Pages

Sunday, November 4, 2012

Afib Rising in Dialysis Patients

MedPage Direct Link


Atrial fibrillation onset soon after starting dialysis has risen over the past decade, although the high mortality risk associated with the comorbidity has been falling, a national analysis showed.
Incidence of the arrhythmia in this population rose 11% from 1995 through 2007, Wolfgang C. Winkelmayer, MD, ScD, of Stanford University in Palo Alto, Calif., and colleagues found.
Mortality after incident Afib fell 22% from 1995 through 2008, but was still high at more than 50% in the first year after diagnosis, they reported online in Circulation: Journal of the American Heart Association.
"While it is nice to see a decline in mortality after Afib, it is unclear what contributed to this positive trend," the group wrote, noting that without warfarin use data "we were unable to study whether trends towards better outcomes could be explained by higher rates of oral anticoagulation."
Poor kidney function is an independent risk factor for Afib incidence, which may help explain why the prevalence of Afib among seniors on hemodialysis tripled over the prior decade.
"Given the specific circumstances of chronic dialysis treatment, it is likely that factors that are specific to the dialysis population are operational and responsible for much of this excess Afib incidence compared with the general population," for whom Afib incidence has remained stable, Winkelmayer's group suggested.
Periodic swings in fluids and electrolytes from the typical three relatively short dialysis sessions per week may lead to neurohormonal activation and cardiac remodeling in these patients with chronic inflammation, oxidative stress, and positive calcium balances.
"All these factors contribute to excess (vascular and valvular) calcification and chronic fluid overload, leading to chronic stress and wear to an overfilled and increasingly stiff cardiovascular system," the group pointed out.
Their analysis of the U.S. Renal Data System included all patients ages 67 or older starting chronic dialysis from 1995 through 2007 for whom Medicare data showed no atrial fibrillation or flutter in the prior 2 years.
Among the more than 250,000 patients followed in the analysis, 29% developed Afib before death or kidney transplantation with a rate of 148 per 1,000 person-years.
Onset within the first year of dialysis rose over time from a rate of 11% in 1995 to 15% in 2007, a change that remained statistically significant in the multivariate analysis.
However, toward the end of the study period, the incidence stopped rising. It leveled off after 2003 and even declined slightly to 2007.
Ischemic strokes also declined in these patients in more recent years, "even after accounting for death as a competing risk," the researchers noted.
Since data on warfarin use were not available, the study was unable to determine whether trends towards better outcomes could be explained by higher rates of oral anticoagulation.
The overall mortality rate was 706 per 1,000 people in the analysis, while 59% of the new dialysis patients died in the first year after Afib diagnosis.
The group cautioned about use of administrative claims data, which couldn't catch undiagnosed or silent Afib and may have been affected by trends in surveillance and coding of diagnosed cases.
Nevertheless, "identifying and testing any strategies to reduce incident Afib in patients on dialysis could have a large public health impact in this vulnerable population," they concluded.
The study was supported by grants from the National Institute of Diabetes, Digestive, and Kidney Diseases.
One co-author reported consulting for Boston Scientific and Precision Health Economics.
From the American Heart Association:

No comments:

Post a Comment