Lower creatinine as a marker of malnutrition and lower muscle mass in hemodialysis patients

Genetic analysis of elevated levels of creatinine and cystatin C biomarkers reveals novel genetic loci associated with kidney function

The rising prevalence of chronic kidney disease (CKD), affecting an estimated 37 million adults in the United States, presents a significant global health challenge. CKD is typically assessed using estimated Glomerular Filtration Rate (eGFR), which incorporates serum levels of biomarkers such as creatinine and cystatin C. However, these biomarkers do not directly measure kidney function; their elevation in CKD results from diminished glomerular filtration. Genome-wide association studies (GWAS) based on eGFR formulas using creatinine (eGFRcre) or cystatin C (eGFRcys) have identified distinct non-overlapping loci, raising questions about whether these loci govern kidney function or biomarker metabolism. In this study, we show that GWAS on creatinine and cystatin C levels in healthy individuals reveal both nonoverlapping genetic loci impacting their metabolism as well as overlapping genetic loci associated with kidney function; whereas GWAS on elevated levels of these biomarkers uncover novel loci primarily associated with kidney function in CKD patients.

Lower prognostic nutritional index is associated with a greater decline in long-term kidney function in general population

BACKGROUND

The prognostic nutritional index (PNI) is an integrated index of serum albumin and peripheral lymphocyte count, where low values may reflect poor nutritional status or inflammation. The long-term effect of PNI on renal function is not well known in the general population. Therefore, we investigated whether the PNI is related to renal function changes in the general population.

METHODS

Data from participants who underwent a health check-up between 2002 and 2018 were retrospectively examined. PNI was computed by 10×serum albumin (g/dL) + 0.005×total lymphocyte count (per mm3). The primary exposure was PNI, divided into quintiles. The primary outcome was a 25% decline in eGFR from baseline over a 5-year follow-up period.

RESULTS

This study included 15,437 participants (mean [standard deviation, SD] age, 43.7 [7.9] years; 46% male). The median (interquartile ranges) 5-year change of eGFR was - 5.2 (- 18.8, - 3.3) mL/min/1.73m2. A total of 2,272 participants (14.7%) experienced a 25% decline in eGFR at 5 years. Compared to the highest PNI group, lower PNI groups were at greater risk for a 25% decline in eGFR; odds ratios and 95% confidence intervals were 1.42 (1.20, 1.68), 1.23 (1.04, 1.45), 1.21 (1.03, 1.43), and 1.19 (1.01, 1.40) for the first to fourth quintiles of PNI, respectively. In linear regression analyses, lower PNI groups also showed a larger decline in eGFR over 5 years compared to the highest PNI group.

CONCLUSIONS

Lower PNI was associated with a larger decline in renal function in the general population.

Malnutrition, protein energy wasting and sarcopenia in patients attending a haemodialysis centre in sub-Saharan Africa

BACKGROUND

Haemodialysis (HD) patients are reported to be at greater risk of malnourishment, and at risk of increased morbidity and mortality. However, most studies report from economically advanced countries. We therefore assessed the nutritional status and diet among HD patients attending a public university hospital in a sub-Saharan African country.

SUBJECTS

We performed nutritional assessments in HD patients attending the largest dialysis centre, in the country, collecting demographic and clinical data, dietary intake, along with anthropometric and bioimpedance body composition measurements in May 2022. Malnutrition was classified according to subjective global assessment score (SGA). Additional assessments of protein energy wasting (PEW), clinical frailty, and sarcopenia were made.

RESULTS

All 97 HD patients were recruited, mean age 44.7 ± 12.2 years, with 55 (56.7%) males. Malnutrition was present in 43.8%, PEW 20.6%, frailty 17.6% and sarcopenia 4.1%. On multivariable logistic regression higher serum albumin (adjusted odds ratio (AOR) 0.89, 95% confidence intervals (CI) 0.85-0.95, p < 0.001), creatinine (AOR 0.99, 95%CI 0.98-0.99, p < 0.001), greater mid upper arm circumference (AOR 0.89, 95%CI 0.83-0.95, p = 0.001), body cell mass (BCM) (AOR 0.79, 95%CI 0.67-0.95, p = 0.013) and employment (AOR 0.45, 95%CI 0.23-0.87, p = 0.017), were are all protective against malnourishment. Almost 75% had reduced dietary protein intake.

CONCLUSIONS

Despite a younger, less co-morbid patient population, malnutrition is common in this resource poor setting. The staple diet is based on maize, a low protein foodstuff. Employment improved finances and potentially allows better nutrition. Further studies are required to determine whether additional dietary protein can reduce the prevalence of malnutrition in this population.

Low serum creatinine to cystatin C ratio is independently associated with sarcopenia and high carotid plaque score in patients with type 2 diabetes

BACKGROUND AND AIMS

Low serum creatinine (Cr) to cystatin C (cysC) ratio has been suggested to be associated with low muscle mass and strength and poor prognosis in various chronic disease. We investigated the associations of CCR with sarcopenia and carotid plaque score (PS) in patients with type 2 diabetes mellitus.

METHODS AND RESULTS

A total of 1577 patients with type 2 diabetes were enrolled. High PS was defined as PS ≥ 3. Sarcopenia was assessed by the measurement of appendicular skeletal muscle mass (ASM) and grip strength (GS). Compared to the highest CCR group, the lowest tertile group was older; had higher C-reactive protein levels, CIMT, and PS, but lower cysC-based estimated glomerular filtration rate (cysC-eGFR), ASM/BMI, and GS. Positive correlations between CCR and ASM/BMI (r = 0.239 in men and 0.303 in women, p < 0.001) and GS (r = 0.282 in men and 0.270 in women, p < 0.001) were observed in both genders. Odds ratios and 95% confidence intervals for high PS after adjusting for age and sex were 1.22 (0.92-1.61, p = 0.18) in the middle and 1.74 (1.31-2.30, p < 0.001) in the lowest tertiles, respectively, with those of the lowest tertile remaining significant after further adjusting for multiple confounders.

CONCLUSIONS

Low CCR was independently associated with sarcopenia and high PS in patients with type 2 diabetes mellitus, especially after adjusting for ASM/BMI and GS.

Outcomes Among Patients Hospitalized With COVID-19 and Acute Kidney Injury

RATIONALE & OBJECTIVE

Outcomes of patients hospitalized with coronavirus disease 2019 (COVID-19) and acute kidney injury (AKI) are not well understood. The goal of this study was to investigate the survival and kidney outcomes of these patients.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Patients (aged≥18 years) hospitalized with COVID-19 at 13 hospitals in metropolitan New York between March 1, 2020, and April 27, 2020, followed up until hospital discharge.

EXPOSURE

AKI.

OUTCOMES

Primary outcome: in-hospital death.

SECONDARY OUTCOMES

requiring dialysis at discharge, recovery of kidney function.

ANALYTICAL APPROACH

Univariable and multivariable time-to-event analysis and logistic regression.

RESULTS

Among 9,657 patients admitted with COVID-19, the AKI incidence rate was 38.4/1,000 patient-days. Incidence rates of in-hospital death among patients without AKI, with AKI not requiring dialysis (AKI stages 1-3), and with AKI receiving dialysis (AKI 3D) were 10.8, 31.1, and 37.5/1,000 patient-days, respectively. Taking those without AKI as the reference group, we observed greater risks for in-hospital death for patients with AKI 1-3 and AKI 3D (HRs of 5.6 [95% CI, 5.0-6.3] and 11.3 [95% CI, 9.6-13.1], respectively). After adjusting for demographics, comorbid conditions, and illness severity, the risk for death remained higher among those with AKI 1-3 (adjusted HR, 3.4 [95% CI, 3.0-3.9]) and AKI 3D (adjusted HR, 6.4 [95% CI, 5.5-7.6]) compared with those without AKI. Among patients with AKI 1-3 who survived, 74.1% achieved kidney recovery by the time of discharge. Among those with AKI 3D who survived, 30.6% remained on dialysis at discharge, and prehospitalization chronic kidney disease was the only independent risk factor associated with needing dialysis at discharge (adjusted OR, 9.3 [95% CI, 2.3-37.8]).

LIMITATIONS

Observational retrospective study, limited to the NY metropolitan area during the peak of the COVID-19 pandemic.

CONCLUSIONS

AKI in hospitalized patients with COVID-19 was associated with significant risk for death.

Sensitivity of ventrolateral posterior thalamic nucleus to back pain in alcoholism and CD4 nadir in HIV

Volumes of thalamic nuclei are differentially affected by disease-related processes including alcoholism and human immunodeficiency virus (HIV) infection. This MRI study included 41 individuals diagnosed with alcohol use disorders (AUD, 12 women), 17 individuals infected with HIV (eight women), and 49 healthy controls (24 women) aged 39 to 75 years. A specialized, high-resolution acquisition protocol enabled parcellation of five thalamic nuclei: anterior [anterior ventral (AV)], posterior [pulvinar (Pul)], medial [mediodorsal (MD)], and ventral [including ventral lateral posterior (VLp) and ventral posterior lateral (VPl)]. An omnibus mixed-model approach solving for volume considered the "fixed effects" of nuclei, diagnosis, and their interaction while covarying for hemisphere, sex, age, and supratentorial volume (svol). The volume by diagnosis interaction term was significant; the effects of hemisphere and sex were negligible. Follow-up mixed-model tests thus evaluated the combined (left + right) volume of each nucleus separately for effects of diagnosis while controlling for age and svol. Only the VLp showed diagnoses effects and was smaller in the AUD (p = .04) and HIV (p = .0003) groups relative to the control group. In the AUD group, chronic back pain (p = .008) and impaired deep tendon ankle reflex (p = .0005) were associated with smaller VLp volume. In the HIV group, lower CD4 nadir (p = .008) was associated with smaller VLp volume. These results suggest that the VLp is differentially sensitive to disease processes associated with AUD and HIV.