.

METHODS

This was a cross-sectional study of 216 adults, recruited from outpatient and dialysis clinics, with CKD stage 4 or 5 not receiving dialysis (CKD-ND), or receiving haemodialysis (HD) or peritoneal dialysis (PD). Three questionnaires were administered: the Bristol Stool Form Scale (BSFS); a modified Gastrointestinal Symptom Rating Scale and a short Food Frequency Questionnaire. Outcomes were stool frequency and consistency, GI symptoms and dietary intake.

RESULTS

Data were collected from 216 patients (mean age, 63 years [95% CI: 61, 65]; 63% males; CKD-ND: n = 134; HD: n = 67; PD: n = 15). Mean stool frequency for all groups was one bowel action per day (p = .45) and consistency was normal (BSFS type 4, p = .95). Overall GI symptom burden was low but several symptoms occurred at least "most of the time" including "tiredness/lethargy" (54% of participants), "reduced appetite" (29%), "early satiety" (25%) and "change in taste" (15%). Low intakes of fresh fruit, vegetables, whole-grains and legumes were found. No associations were observed between diet and GI symptoms.

CONCLUSION

The overall GI symptom burden was low, but >15% of participants reported several symptoms as occurring most to all of the time. Low intakes of fresh fruit, vegetables, whole-grains and legumes were observed in all CKD patients.

Chronic Kidney Disease, Gut Dysbiosis, and Constipation: A Burdensome Triplet

Gut dysbiosis has been implicated in the progression of chronic kidney disease (CKD). Alterations in the gut environment induced by uremic toxins, the dietary restriction of fiber-rich foods, and multiple drugs may be involved in CKD-related gut dysbiosis. CKD-related gut dysbiosis is considered to be characterized by the expansion of bacterial species producing precursors of harmful uremic toxins, such as indoxyl sulfate and p-cresyl sulfate, and the contraction of species generating beneficial short-chain fatty acids, such as butyrate. Gut-derived uremic toxins cause oxidative stress and pro-inflammatory responses, whereas butyrate exerts anti-inflammatory effects and contributes to gut epithelial integrity. Gut dysbiosis is associated with the disruption of the gut epithelial barrier, which leads to the translocation of endotoxins. Research on CKD-related gut dysbiosis has mainly focused on chronic inflammation and consequent cardiovascular and renal damage. The pathogenic relationship between CKD-related gut dysbiosis and constipation has not yet been investigated in detail. Constipation is highly prevalent in CKD and affects the quality of life of these patients. Under the pathophysiological state of gut dysbiosis, altered bacterial fermentation products may play a prominent role in intestinal dysmotility. In this review, we outline the factors contributing to constipation, such as the gut microbiota and bacterial fermentation; introduce recent findings on the pathogenic link between CKD-related gut dysbiosis and constipation; and discuss potential interventions. This pathogenic link needs to be elucidated in more detail and may contribute to the development of novel treatment options not only for constipation, but also cardiovascular disease in CKD.