Guofen Yan

Serum β-2 Microglobulin Levels Predict Mortality in Dialysis Patients: Results of the HEMO Study

In the randomized Hemodialysis (HEMO) Study, chronic high-flux dialysis, as defined by higher beta-2 microglobulin (beta(2)M) clearance, compared with low-flux dialysis did not significantly alter all-cause mortality in the entire cohort but was associated with lower mortality in long-term dialysis patients. This analysis examined the determinants of serum beta(2)M levels and the associations of serum beta(2)M levels or dialyzer beta(2)M clearance with mortality. In a multivariable regression model that examined 1704 patients, baseline residual kidney urea clearance and dialyzer beta(2)M clearance were strong predictors of predialysis serum beta(2)M levels at 1 mo of follow-up, with regression coefficients of -7.21 (+/-0.69 SE) mg/L per ml/min per 35 L urea volume (P < 0.0001) and -1.94 (+/-0.30) mg/L per ml/min (P < 0.0001),respectively. In addition, black race and baseline years on dialysis correlated positively whereas age, diabetes, serum albumin, and body mass index correlated negatively with serum beta(2)M levels (P < 0.05). In time-dependent Cox regression models, mean cumulative predialysis serum beta(2)M levels but not dialyzer beta(2)M clearance were associated with all-cause mortality (relative risk = 1.11 per 10-mg/L increase in beta(2)M level; 95% confidence interval 1.05 to 1.19; P = 0.001), after adjustment for residual kidney urea clearance and number of prestudy years on dialysis. This association is supportive of the potential value of beta(2)M as a marker to guide chronic hemodialysis therapy.

Risk Factors for Hypertension in Chronic Hemodialysis Patients: Baseline Data from the HEMO Study

A cross-sectional analysis was performed to determine risk factors associated with hypertension in 1,238 chronic hemodialysis patients upon enrollment into the HEMO Study. The mean pre- and post-dialysis systolic blood pressure were 152.4 ± 25.0 (mean ± SD) and 137.8 ± 24.6 mm Hg, respectively. The mean pre- and post-dialysis diastolic blood pressures were 82.1 ± 14.8 and 74.7 ± 13.8 mm Hg, respectively. Less than 30% of the study cohort had blood pressures that were normotensive by JNC VI guidelines. Risk factors associated with higher pre- and post-dialysis systolic blood pressures included the presence of diabetes mellitus, older age, increased number of prescribed antihypertensive medications, lower hematrocrit, and absence of arrhythmias. Variables associated with higher pre- and post-dialysis diastolic blood pressures included younger age, increased number of prescribed anti-hypertensive medications and absence of arrhythmias. There was also a nonlinear relationship between blood pressure and prescribed total ultrafiltration volume. A total ultrafiltration volume of >2.5 kg was associated with an elevation in pre-dialysis systolic and diastolic blood pressures. A total ultrafiltration volume of ≤2.5 kg was associated with an elevation in post-dialysis systolic and diastolic blood pressures. These data on ultrafiltration volume suggest that higher pre-dialysis blood pressures may be associated with excessive interdialytic weight gains due to patient noncompliance with fluid restriction and that higher post-dialysis blood pressures may be associated with a prescribed dry weight that is higher than the patient’s true dry weight. Better management of these parameters may improve the prevalence and severity of hypertension in this population.

Association of acidosis and nutritional parameters in hemodialysis patients

There is extensive literature supporting an important role for acidosis in inducing net protein breakdown, both in experimental animals and humans. However, the clinical importance of the moderate intermittent metabolic acidosis frequently observed in hemodialysis patients has not been determined. We performed a cross-sectional analysis of the baseline laboratory data in the first 1,000 patients recruited to the Hemodialysis Study, looking for correlations between predialysis serum total carbon dioxide levels and parameters related to dietary intake and nutritional status. We found the mean predialysis serum total carbon dioxide level was moderately low (21.6 +/- 3.4 mmol/L; mean +/- SD) despite the use of bicarbonate dialysate and an average single-pool Kt/V of 1.54. Predialysis serum total carbon dioxide level correlated negatively with normalized protein catabolic rate (P < 0.001), suggesting patients with lower serum total carbon dioxide levels have a greater protein intake. The degree of acidosis observed in our patients does not seem to have a deleterious effect on the nutritional status of these patients because correlation of serum total carbon dioxide level with nutritional parameters, such as serum creatinine and serum albumin levels, was either negative or not statistically significant. Further investigation of the effect of modifying serum bicarbonate concentration on nutritional markers is needed to test these hypotheses.

Seasonal Variations in Clinical and Laboratory Variables among Chronic Hemodialysis Patients

Seasonal variations in BP among chronic hemodialysis patients have been reported. It was hypothesized that other characteristics of these patients might also vary with the seasons. Twenty-one clinical and laboratory variables were examined for seasonal variations among 1445 patients enrolled in the Hemodialysis Study, sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases. Mixed-effects models were applied to longitudinal changes (up to 45 mo) for individual patients for 19 of the 21 variables, which were measured at least twice each year, to determine the seasonal component of each variable. Seasonal variations in the other two variables, i.e., protein and energy intakes determined from annual dietary records, were assessed in cross-sectional comparisons of intakes of patients entering the study at different time points. Thirteen of the 21 variables examined demonstrated statistically significant (P < 0.01) seasonal components in their longitudinal variations. Predialysis blood urea nitrogen concentrations peaked in March, which coincided approximately with the peak protein catabolic rates, as well as protein and energy intakes (determined by dietary recall). Predialysis systolic and diastolic BP values were highest in winter and lowest in summer, corroborating previous reports. In addition, the lower predialysis BP values in summer were associated with higher outdoor temperatures and less interdialytic fluid gain. The mean predialysis hematocrit values were highest in July, which could not be attributed solely to the estimated changes in plasma volume. Seasonal variations in clinical and laboratory variables occur commonly among chronic hemodialysis patients. The reasons for most of these variations are not apparent and require further investigation. Nonetheless, failure to consider these variations might lead to biases in the interpretation of clinical studies. In addition, awareness of these variations might facilitate the interpretation of laboratory results and the clinical treatment of these patients.

Culturally Tailored Intervention for Rural African Americans With Type 2 Diabetes

Purpose The purpose of this pilot study was to evaluate a culturally tailored intervention for rural African Americans. Social Cognitive Theory provided the framework for the study. Methods Twenty-two participants were recruited and randomly assigned to either Group or Individual diabetes self-management (DSME). Group DSME included story-telling, hands-on activities, and problem-solving exercises. Individual DSME sessions focused on goal-setting and problem-solving strategies. Sessions were offered in an accessible community center over a 10-week period. Results Outcomes included glycosylated hemoglobin (A1C), self-care actions, self-efficacy level, goal attainment, and satisfaction with DSME. Participants in both Group and Individual DSME improved slightly over the 3-month period in self-care activities, A1C level, and goal attainment. Although differences were not statistically significant, trends indicate improved scores on dietary actions, foot care, goal attainment, and empowerment for those experiencing Group DSME. Conclusions The culturally tailored approach was well received by all participants. Improvements among those receiving Individual DSME may indicate that brief sessions using a culturally tailored approach could enhance self-care and glycemic control. Additional testing among more participants over a longer time period is recommended.

Association between Serum β2-Microglobulin Level and Infectious Mortality in Hemodialysis Patients

BACKGROUND AND OBJECTIVES Secondary analysis of the Hemodialysis Study showed that serum beta(2)-microglobulin levels predicted all-cause mortality and that high-flux dialysis was associated with decreased cardiac deaths in hemodialysis patients. This study examined the association of serum beta(2)-microglobulin levels and dialyzer beta(2)-microglobulin kinetics with the two most common causes of deaths: Cardiac and infectious diseases. Cox regression analyses were performed to relate cardiac or infectious deaths to cumulative mean follow-up predialysis serum beta(2)-microglobulin levels while controlling for baseline demographics, comorbidity, residual kidney function, and dialysis-related variables. RESULTS The cohort of 1813 patients experienced 180 infectious deaths and 315 cardiac deaths. The adjusted hazard ratio for infectious death was 1.21 (95% confidence interval 1.07 to 1.37) per 10-mg/L increase in beta(2)-microglobulin. This association was independent of the prestudy years on dialysis. In contrast, the association between serum beta(2)-microglobulin level and cardiac death was not statistically significant. In similar regression models, higher cumulative mean Kt/V of beta(2)-microglobulin was not significantly associated with either infectious or cardiac mortality in the full cohort but exhibited trends suggesting an association with lower infectious mortality (relative risk 0.93; 95% confidence interval 0.86 to 1.01, for each 0.1-U increase in beta(2)-microglobulin Kt/V) and lower cardiac mortality (relative risk 0.93; 95% confidence interval 0.87 to 1.00) in the subgroup with >3.7 prestudy years of dialysis. CONCLUSIONS These results generally support the notion that middle molecules are associated with systemic toxicity and that their accumulation predisposes dialysis patients to infectious deaths, independent of the duration of maintenance dialysis.

Bias in Assessment of Health-Related Quality of Life in a Hemodialysis Population: A Comparison of Self-Administered and Interviewer-Administered Surveys in the HEMO Study

ABSTRACT. Examined is the relationship of patient-reported health-related quality of life (HRQOL) to the mode of survey administration in the Hemodialysis Study. In addition to self-administered surveys to assess HRQOL, interviewer-administered surveys were made available to include patients with poor vision, decreased manual dexterity, or strong preference. For examining the predictors of participation by self-administration of the survey, multiple logistic regression was performed. For examining the relationship of HRQOL results to mode of survey administration, adjusted differences between the self-administered and interviewer-administered groups were obtained from multiple linear regression models accounting for sociodemographic and case-mix factors. A total of 978 of the first 1000 subjects in the Hemodialysis Study completed the survey by interview (n = 427) or by self-administration (n = 551). The interviewer-administered group was older, was more likely black, had longer duration of ESRD, had a higher prevalence of diabetes, and had more severe comorbidity (all P < 0.01). After adjustment for these differences, patients in the interviewer-administered group had higher scores on scales that measured Role-Physical, Role-Emotional, and Effects of Kidney Disease (all P < 0.001). Dialysis studies that restrict HRQOL measurement to patients who are able to complete surveys without assistance will not accurately represent the health of the overall hemodialysis population. Clinical studies and clinical practices using HRQOL as an outcome should include interviewer administration or risk a selection bias against subjects with older age, minority status, and higher level of comorbidity. Future investigation should include research of survey modalities with a low response burden such as telephone interview, computer-assisted interview, and proxy administration.

The Relationship of Age, Race, and Ethnicity with Survival in Dialysis Patients

BACKGROUND AND OBJECTIVES Reports on the racial and ethnic differences in dialysis patient survival rates have been inconsistent. The literature suggests that these survival differences may be modified by age as well as categorizing white race as inclusive of Hispanic ethnicity. The goal of this study was to better understand these associations by examining survival among US dialysis patients by age, ethnicity, and race. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Between 1995 and 2009, 1,282,201 incident dialysis patients ages 18 years or older were identified in the United States Renal Data System. Dialysis survival was compared among non-Hispanic blacks, non-Hispanic whites, and Hispanics overall and stratified by seven age groups. RESULTS The median duration of follow-up was 22.3 months. Compared with non-Hispanic whites, a lower mortality risk was seen in Hispanics in all age groups. Consequently, when Hispanic patients were excluded from the white race, the mortality rates in white race all increased. Using non-Hispanic whites as the reference, a significantly lower mortality risk for non-Hispanic blacks was consistently observed in all age groups above 30 years (unadjusted hazard ratios ranged from 0.70 to 0.87; all P<0.001). In the 18- to 30-years age group, there remained an increased mortality risk in blacks versus non-Hispanic whites after adjustment for case mix (adjusted hazard ratio=1.19, 95% confidence interval=1.13-1.25). CONCLUSIONS The mortality risk was lowest in Hispanics, intermediate in non-Hispanic blacks, and highest in non-Hispanic whites. This pattern generally holds in all age groups except for the 18- to 30-years group, where the adjusted mortality rate for non-Hispanic blacks exceeds the adjusted mortality rate of non-Hispanic whites.

The associations between race and geographic area and quality-of-care indicators in patients approaching ESRD.

BACKGROUND AND OBJECTIVES Pre-ESRD care is an important predictor of outcomes in patients undergoing long-term dialysis. This study examined the extent of variation in receiving pre-ESRD care and black-white disparities across urban and rural counties. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Participants were 404,622 non-Hispanic white and black patients aged >18 years who began dialysis between 2005 and 2010 and resided in 3076 counties from the U.S. Renal Data System. The counties were grouped into large metropolitan, medium/small metropolitan, suburban, and rural counties. Pre-ESRD care indicators included receipt of nephrologist care at least 6 or 12 months before ESRD, dietitian care, use of arteriovenous fistula at first outpatient dialysis session, and use of erythropoiesis-stimulating agents (ESAs) in patients with hemoglobin level < 10 g/dl. RESULTS Large metropolitan and rural counties had lower percentages of patients who received pre-ESRD nephrologist care (25.7% and 26.9% for nephrologist care > 12 months), compared with the higher percentage in medium/small metropolitan counties (31.6%; both P<0.001). For both races, nonmetropolitan patients had poorer access to dietitian care and lower ESA use than metropolitan patients. Consistently in all four geographic areas, black patients received less care than their white counterparts. The unadjusted odds ratios of black versus white patients in receiving nephrologist care for >12 months before ESRD were 0.66 (95% confidence interval [CI], 0.61-0.72) in large metropolitan counties and 0.79 (95% CI, 0.69-0.90) in rural counties. The patterns remained, albeit attenuated, after adjustment for patient factors. CONCLUSIONS The receipt of pre-ESRD care, with blacks receiving less care, varies among geographic areas defined by urban/rural characteristics.

Enhancing Diabetes Self-care Among Rural African Americans With Diabetes Results of a Two-year Culturally Tailored Intervention

Purpose The purpose of this study is to test the feasibility of conducting a community-based randomized controlled trial evaluating a culturally tailored community-based group diabetes self-management education (DSME) program among rural African Americans. Methods Thirty-two African American rural adults with type 2 diabetes were recruited and 25 adults were retained and participated in an interventional study designed to test the effectiveness of the “Taking Care of Sugar” DSME program for the 2-year follow-up. Participants were selected from rural central Virginia. Primary outcomes variables included average blood sugar levels, cardiovascular risk factors, and general physical and mental health. These outcomes were assessed at baseline, 3 months, 6 months, and 12 months post baseline. Results From baseline to 3-month follow-up assessment, participants exhibited significant improvement on several physiological and behavioral measures. Given the small sample size, hypothesis testing was limited. Results show change from baseline over time, illustrating that the primary outcome of A1C decreased, although not significant. Additionally, participants reported more knowledge about diabetes self-management and personal care skills (ie, exercise and foot care) that persisted over time. The feasibility of the culturally tailored DSME was established, and participation with the program was high. Conclusions A community-based group DSME program using storytelling is feasible. This research will help to inform clinicians and health policymakers as to the types of interventions that are feasible in a larger rural population. If such a program is carried out, we can improve knowledge, reduce complications, and improve quality of life among rural African Americans.