A prediction-based test for multiple endpoints

This article introduces a global hypothesis test intended for studies with multiple endpoints. Our test makes use of a priori predictions about the direction of the result of each endpoint and we weight these predictions using the sample correlation matrix. The global alternative hypothesis concerns a parameter, ϕ, defined as the researcher's ability to correctly predict the direction of each measure, essentially a binomial parameter. This allows for the test to include expected effects that are all positive, all negative or both while still using the cumulative information across those endpoints. A rejection of the null hypothesis (H0:ϕ≤ϕ0) provides evidence that the researcher's underlying theory about the natural process provides a better prediction of the observed results relative to the null hypothesized predictive ability, thus indicating the theory is worthy of further study. We compare our test to O'Brien's ordinary least squares (OLS) test and show that for small samples and situations where the effect is not in the same direction across all endpoints our approach has better power, while if the effect is equidirectional across all endpoints the OLS test can have greater power.

Randomized, Placebo-Controlled Trial of Rifaximin Therapy for Lowering Gut-Derived Cardiovascular Toxins and Inflammation in CKD

Background

Recent evidence suggests the systemic accumulation of by-products of gut microbes contributes to cardiovascular morbidity in patients with CKD. Limiting the generation of toxic bacterial by-products by manipulating the intestinal microbiota may be a novel strategy for reducing cardiovascular disease in CKD. Rifaximin is a minimally absorbed, oral antibiotic that targets intestinal pathogens and is commonly used as chronic therapy for the prevention of encephalopathy in patients with cirrhosis.

Methods

We conducted a randomized, double-blinded, placebo-controlled trial to determine the effect of a 10-day course of oral rifaximin 550 mg BID versus placebo on circulating concentrations of gut-derived cardiovascular toxins and proinflammatory cytokines in patients with stage 3-5 CKD (n=38). The primary clinical outcome was change in serum trimethylamine N-oxide (TMAO) concentrations from baseline to study end. Secondary outcomes included change in serum concentrations of p-cresol sulfate, indoxyl sulfate, kynurenic acid, deoxycholic acid, and inflammatory cytokines (C-reactive protein, IL-6, IL-1β), and change in composition and diversity of fecal microbiota.

Results

A total of 19 patients were randomized to each of the rifaximin and placebo arms, with n=17 and n=14 completing both study visits in these respective groups. We observed no difference in serum TMAO change (post-therapy minus baseline TMAO) between the rifaximin and placebo groups (mean TMAO change -3.9±15.4 for rifaximin versus 0.5±9.5 for placebo, P=0.49). Similarly, we found no significant change in serum concentrations for p-cresol sulfate, indoxyl sulfate, kynurenic acid, deoxycholic acid, and inflammatory cytokines. We did observe differences in colonic bacterial communities, with the rifaximin group exhibiting significant decreases in bacterial richness (Chao1, P=0.02) and diversity (Shannon H, P=0.05), along with altered abundance of several bacterial genera.

Conclusions

Short-term rifaximin treatment failed to reduce gut-derived cardiovascular toxins and inflammatory cytokines in patients with CKD.

Clinical Trial registry name and registration number

Rifaximin Therapy in Chronic Kidney Disease, NCT02342639.

Cognitive behavioral therapy for insomnia to enhance cognitive function and reduce the rate of Aβ deposition in older adults with symptoms of insomnia: A single-site randomized pilot clinical trial protocol

Lifestyle interventions to increase exercise and improve diet have been the focus of recent clinical trials to potentially prevent Alzheimer's disease (AD). However, despite the strong links between sleep disruptions, cognitive decline, and AD, sleep enhancement has yet to be targeted as a lifestyle intervention to prevent AD. A recent meta-analysis suggests that approximately 15% of AD may be prevented by an efficacious intervention aimed to reduce sleep disturbances and sleep disorders. Chronic insomnia is the most frequent sleep disorder occurring in at least 40% of older adults. Individuals with insomnia are more likely to be diagnosed with Alzheimer's Disease (AD) and demonstrate decline in cognitive function at long-term follow-up. AD is characterized by the accumulation of amyloid-β (Aβ) plaques and tau tangles in the brain, and growing evidence shows impaired sleep contributes to the accumulation of Aβ. An intervention aimed at improving insomnia may be a critical opportunity for primary prevention to slow cognitive decline and potentially delay the onset of AD. Cognitive behavioral therapy for insomnia (CBT-I) is an efficacious treatment for insomnia, but the use of CBT-I to improve cognitive function and potentially reduce the rate of Aβ accumulation has never been examined. Therefore, the objective of the proposed study is to examine the efficacy of CBT-I on improving cognitive function in older adults with symptoms of insomnia. An exploratory aim is to assess the effect of CBT-I on rate of Aβ accumulation.

Reliability of P3 Event-Related Potential During Working Memory Across the Spectrum of Cognitive Aging

Event-related potentials (ERPs) offer unparalleled temporal resolution in tracing distinct electrophysiological processes related to normal and pathological cognitive aging. The stability of ERPs in older individuals with a vast range of cognitive ability has not been established. In this test-retest reliability study, 39 older individuals (age 74.10 (5.4) years; 23 (59%) women; 15 non β-amyloid elevated, 16 β-amyloid elevated, 8 cognitively impaired) with scores on the Montreal Cognitive Assessment (MOCA) ranging between 3 and 30 completed a working memory (n-back) test with three levels of difficulty at baseline and 2-week follow-up. The main aim was to evaluate stability of the ERP on grand averaged task effects for both visits in the total sample (n = 39). Secondary aims were to evaluate the effect of age, group (non β-amyloid elevated; β-amyloid elevated, cognitively impaired), cognitive status (MOCA), and task difficulty on ERP reliability. P3 peak amplitude and latency were measured in predetermined channels. P3 peak amplitude at Fz, our main outcome variable, showed excellent reliability in 0-back (intraclass correlation coefficient (ICC), 95% confidence interval = 0.82 (0.67-0.90) and 1-back (ICC = 0.87 (0.76-0.93), however, only fair reliability in 2-back (ICC = 0.53 (0.09-0.75). Reliability of P3 peak latencies was substantially lower, with ICCs ranging between 0.17 for 2-back and 0.54 for 0-back. Generalized linear mixed models showed no confounding effect of age, group, or task difficulty on stability of P3 amplitude and latency of Fz. By contrast, MOCA scores tended to negatively correlate with P3 amplitude of Fz (p = 0.07). We conclude that P3 peak amplitude, and to lesser extent P3 peak latency, provide a stable measure of electrophysiological processes in older individuals.

Methods for training collaborative biostatisticians

The emphasis on team science in clinical and translational research increases the importance of collaborative biostatisticians (CBs) in healthcare. Adequate training and development of CBs ensure appropriate conduct of robust and meaningful research and, therefore, should be considered as a high-priority focus for biostatistics groups. Comprehensive training enhances clinical and translational research by facilitating more productive and efficient collaborations. While many graduate programs in Biostatistics and Epidemiology include training in research collaboration, it is often limited in scope and duration. Therefore, additional training is often required once a CB is hired into a full-time position. This article presents a comprehensive CB training strategy that can be adapted to any collaborative biostatistics group. This strategy follows a roadmap of the biostatistics collaboration process, which is also presented. A TIE approach (Teach the necessary skills, monitor the Implementation of these skills, and Evaluate the proficiency of these skills) was developed to support the adoption of key principles. The training strategy also incorporates a "train the trainer" approach to enable CBs who have successfully completed training to train new staff or faculty.

Exploratory analysis of mtDNA haplogroups in two Alzheimer's longitudinal cohorts

INTRODUCTION

Inherited mitochondrial DNA (mtDNA) variants may influence Alzheimer's disease (AD) risk.

METHODS

We sequenced mtDNA from 146 AD and 265 cognitively normal (CN) subjects from the University of Kansas AD Center (KUADC) and assigned haplogroups. We further considered 244 AD and 242 CN AD Neuroimaging Initiative (ADNI) subjects with equivalent data.

RESULTS

Without applying multiple comparisons corrections, KUADC haplogroup J AD and CN frequencies were 16.4% versus 7.6% (P = .007), and haplogroup K AD and CN frequencies were 4.8% versus 10.2% (P = .063). ADNI haplogroup J AD and CN frequencies were 10.7% versus 7.0% (P = .20), and haplogroup K frequencies were 4.9% versus 8.7% (P = .11). For the combined 390 AD and 507 CN cases haplogroup J frequencies were 12.8% versus 7.3% (P = .006), odds ratio (OR) = 1.87, and haplogroup K frequencies were 4.9% versus 9.5% (P = .010), OR = 0.49. Associations remained significant after adjusting for apolipoprotein E, age, and sex.

CONCLUSION

This exploratory analysis suggests inherited mtDNA variants influence AD risk.

Biological Efficacy and Safety of Niacinamide in Patients With ADPKD

INTRODUCTION

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive cyst enlargement, leading to kidney failure. Sirtuin-1 is upregulated in ADPKD and accelerates disease progression by deacetylating p53. Niacinamide is a dietary supplement that inhibits sirtuins at high doses.

METHODS

We conducted an open-label, single-arm intervention trial (study 1, N = 10), and a randomized, double blinded, placebo-controlled trial (study 2, N = 36) to assess the biological activity and safety of niacinamide. Patients with ADPKD were given 30 mg/kg oral niacinamide or placebo, for 12 months. The primary endpoint was the ratio of acetylated p53 to total p53 protein in peripheral blood mononuclear cells (PBMCs).

RESULTS

There was no sustained effect of niacinamide on acetylated/total p53 in either study and no difference between placebo and niacinamide arms. There was no difference in the change in height-adjusted total kidney volume over 12 months between niacinamide and placebo. Niacinamide was generally well tolerated. The most common adverse effects were nausea, diarrhea, gastroesophageal reflux, headache, and acneiform rash but there was no difference in their incidence between niacinamide and placebo.

CONCLUSIONS

In conclusion, niacinamide is safe and well-tolerated in patients with ADPKD. However, we were unable to detect a sustained inhibition of sirtuin activity over 12 months of treatment, and there was no signal to suggest a beneficial effect on any efficacy measure.

Safety and target engagement profile of two oxaloacetate doses in Alzheimer's patients

INTRODUCTION

Brain bioenergetics are defective in Alzheimer's disease (AD). Preclinical studies find oxaloacetate (OAA) enhances bioenergetics, but human safety and target engagement data are lacking.

METHODS

We orally administered 500 or 1000 mg OAA, twice daily for 1 month, to AD participants (n = 15 each group) and monitored safety and tolerability. To assess brain metabolism engagement, we performed fluorodeoxyglucose positron emission tomography (FDG PET) and magnetic resonance spectroscopy before and after the intervention. We also assessed pharmacokinetics and cognitive performance.

RESULTS

Both doses were safe and tolerated. Compared to the lower dose, the higher dose benefited FDG PET glucose uptake across multiple brain regions (P < .05), and the higher dose increased parietal and frontoparietal glutathione (P < .05). We did not demonstrate consistent blood level changes and cognitive scores did not improve.

CONCLUSIONS

1000 mg OAA, taken twice daily for 1 month, is safe in AD patients and engages brain energy metabolism.

Collective effects of age, sex, genotype, and cognitive status on fitness outcomes

INTRODUCTION

Individuals with Alzheimer's disease (AD) broadly exhibit lower cardiorespiratory fitness (CRF) compared to cognitively healthy older adults. Other factors, such as increasing age and female sex, are also known to track with lower CRF levels. However, it is unclear how these factors together with AD diagnosis and genetic risk (apolipoprotein e4 ; APOE4) collectively affect CRF.

METHODS

Our primary objective was to characterize the collective relationship of age, sex, APOE4 carrier status , and cognitive status (nondemented or AD) with two commonly reported CRF outcomes, VO2 max and oxygen uptake efficiency slope (OUES). To interrogate the unique and combined effect of age, sex, APOE4, and cognitive status on CRF, we pooled multiple datasets and tested several statistical models allowing all possible interactions.

RESULTS

AD diagnosis was consistently associated with lower maximal CRF, which declined with increasing age. APOE4 was also associated with lower maximal CRF (VO2max), but only in male subjects. Submaximal CRF (OUES) was lower in APOE4 carriers of both sexes, although this difference converged in male subjects with advancing age.

DISCUSSION

This multi-cohort analysis (n = 304) suggests that APOE4 carrier status and sex are important considerations for studies that evaluate maximal and submaximal CRF.

Rates of suicidal ideation among HIV-infected patients in care in the HIV Outpatient Study 2000-2017, USA

BACKGROUND

Suicidal ideation (SI) refers to an individual thinking about, considering or planning suicide. Identifying and characterizing persons with HIV (PWH) at greater risk for SI may lead to better suicide prevention strategies and quality of life improvement.

METHODS

Using clinical data gathered from medical chart abstraction for HIV Outpatient Study (HOPS) participants from 2000 to 2017, we assessed SI frequency among PWH in care and explored factors associated with the presence of SI diagnoses using linear mixed models analyses.

RESULTS

Among 6706 participants, 224 (3.3%) had a charted diagnosis of SI. Among those with SI, median age (interquartile range [IQR]) was 43.4 years [IQR: 38.7-50.3], median (IQR) CD4+ cell count was 439 cells/mm³ (IQR: 237-686), 71.4% were male, 54% were men who have sex with men (MSM), 25.4% heterosexual, and 13.4% persons who inject drugs. In multivariable analysis, persons at increased risk for SI were more likely to be: <50 years old (adjusted rate ratio [aRR] 1.86, 95% confidence interval [95%CI] 1.36-2.53), non-Hispanic/Latino black (aRR 1.75; 95%CI 1.29-2.38), have CD4+ cell count <350 cells/mm³ (aRR 1.32; 95%CI 1.05-1.65), have a viral load ≥50 copies/mL (aRR 1.49; 95%CI 1.12-1.98), have stopped antiretroviral therapy (aRR 1.46; 95%CI 1.10-1.95), have a history of: alcohol dependence (aRR 2.75; 95%CI 1.67-4.52), and drug overdose (aRR 4.09; 95%CI 2.16-7.71).

CONCLUSION

Routine mental health assessment and monitoring are needed in HIV clinical practice to better understand factors associated with SI and to inform the development of preventive interventions.

Trends for and Clinical Factors Associated with Choice of Oral P2Y12 Inhibitors for Patients on Chronic Dialysis

Background

Trends and clinical factors associated with prescribing choices for oral P2Y12 inhibitors (P2Y12-I) remain unknown for patients on chronic dialysis, i.e., with end-stage renal disease (ESRD).

Methods

From 2011–2014 U.S. Renal Data System registry, we identified 36,542 ESRD patients who received new prescriptions for P2Y12-I (median age 64.0 years and 54% males). Of the cohort, 93% were receiving hemodialysis and 7% on peritoneal dialysis. We analyzed trends and investigated clinical factors associated with specific P2Y12-I prescribed.

Results

Clopidogrel was prescribed for 95%, prasugrel for 3%, and ticagrelor for 2%. Clopidogrel was favored for those ≥75 years (18% of cohort). Compared to Caucasians, African Americans (36% of cohort) and Hispanics (19% of cohort) were less likely to receive prasugrel and ticagrelor (P<0.05). Patients receiving hemodialysis versus peritoneal dialysis were less likely to receive prasugrel over clopidogrel, adjusted odds ratio (aOR) 0.67 (0.55-0.82). Each additional year of dialysis decreased the odds of receiving prasugrel over clopidogrel, aOR 0.91 (0.85-0.98). History of atrial fibrillation reduced the odds of receiving ticagrelor or prasugrel over clopidogrel, aOR 0.69 (0.54-0.89) and 0.73 (0.60-0.89), respectively. Concomitant oral anticoagulant use was not associated with choice of P2Y12-I. Occurrence of non-ST segment elevation myocardial infarction or percutaneous coronary intervention within the 6-month period prior to the index date favored ticagrelor over prasugrel, aOR 1.31 (1.06-1.62) and 1.29 (1.01-1.66), respectively. However, prescribing trends favoring ticagrelor over prasugrel were not observed for deployment of drug-eluting, or multiple coronary stents.

Conclusion

Between 2011 and 2014, clopidogrel remained the most common P2Y12-I whereas ticagrelor and prasugrel remained underutilized in ESRD patients. Prescribing practices for these drugs were based upon clinically approved indication for their use in the general population as well as perceived complexity of an ESRD patient including demographics, dialysis-related factors and comorbidities. Comparative effectiveness studies involving ESRD patients are needed to prove that ticagrelor and prasugrel are just as safe and effective as clopidogrel before clinicians can make informed decisions for choice of P2Y12-I in this patient population.

Electronic supplementary material

The online version of this article (10.1007/s10557-019-06913-w) contains supplementary material, which is available to authorized users.

A semi-automated pipeline for fulfillment of resource requests from a longitudinal Alzheimer's disease registry

Objective

Managing registries with continual data collection poses challenges, such as following reproducible research protocols and guaranteeing data accessibility. The University of Kansas (KU) Alzheimer’s Disease Center (ADC) maintains one such registry: Curated Clinical Cohort Phenotypes and Observations (C3PO). We created an automated and reproducible process by which investigators have access to C3PO data.

Materials and Methods

Data was input into Research Electronic Data Capture. Monthly, data part of the Uniform Data Set (UDS), that is data also collected at other ADCs, was uploaded to the National Alzheimer’s Coordinating Center (NACC). Quarterly, NACC cleaned, curated, and returned the UDS to the KU Data Management and Statistics (DMS) Core, where it was stored in C3PO with other quarterly curated site-specific data. Investigators seeking to utilize C3PO submitted a research proposal and requested variables via the publicly accessible and searchable data dictionary. The DMS Core used this variable list and an automated SAS program to create a subset of C3PO.

Results

C3PO contained 1913 variables stored in 15 datasets. From 2017 to 2018, 38 data requests were completed for several KU departments and other research institutions. Completing data requests became more efficient; C3PO subsets were produced in under 10 seconds.

Discussion

The data management strategy outlined above facilitated reproducible research practices, which is fundamental to the future of research as it allows replication and verification to occur.

Conclusion

We created a transparent, automated, and efficient process of extracting subsets of data from a registry where data was changing daily.

The Impact of Creative Arts in Alzheimer's Disease and Dementia Public Health Education

Previous research involving dramatic performances about Alzheimer's disease and dementia perception have targeted health care workers or caretakers. We examined the influence of a theater performance on the emotional affect of a general audience to determine the utility of this type of theater in large-scale public health education efforts. Our study included 147 participants that attended a self-revelatory theater performance based on the social/relationship experiences of those with dementia and those who care for them. This type of theater engages the audience and actors in a dual transformative process, supporting the emotional growth of all involved. Participants completed pre- and post-performance questionnaires regarding their beliefs and feelings surrounding the topic of dementia and the importance of the Arts for educating on issues surrounding dementia care. We tested for change in emotional affect pre- and post-performance using sensitivity and center of gravity statistical analyses. We found a significant change in emotional affect from an initial strong negative affect to slightly more positive/relaxed view after viewing the performance. Findings support self-revelatory theater as a resource to destigmatize preconceived notions of dementia. Large-scale community health education efforts could benefit from using this style of theater to elicit a change in audience perception of disease realities.

Subclinical Cognitive Impairment and Listing for Kidney Transplantation

BACKGROUND AND OBJECTIVES

Cognitive impairment is common in patients with kidney disease and can affect physicians' perception and/or patients' ability to complete the pretransplant evaluation. We examined whether cognitive impairment influences the likelihood for transplant listing and whether patients with cognitive impairment take longer to be listed.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a single-center longitudinal cohort study. Patients presenting for their index kidney transplant evaluation were screened for cognitive impairment using the Montreal Cognitive Assessment. A score <26 indicated cognitive impairment. The transplant selection committee was blinded to the scores. Kaplan-Meier analysis assessed time to active listing by level of cognition. A Cox proportional hazards model that included age, sex, race/ethnicity, smoking, coronary artery disease, and diabetes was constructed to evaluate the association between Montreal Cognitive Assessment score and listing for transplant.

RESULTS

In total, 349 patients who underwent Montreal Cognitive Assessment testing at their initial visit were included in the analysis. Patients with cognitive impairment were more likely to be older, black, and smokers. The time to listing in patients with cognitive impairment was longer than the time to listing in those with no cognitive impairment (median time, 10.6 versus 6.3 months; log rank test P=0.01). Cognitive impairment was independently associated with a lower likelihood of being listed for transplant (hazard ratio, 0.93 per unit lower Montreal Cognitive Assessment score; 95% confidence interval, 0.88 to 0.99; P=0.02). A lower proportion of patients with cognitive impairment were listed compared with patients without cognitive impairment at 1 month (2% versus 11%), 6 months (17% versus 37%), and 1 year (23% versus 41%), (P<0.001 for all).

CONCLUSIONS

Cognitive impairment is associated with a lower likelihood of being listed for kidney transplant, and is associated with longer time to transplant listing.

Trimethylamine N-Oxide and Cardiovascular Outcomes in Patients with ESKD Receiving Maintenance Hemodialysis

BACKGROUND AND OBJECTIVES

Trimethylamine N-oxide (TMAO), a compound derived from byproducts of intestinal bacteria, has been shown to accelerate atherosclerosis in rodents. To date, there are conflicting data regarding the association of serum TMAO with cardiovascular outcomes in patients with ESKD, a population exhibiting both high serum TMAO and excessive atherosclerosis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We measured baseline serum TMAO concentrations in a subset of participants (n=1243) from the Evaluation of Cinacalcet Hydrochloride Therapy to Lower Cardiovascular Events (EVOLVE) trial and conducted post hoc analyses evaluating the association between baseline serum TMAO and cardiovascular outcomes.

RESULTS

We observed a wide distribution of serum TMAO in our cohort, with approximately 80% of participants exhibiting TMAO concentrations ≥56 µM and a maximum TMAO concentration of 1103.1 µM. We found no association between TMAO and our primary outcome, a composite of cardiovascular mortality, myocardial infarction, peripheral vascular event, stroke, and hospitalization for unstable angina. Moreover, in unadjusted and adjusted analyses, we observed no relation between TMAO and all-cause mortality, the independent components of our composite outcome, or the original EVOLVE primary outcome. Although we did observe higher TMAO concentrations in white participants, further subgroup analyses did not confirm the previously identified interaction between TMAO and race observed in a prior study in patients receiving dialysis.

CONCLUSIONS

We found no evidence linking TMAO to adverse clinical outcomes in patients receiving maintenance hemodialysis with moderate to severe secondary hyperparathyroidism.

Application of risk factors for venous thromboembolism in patients with multiple myeloma starting chemotherapy, a real-world evaluation

INTRODUCTION

Within the first year of diagnosis, up to 1 in 3 multiple myeloma (MM) patients will experience a venous thromboembolism (VTE). The International Myeloma Working Group (IMWG) has thromboprophylaxis guidelines that stratify patients into low or high risk for thrombosis and subsequently recommend thromboprophylaxis, but it is unknown if these recommendations are being followed or if they are effective. The purpose of this study was to assess efficacy of the IMWG guidelines and investigate other potential VTE risk factors.

METHODS

Study participants were treated at the University of Kansas Medical Center between 2007 and 2013, and charts were reviewed to extract data. Cases (MM and VTE) were matched to controls (MM and no VTE) at approximately 1:3 ratio based on gender, age (±5 years), and time of MM diagnosis (±5 years).

RESULTS

A total of 80 cases and 211 controls were matched. Most patients (82%) were considered high risk for experiencing a VTE at the time of their MM diagnosis and 18% were considered low risk. Neither risk category (P = 0.16) nor thromboprophylaxis at baseline (P = 0.37) predicted VTE, though cases were more likely than controls to have an increased risk of thrombosis at the time of clot compared to their baseline risk (P = 0.09).

CONCLUSION

Our results suggest that IMWG guidelines are not being consistently followed and therefore could not be validated. Additional risk factors were not identified, but risk for VTE may change over time suggesting patients may require ongoing assessment of VTE risk and thromboprophylaxis throughout the disease course.

Relationship between caffeine intake and autosomal dominant polycystic kidney disease progression: a retrospective analysis using the CRISP cohort

Background

Caffeine has been proposed, based on in vitro cultured cell studies, to accelerate progression of autosomal dominant polycystic kidney disease (ADPKD) by increasing kidney size. Since ADPKD patients are advised to minimize caffeine intake, we investigated the effect of caffeine on disease progression in the Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease (CRISP), a prospective, observational cohort study.

Methods

Our study included 239 patients (mean age = 32.3 ± 8.9 ys; 188 caffeine consumers) with a median follow-up time of 12.5 years. Caffeine intake reported at baseline was dichotomized (any vs. none). Linear mixed models, unadjusted and adjusted for age, race, sex, BMI, smoking, hypertension, genetics and time, were used to model height-adjusted total kidney volume (htTKV) and iothalamate clearance (mGFR). Cox proportional hazards models and Kaplan-Meier plots examined the effect of caffeine on time to ESRD or death.

Results

Caffeine-by-time was statistically significant when modeling ln(htTKV) in unadjusted and adjusted models (p <  0.01) indicating that caffeine consumers had slightly faster kidney growth (by 0.6% per year), but htTKV remained smaller from baseline throughout the study. Caffeine consumption was not associated with a difference in mGFR, or in the time to ESRD or death (p > 0.05). Moreover the results were similar when outcomes were modeled as a function of caffeine dose.

Conclusion

We conclude that caffeine does not have a significant detrimental effect on disease progression in ADPKD.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1182-0) contains supplementary material, which is available to authorized users.

A Mitochondrial Biomarker-Based Study of S-Equol in Alzheimer's Disease Subjects: Results of a Single-Arm, Pilot Trial

Reductions in bioenergetic fluxes, mitochondrial enzyme activities, and mitochondrial number are observed in Alzheimer's disease (AD). Preclinical work indicates estrogen pathway signaling by either estrogen or selective β estrogen receptor (ERβ) agonists benefits these parameters. To assess whether an ERβ agonist could improve mitochondrial function in actual AD subjects, we administered S-equol (10 mg twice daily) to 15 women with AD and determined the platelet mitochondria cytochrome oxidase (COX) activity before initiating S-equol (lead-in), after two weeks of S-equol (active treatment), and two weeks after stopping S-equol (wash-out). Because the intra-individual variation of this enzyme across samples taken at different times was unknown we used a nonparametric, single-arm, dichotomous endpoint that classified subjects whose active treatment COX activity exceeded the average of their lead-in and wash-out measures as positive responders. Eleven positive responses were observed (p < 0.06). The implications of this finding on our null hypothesis (that S-equol does not influence platelet mitochondria COX activity) are discussed. To our knowledge, this is the first time a direct mitochondrial target engagement biomarker has been utilized in an AD clinical study.

Association of Slow Graft Function with Long-Term Outcomes in Kidney Transplant Recipients

Background

Whether slow graft function (SGF) represents an intermediate phenotype between immediate graft function (IGF) and delayed graft function (DGF) in kidney transplant recipients is unknown.

Material/Methods

In a retrospective cohort analysis of 1,222 kidney transplant recipients, we classified patients as having IGF, SGF, and DGF using two different schemas. SGF was defined as serum creatinine (Cr) ≥3.0 mg/dL by postoperative day 5 in Schema 1, and in Schema 2, SGF was defined as Cr >1.5 mg/dL plus a creatinine reduction ratio <20% between postoperative days 1 and 3. A complementary log-log model was used to examine the association of graft function with graft survival and patient survival.

Results

Mean age of study patients was 51.5±13.3 years, 59.9% were male, and 66.7% were white. In Schema 1, SGF and DGF were associated with comparable increases in risk of graft failure compared to IGF (hazard ratio (HR) 1.46, 95% confidence intervals (CI) 1.02–2.10 for SGF and HR 1.56, CI 1.11–2.22 for IGF); estimates were similar for Schema 2 (HR 1.52, CI 1.05–2.20 for SGF and HR 1.54, CI 1.10–2.17 for IGF). However, for mortality, outcomes for SGF were similarly to IGF, both SGF and IGF were associated with lower risk relative to DGF (HR 0.54, CI 0.36–0.80 for SGF in Schema 1; HR 0.58, CI 0.39–0.85 for SGF in Schema 2).

Conclusions

These findings suggest that SGF may be a marker for graft failure but not for mortality, and SGF may therefore represent a phenotype separate from IGF and DGF.

Feasibility and efficacy data from a ketogenic diet intervention in Alzheimer's disease

Introduction

We assessed the feasibility and cognitive effects of a ketogenic diet (KD) in participants with Alzheimer's disease.

Methods

The Ketogenic Diet Retention and Feasibility Trial featured a 3-month, medium-chain triglyceride-supplemented KD followed by a 1-month washout in clinical dementia rating (CDR) 0.5, 1, and 2 participants. We obtained urine acetoacetate, serum β-hydroxybutyrate, food record, and safety data. We administered the Alzheimer's Disease Assessment Scale-cognitive subscale and Mini-Mental State Examination before the KD, and following the intervention and washout.

Results

We enrolled seven CDR 0.5, four CDR 1, and four CDR 2 participants. One CDR 0.5 and all CDR 2 participants withdrew citing caregiver burden. The 10 completers achieved ketosis. Most adverse events were medium-chain triglyceride-related. Among the completers, the mean of the Alzheimer's Disease Assessment Scale-cognitive subscale score improved by 4.1 points during the diet (P = .02) and reverted to baseline after the washout.

Discussion

This pilot trial justifies KD studies in mild Alzheimer's disease.