April 2018: Abstract Roundup

CHRONIC KIDNEY DISEASE

Nondepressive Psychosocial Factors and Risk of CKD in Black Americans

Clinical Journal of the American Society of Nephrology. 2018;13(2):213-222

Researchers led by Joseph Lunyera, MD conducted a study to examine the association of nondepressive psychosocial factors with risk of chronic kidney disease (CKD) among black Americans. Data from the Jackson Heart Study were utilized for the current analysis.

The researchers identified underlying constructs from 12 psychosocial baseline variables: (1) perceived daily, lifetime, and burden of lifetime discrimination; stress; anger in; anger out; hostility; pessimism; John Henryism; spirituality; perceived social status; and social support. The association of those psychosocial variables with baseline CKD prevalence, estimated glomerular filtration rate (eGFR), and incident AKD was determined using multivariable models adjusted for demographics and comorbidity.

Of the participants in the Jackson Heart Study, 3390 (64%) had the required data; of those, 656 (19%) had prevalent CKD. Compared with participants with no CKD, those with CKD had lower perceived daily and lifetime discrimination, lower perceived stress, higher hostility, higher John Henryism, and higher pessimism. Three of the 12 psychosocial variables were identified using principal component analysis: factor 1, life stressors (perceived discrimination, stress); factor 2, moods (anger, hostility); and factor 3, coping strategies (John Henryism, spirituality, social status, social support).

At a median follow-up of 8 years, there was no significant association between identified psychosocial factors and eGFR decline or incident CKD.

“Greater life stressors were associated with lower prevalence of CKD at baseline in the Jackson Heart Study. However, psychosocial factors were not associated with risks of CKD over a median follow-up of 8 years,” the researchers concluded.

 

DIALYSIS

Vitamin D Status and Mortality Risk in Dialysis Patients

Nephrology Dialysis Transplantation. 2018:doi.org/10.1093/ndt/gfy016

It is common for patients on dialysis to experience vitamin D deficiency. The association between vitamin D deficiency and cardiovascular disease is well known; less certain is the relationship between serum 25-hydroxyvitamin D [25(OH)D] and all-cause and cardiovascular mortality in patients on dialysis. Yuhui Zhang, MD, and colleagues conducted a systematic review and meta-analysis to explore that relationship.

Searches on PubMed and Embase yielded 18 cohort studies representing 14,154 patients on dialysis. The studies were rated as moderate to high quality. The relative risk of all-cause mortality per 10 ng/mL increase in serum 25(OH)D level was 0.78 (95% confidence interval [CI}, 0.71-0.86). There was a marked heterogeneity partially explained by differences in prevalence of CKD, baseline parathyroid hormone levels, and dialysis duration in the studies.

The relative risk of cardiovascular risk per 10 ng/mL increase in serum 25(OH)D levels was 0.71 (95% CI, 0.63-0.79). The heterogeneity was explained by differences in study type and serum 25(OH)D measurement method.

In conclusion, the researchers said, “In the present study, increased serum 25(OH)D level was significantly associated with lower all-cause mortality and lower cardiovascular mortality in dialysis patients.”

 

Dialysis Initiation and Employment Status

Clinical Journal of the American Society of Nephrology. 2018;13(2):265-273

It can be challenging for patients with end-stage renal disease (ESRD) to remain employed following initiation of dialysis. There are few available data on when in the course of kidney disease most patients stop working. Kevin F. Erickson, MD, and colleagues recently conducted a study to examine employment trends over time among patients 18 to 54 years of age who initiated dialysis in the United States between 1996 and 2013. The researchers utilized data from a national ESRD registry.

The study compared unadjusted trends in employment at the start of dialysis and 6 months prior to ESRD. Following adjustment for patient characteristics and local unemployment rates in the general population, linear probability models were used to estimate changes in employment over time in ESRD patients. The researchers also examined employment among selected vulnerable patient populations as well as changes in employment in the 6 months prior to initiation of dialysis.

Throughout the study period, employment was low (23%-24%) among patients starting dialysis; 38% of patients who were employed 6 months before initiation of dialysis stopped working by the time of dialysis initiation. Following adjustment for observed characteristics, the probability of employment increased over time: patients who began dialysis between 2008 and 2013 had a 4.7% (95% confidence interval, 4.3%-5.1%) increase in the absolute probability of employment at dialysis start compared with patients who began dialysis between 1996 and 2001. Black and Hispanic patients were less likely to be employed at the start of dialysis compared with other patients; the gap narrowed during the study period.

In conclusion, the researchers said, “Although working-aged patients in the United States starting dialysis have experienced increases in the adjusted probability of employment over time, employment at the start of dialysis has remained low.”

 

PEDIATRIC NEPHROLOGY

Measuring Renal Volume in Pediatric Patients with ADPKD

Pediatric Nephrology. doi.org/10/1007/s00467-017-3862-6

In adults with autosomal dominant polycystic kidney disease (ADPKD), total kidney volume as measured by magnetic resonance imaging (MRI) is a validated marker of disease progression. However, MRI is burdensome in pediatric patients, creating a need for alternative measurement modalities.

In a recent study led by Luc Breysem, MD, kidney volume was measured in 30 pediatric patients with ADPKD using three-dimensional ultrasound (3DUS), applying the ellipsoid method (KV3DUS-ellipsoid) and manual contouring (KV3DUS-contour); manual contouring on MRI (KVMRI), and the ellipsoid method on two-dimensional ultrasound (2DUS, KV2DUS). Pearson’s r and Wilcoxon signed-rank tests were used to evaluate correlations and differences, and variability was evaluated using Bland-Altman plots.

All ultrasound volumetry methods showed significantly lower mean (±SD), compared with MRI-KV2DUS: 159 (±105); KV3DUS-contour: 185 (±110); KVMRI: 206 (±130) (all P<.001). All had a strong correlation with KVMRI. Prior to and following application of correction factor, Bland-Altman plots showed lower variability and absolute error for KV3DUS-contour versus KV2DUS and KV3DUS-ellipsoid.

“Compared with MRI, ultrasound volumetry was prone to underestimation. However, KV3DUS-contour represents a valuable alternative for MRI in early ADPKD. Although more time consuming, KV3DUS-contour is recommended over KV2DUS for estimation and follow-up in ADPKD children, given its smaller error.”

 

RENAL NUTRITION

Food Additives Contribute to Dietary Phosphorus and Potassium Loads

Journal of Renal Nutrition. 2018;28(2):83-90

To avoid hyperphosphatemia and hyperkalemia, both associated with increased risk of mortality, patients with chronic kidney disease (CKD) are advised to limit their dietary intake of phosphorus and potassium. The actual content of these minerals in the Canadian food supply is uncertain; both phosphorus and potassium are increasingly being used as food additives. A study conducted by Arti Sharma Parpia, RD, MSC, and colleagues was designed to examine the impact of food additives on the chemically analyzed content of phosphorus, potassium, sodium and protein in commonly consumed meat, poultry, and fish products (MPFs).

Results of a food frequency questionnaire in dialysis patients identified foods representing commonly consumed MPF; the foods were purchased from three major grocery store chains in Canada. Chemical analyses were conducted on foods with and without phosphorus and potassium additives listed on the ingredient list (n=76) and on foods that were additive free (reference MPFs; n=15).

Phosphorus, potassium, and sodium additives were listed on the ingredient list in 37%, 9%, and 72% of MPF, respectively. Among MPF categories that included a phosphorus additive, phosphorus content was significantly higher in MPF with phosphorus additives versus MPF without phosphorus additives and MPF reference foods (median: 270 vs 200 vs 210, respectively). Among categories containing a potassium additive, foods listing a potassium additive had significantly more potassium that foods that did not list potassium additives and reference foods (900 vs 325 vs 420, respectively).

In conclusion, the researchers said, “The use of additives in packaged MPF products as indicated by the ingredient list can significantly contribute to the dietary phosphorus and potassium loads in patients with CKD. Patients with CKD should be educated to avoid MPF foods listing phosphorus and/or potassium additives on the ingredients list, which may lead to improved dietary adherence.”

 

No Difference in Dietary Patterns in Patients with and without NODAT

Journal of Renal Nutrition. 2018;28(2):110-117

Analaura Contenaro, RD, and colleagues recently conducted a cross-sectional study designed to verify the association of dietary patterns and dietary components with new-onset diabetes mellitus after kidney transplantation (NODAT). The cohort included 116 adult kidney transplant recipients with no history of diabetes prior to transplantation; participants were followed up for a minimum of 1 year. The participants were recruited between January 2013 and August 2014.

A food frequency questionnaire was used to assess dietary intake, and cluster analysis was used to identify dietary patterns. Total energy, fiber, and cholesterol intake were calculated.

During the follow-up period, 28 patients developed NODAT. Compared with the non-NODAT group, those in the NODAT group had higher body mass index and body fat percentage, as well as higher levels of triglycerides and urinary protein/creatinine ratio.

Two dietary patterns (pattern I and pattern II) were identified: pattern II had higher intake of total, saturated, monounsaturated, and trans fats than pattern I. There was no association between the dietary patterns and NODAT, and there was no difference in the distribution of macronutrients, dietary fiber, and dietary cholesterol between the groups with and without NODAT.

“Posttransplant dietary patterns were not different between patients with and without NODAT. Further larger and prospective studies are needed to evaluate a possible relationship between dietary components and NODAT incidence in kidney transplant recipients,” the researchers concluded.

 

TRANSPLANTATION

Inflammation in Scarred Areas in Allografts Associated with T Cell-mediated Rejection

American Journal of Transplantation. 2018;18(2):377-390

There is an association between inflammation in fibrosis areas of kidney allografts (i-IF/TA) and allograft loss; however, the diagnostic significance of i-IF/TA is uncertain. Carmen Lefaucheur, MD, and colleagues recently conducted a prospective cohort study to examine the clinicohistologic phenotype and determinants of i-IF/Ta. The study included 1539 kidney transplant recipients who were undergoing evaluation of i-IF/TA and tubulitis in atrophic tubules (t-IF/TA) on protocol allograft biopsies at 1 year post transplantation.

Of the 1539 patients, 61.5% (n=946) presented interstitial fibrosis/tubular atrophy (IF/TA Banff grade >0) at 1 year posttransplant. Of those, 41.6% (n=394) showed i-IF/TA. There was a correlation between i-IF/TA and concurrent t-IF/TA (P<.001), interstitial inflammation (P<.001), tubulitis (P<.001), total inflammation (P<.001), peritubular capillaritis (P<.001), interstitial fibrosis (P<.001), and tubular atrophy (P=.02).

Previous T cell-mediated rejection (TCMR), BK virus nephropathy, steroid therapy, calcineurin inhibitor therapy, inosine-5’-monophosphate dehydrogenase inhibitor therapy, HLA-B mismatches, and HLA-DR mismatches were independent determinants of i-IF/TA (P<.001. P=.007, P=.039, P=.011, P=.011, P=.012, and P=.044, respectively). Over time, compared with those without posttreatment i-IF/TA, TCMR patients with i-IF/TA on posttreatment biopsy (n=83/136, 61.0%) exhibited accelerated progression of IF/TA (P=.01) as well as decreased 8-year allograft survival (70.8% vs 83.5%, P=.038).

The researchers concluded by saying, “Our results support that i-IF/TA may represent a manifestation of chronic active TCMR.”

 

Post-Transplant Changes in Frail Kidney Transplant Recipient HRQoL

Transplantation. 2018;102(2):291-299

Physical, mental, and kidney disease-specific scales are used to summarize health-related quality of life (HRQoL) among patients with end-stage renal disease. Components of HRQoL include disease burden, treatment effectiveness, and health status.

On average, HRQoL improves following kidney transplantation; however, the degree of change is dependent on the patient’s ability to withstand the stress of dialysis versus the ability to tolerate the intense physiologic changes associated with kidney transplantation. Either of those stressors may be more pronounced in frail kidney transplant recipients, affecting change in HRQoL after transplantation in that patient population.

Mara A. McAdams-DeMarco, MD, and colleagues conducted a study to quantify the short-term (3 months) rate of post-kidney transplant change in HRQoL by frailty status. Data on physical, mental, and kidney disease-specific HRQoL were gathered in a multicenter prospective cohort of 443 kidney transplant recipients (May 2014 to May 2017) using the Kidney Disease Quality of Life Instrument Short Form.

At the time of transplantation, mean HRQoL scores were 43.3 for physical, 52.8 for mental, and 72.6 for kidney disease-specific HRQoL. Scores for frail recipients were worse on the physical and kidney disease specific scales (P=.001 and P=.001, respectively); scores for frail recipients were similar on the mental health scale. Frail recipients experienced significantly greater rates of improvement in physical HRQoL compared with nonfrail recipients (1.35 points vs 0.34 points, respectively); frail recipients also experienced greater improvement in kidney disease-specific scores (3.75 points vs 2.41 points). There was no difference in improvement in mental HRQoL between frail and nonfrail recipients.

In conclusion, the researchers said, “Despite decreased physiologic reserve, frail recipients experience improvement in post-kidney transplantation physical and kidney disease-specific HRQoL better than nonfrail recipients.”