Cardiovascular Outcomes In Hemodialysis Patients Research Articles

Antihypertensive Medication Exposure and Cardiovascular Outcomes in Hemodialysis Patients

Background/Aims: Our understanding of the effectiveness of cardioprotective medications in maintenance dialysis patients is based upon drug exposures assessed at a single point in time. We employed a novel, time-dependent approach to modeling medication use over time to examine outcomes in a large national cohort. Methods: We linked Medicaid prescription claims with United States Renal Data System registry data and Medicare claims for 52,922 hypertensive maintenance dialysis patients. All-cause mortality and a combined cardiovascular disease (CVD)-endpoint were modeled as functions of exposure to cardioprotective antihypertensive medications (renin angiotensin system antagonists, β-adrenergic blockers, and calcium channel blockers) measured with three time-dependent covariates (weekly exposure status, proportion of prior weeks with exposure, and number of switches in exposure status) and with propensity adjustment. Results: Current cardioprotective medication exposure status as compared to not exposed was associated with lower adjusted hazard ratios (AHRs) for mortality, though the magnitude depended upon the proportion of prior weeks with medication (duration) and the number of switches between active and non-active use (switches) (AHR range 0.54-0.90). Combined CVD-endpoints depended upon the proportion of weeks on medication: AHR = 1.18 for 10% and AHR = 0.90 for 90% of weeks. Combined CVD-endpoint was also lower for patients with fewer switches. Conclusions: Effectiveness depends not only on having a drug available but is tempered by duration and stability of use, likely reflecting variation in clinical stability and patient behavior.

Impact of Sleep Quality on Cardiovascular Outcomes in Hemodialysis Patients: Results from the Frequent Hemodialysis Network Study

Background: Poor sleep quality is a common, persistent, and important problem to patients with end-stage renal disease (ESRD). This report examines whether sleep quality is associated with dialysis treatment factors and other modifiable clinical factors in a large group of hemodialysis (HD) patients. Methods: Cross-sectional analyses were conducted on baseline data collected from participants in the Frequent Hemodialysis Network trials. Sleep quality was measured using the Medical Outcomes Study Sleep Problems Index II (SPI II), a 9-item measure of sleep quality with higher scores reflecting poorer sleep quality. Results: The participants had an age of 51.2 ± 13.6 years, 61% were male, 38% were black, and 42% had diabetes. Higher pre-dialysis serum phosphorus (per 0.5 mg/ml) (OR 0.91; 95% CI 0.85, 0.96) and depression (OR 0.16; 95% CI 0.10, 0.25) were independently associated with decrements in sleep quality. There was also a difference in time to recovery from dialysis for the fourth versus the first SPI II quartile (5.1 h; p < 0.0001). Conclusion: These findings underscore the link between sleep and daytime function and suggest that improving sleep may provide an opportunity to improve outcomes in ESRD. Whether sleep problems may be improved by reduction of serum phosphorus or treatment of depression in the HD population merits further investigation.

Impact of Diabetes on Cardiovascular Outcomes in Hemodialysis Patients Undergoing Coronary Revascularization

Among hemodialysis (HD) patients, those who have diabetes have poorer cardiovascular outcomes than non-diabetic patients, but the impact of diabetes on cardiovascular outcomes has not been fully elucidated in HD patients undergoing coronary revascularization. We identified 375 HD patients (203 diabetes, 172 non-diabetes) and 9,006 patients without HD (3,455 diabetes, 5,551 non-diabetes) in the database of the CREDO-Kyoto registry of patients undergoing their first coronary revascularization. In non-HD patients, significantly higher risks of death (10.8% vs. 7.7%, P < 0.0001; adjusted hazard ratio (HR) 1.29, P < 0.0001) and major adverse cardiovascular events (MACE), a composite of death, myocardial infarction and stroke (18.8% vs. 13.3%, P < 0.0001; HR 1.36, P < 0.0001) were seen in diabetic patients than in non-diabetic patients through 4-year follow-up. Analysis in HD patients showed that the duration of HD before first coronary revascularization was significantly shorter in diabetic patients than in non-diabetic patients (median interval: 858 vs. 2,216 days, P < 0.0001). In contrast to the results in non-HD patients, the risks of death (41.9% vs. 39.1%, P=0.75; HR 0.98, P=0.93) and MACE (45.6% vs. 45.8%, P=0.83; HR 0.87, P=0.50) after first revascularization were comparable between diabetic and non-diabetic HD patients. There were significant interactions between HD and diabetes for death and for MACE. HD patients who require coronary revascularization have extremely poor outcomes irrespective of concomitant diabetes.

Influence of Hypertension on Cardiovascular Outcomes in Hemodialysis Patients

Cardiovascular disease is a leading cause of morbidity and mortality in chronic hemodialysis patients. Most patients with chronic kidney disease have hypertension and its prevalence remains high following renal replacement therapy. Early studies suggested that hypertension was a risk factor for total and cardiovascular mortality in chronic hemodialysis patients, but the results of more recent studies have caused experts to question these assertions. Systolic hypertension, widened pulse pressure, and nondipping may be better predictors of mortality compared to diastolic hypertension or increased mean arterial pressure. Hypertension in hemodialysis patients is a risk factor for left ventricular hypertrophy (LVH), diastolic dysfunction, and congestive heart failure; good blood pressure control may promote its regression. Atherosclerosis and ventricular arrhythmias may also be linked to hypertension. Thus blood pressure control with a focus on systolic pressure appears to be a prudent strategy to improve cardiovascular outcomes in hemodialysis patients.

Response of Homocysteine, Cystathionine, and Methylmalonic Acid to Vitamin Treatment in Dialysis Patients

Hyperhomocysteinemia is observed in >80% of hemodialysis patients and is considered a risk factor for cardiovascular disease. Vitamin treatment lowers total homocysteine (tHcy) concentrations in plasma and may therefore reduce the associated risk. Current treatment strategies have not achieved normalization of tHcy in the majority of dialysis patients. We administered folic acid (5 mg) plus vitamin B(6) (50 mg) and B(12) (0.7 mg) intravenously to 38 hyperhomocysteinemic patients (tHcy >18 micromol/L) after each dialysis treatment. The treatment phase lasted 1 month, and serum concentrations of tHcy, methylmalonic acid (MMA), and cystathionine were measured at weeks 0, 2, 4, 6, 8, and 24. The median serum tHcy concentration decreased significantly, from 26.1 micromol/L at baseline to 13.2 micromol/L at week 4. The median change in tHcy after 4 weeks was 13.4 micromol/L (-51%) compared with baseline. Serum MMA and cystathionine concentrations were reduced by 28% and 26%, respectively, but neither was normalized at 4 weeks. Backward-elimination stepwise regression analysis revealed that higher concentrations of tHcy, MMA, and cystathionine and lower folate at baseline predict changes of tHcy after treatment. Twenty weeks after vitamin withdrawal, tHcy concentrations returned to values comparable to baseline (median, 24.8 micromol/L). The combination of folic acid, vitamin B(12), and vitamin B(6) used in this study normalized serum concentrations of tHcy in almost all of our hyperhomocysteinemic dialysis patients. This regimen may be used to investigate the effects of homocysteine normalization on cardiovascular outcomes in hemodialysis patients.

Hyperhomocysteinemia predicts cardiovascular outcomes in hemodialysis patients

We prospectively tested the prediction power of homocysteinemia for all-cause and cardiovascular outcomes in a cohort of 175 hemodialysis patients followed for 29 +/- 12 months. Survival analysis was performed by the Cox's proportional hazard model and data were expressed as hazard ratio and 95% confidence interval (CI). During the follow-up period 51 patients died, 31 of them (61%) of cardiovascular causes and 16 patients developed non-fatal atherothrombotic complications. Plasma total homocysteine was an independent predictor of cardiovascular mortality (P=0.01). Combined analysis of fatal and non-fatal atherothrombotic events showed that homocysteine was a strong and independent predictor of these outcomes because the risk of these events was 8.2 times higher (95% CI 1.9 to 32.2) in patients in the third homocysteine tertile than in those in the first tertile (P=0.005). There is a clear association between hyperhomocysteinemia and incident cardiovascular mortality and atherothrombotic events in hemodialysis patients. Intervention studies are needed to determine whether the accumulation of this substance has a causal role in the pathogenesis of cardiovascular damage in patients undergoing hemodialysis.