Tissue sodium stores in peritoneal dialysis and hemodialysis patients determined by 23-sodium magnetic resonance imaging

BACKGROUND

Tissue sodium content in patients on maintenance hemodialysis (MHD) and peritoneal dialysis (PD) were previously explored using 23Sodium magnetic resonance imaging (23NaMRI). Larger studies would provide a better understanding of sodium stores in patients on dialysis as well as the factors influencing this sodium accumulation.

METHODS

In this cross-sectional study, we quantified the calf muscle and skin sodium content in 162 subjects (10 PD, 33 MHD patients, and 119 controls) using 23NaMRI. Plasma levels of interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) were measured to assess systemic inflammation. Sixty-four subjects had repeat 23NaMRI scans that were analyzed to assess the repeatability of the 23NaMRI measurements.

RESULTS

Patients on MHD and PD exhibited significantly higher muscle and skin sodium accumulation compared to controls. African American patients on dialysis exhibited greater muscle and skin sodium content compared to non-African Americans. Multivariable analysis showed that older age was associated with both higher muscle and skin sodium. Male sex was also associated with increased skin sodium deposition. Greater ultrafiltration was associated with lower skin sodium in patients on PD (Spearman's rho=-0.68, P = 0.035). Higher plasma IL-6 and hsCRP levels correlated with increased muscle and skin sodium content in the overall study population. Patients with higher baseline tissue sodium content exhibited greater variability in tissue sodium stores on repeat measurements.

CONCLUSIONS

Our findings highlight greater muscle and skin sodium content in dialysis patients compared to controls without kidney disease. Tissue sodium deposition and systemic inflammation seen in dialysis patients might influence one another bidirectionally.

Effects of long-term intradialytic oral nutrition and exercise on muscle protein homeostasis and markers of mitochondrial content in patients on hemodialysis

Patients with end-stage kidney disease on maintenance hemodialysis commonly develop protein-energy wasting, a syndrome characterized by nutritional and metabolic abnormalities. Nutritional supplementation and exercise are recommended to prevent protein-energy wasting. In a 6-mo prospective randomized, open-label, clinical trial, we reported that the combination of resistance exercise and nutritional supplementation does not have an additive effect on lean body mass measured by dual-energy X-ray absorptiometry. To provide more mechanistic data, we performed a secondary analysis where we hypothesized that the combination of nutritional supplementation and resistance exercise would have additive effects on muscle protein accretion by stable isotope protein kinetic experiments, muscle mass by MRI, and mitochondrial content markers in muscle. We found that 6 mo of nutritional supplementation during hemodialysis increased muscle protein net balance [baseline: 2.5 (-17.8, 13.0) µg·100 mL-1·min-1 vs. 6 mo: 43.7 (13.0, 98.5) µg·100 mL-1·min-1, median (interquartile range), P = 0.04] and mid-thigh fat area [baseline: 162.3 (104.7, 226.6) cm2 vs. 6 mo: 181.9 (126.3, 279.2) cm2, median (interquartile range), P = 0.04]. Three months of nutritional supplementation also increased markers of mitochondrial content in muscle. Although the study is underpowered to detected differences, the combination of nutritional supplementation and exercise failed to show further benefit in protein accretion or muscle cross-sectional area. We conclude that long-term nutritional supplementation increases the skeletal muscle anabolic effect, the fat cross-sectional area of the thigh, and markers of mitochondrial content in skeletal muscle.

Serious Illness Treatment Preferences for Older Adults with Advanced CKD

BACKGROUND

Patient-centered care for older adults with CKD requires communication about patient's values, goals of care, and treatment preferences. Eliciting this information requires tools that patients understand and that enable effective communication about their care preferences.

METHODS

Nephrology clinic patients age ≥60 years with stage 4 or 5 nondialysis-dependent CKD selected one of four responses to the question, "If you had a serious illness, what would be important to you?" Condensed versions of the options were, "Live as long as possible;" "Try treatments, but do not suffer;" "Focus on comfort;" or "Unsure." Patients also completed a validated health outcome prioritization tool and an instrument determining the acceptability of end-of-life scenarios. Patient responses to the three tools were compared.

RESULTS

Of the 382 participants, 35% (n=134) selected "Try treatments, but do not suffer;" 33% (n=126) chose "Focus on comfort;" 20% (n=75) opted for "Live as long as possible;" and 12% (n=47) selected "Unsure." Answers were associated with patients' first health outcome priority and acceptability of end-of-life scenarios. One third of patients with a preference to "Focus on comfort" reported that a life on dialysis would not be worth living compared with 5% of those who chose "Live as long as possible" (P<0.001). About 90% of patients agreed to share their preferences with their providers.

CONCLUSIONS

Older adults with advanced CKD have diverse treatment preferences and want to share them. A single treatment preference question correlated well with longer, validated health preference tools and may provide a point of entry for discussions about patient's treatment goals.

The measurement invariance of schizotypy in Europe

The short version of the Oxford-Liverpool Inventory of Feelings and Experiences (sO-LIFE) is a widely used measure assessing schizotypy. There is limited information, however, on how sO-LIFE scores compare across different countries. The main goal of the present study is to test the measurement invariance of the sO-LIFE scores in a large sample of non-clinical adolescents and young adults from four European countries (UK, Switzerland, Italy, and Spain). The scores were obtained from validated versions of the sO-LIFE in their respective languages. The sample comprised 4190 participants (M=20.87 years; SD=3.71 years). The study of the internal structure, using confirmatory factor analysis, revealed that both three (i.e., positive schizotypy, cognitive disorganisation, and introvertive anhedonia) and four-factor (i.e., positive schizotypy, cognitive disorganisation, introvertive anhedonia, and impulsive nonconformity) models fitted the data moderately well. Multi-group confirmatory factor analysis showed that the three-factor model had partial strong measurement invariance across countries. Eight items were non-invariant across samples. Significant statistical differences in the mean scores of the s-OLIFE were found by country. Reliability scores, estimated with Ordinal alpha ranged from 0.75 to 0.87. Using the Item Response Theory framework, the sO-LIFE provides more accuracy information at the medium and high end of the latent trait. The current results show further evidence in support of the psychometric proprieties of the sO-LIFE, provide new information about the cross-cultural equivalence of schizotypy and support the use of this measure to screen for psychotic-like features and liability to psychosis in general population samples from different European countries.

Ethnicity, violent offending, and vulnerability to schizophrenia: a pilot study

Previous research has highlighted increased risk for schizophrenia in Afro-Caribbeans as well as over-representation in the prison population. This small-scale study examined the relationship between criminality, ethnicity, and psychosis-proneness in a male prison sample. Twenty British Caucasian and 20 Afro-Caribbean prisoners were divided into equal sub-groups of violent and non-violent offenders. Participants completed measures of schizotypy, delusional ideation, and hostility. Afro-Caribbean offenders scored more highly on negative schizotypy and delusional ideation than their Caucasian counterparts. Violent offenders scored more highly on the positive symptoms of schizotypy than non-violent prisoners. Both ethnicity and violent offending may be relevant factors when considering vulnerability to psychosis in the offending population.