• Cigarette use and cardiovascular risk in chronic kidney disease: an unappreciated modifiable lifestyle risk factor.

      Stack, Austin G; Murthy, Bhamidipati V R; Regional Kidney Centre, Department of Medicine, Letterkenny General Hospital,, Health Services Executive, County Donegal, Ireland. austin.stack@hse.ie (2012-01-31)
      Tobacco use is a major modifiable cardiovascular risk factor in the general population and contributes to excess cardiovascular risk. Emerging evidence from large-scale observational studies suggests that continued tobacco use is also an independent cardiovascular risk factor among patients with chronic kidney disease (CKD). The benefits of smoking cessation programs on improving the heath status of patients and reducing mortality are unequivocal in the general population. Despite this, there has been little effort in pursuing tobacco cessation programs in dialysis cohorts or those with lesser degrees of kidney impairment. Most of our attention to date has focused on the development of "kidney-specific" interventions that reduce rates of renal disease progression and improve dialysis outcomes. The purpose of this current review is to describe the epidemiology of tobacco use among patients with CKD, draw attention to its negative impact on cardiovascular morbidity and mortality, and finally highlight potential strategies for successful intervention. We hope that this study heightens the importance of tobacco use in CKD, stimulates renewed interest in the barriers and challenges that exist in achieving smoking cessation, and endorses the efficacy of intervention strategies and the immeasurable benefits of quitting on cardiovascular and noncardiovascular outcomes.
    • Exercise and limitations in physical activity levels among new dialysis patients in the United States: an epidemiologic study.

      Stack, Austin G; Murthy, Bhamidipati; Regional Kidney Center, Department of Medicine, Letterkenny General Hospital, Health Services Executive (HSE) West, Letterkenny, County Donegal, Ireland. Austin.Stack@hse.ie (Annals of epidemiology, 2008-12)
      Epidemiologic studies of physical activity among patients with end-stage renal disease (ESRD) are lacking. The aim of this study was to describe the patterns of physical activity among new dialysis patients in the United States.
    • The Impact of Chronic Obstructive Pulmonary Disease and Smoking on Mortality and Kidney Transplantation in End-Stage Kidney Disease.

      Kent, Brian D; Eltayeb, Elhadi E; Woodman, Alastair; Mutwali, Arif; Nguyen, Hoang T; Stack, Austin G; Regional Kidney Centre, Letterkenny General Hospital, Health Services Executive-West, Donegal, Ireland. (2012-09-07)
      Background: Chronic obstructive pulmonary disease (COPD) and tobacco use are leading causes of morbidity and mortality. The prevalence and clinical impact of COPD on mortality and kidney transplantation among patients who begin dialysis therapy is unclear. Methods: We explored the clinical impact of COPD and continued tobacco use on overall mortality and kidney transplantation in a national cohort study of US dialysis patients. National data on all dialysis patients (n = 769,984), incident between May 1995 and December 2004 and followed until October 31, 2006, were analyzed from the United States Renal Data System. Prevalence and period trends were determined while multivariable Cox regression evaluated relative hazard ratios (RR) for death and kidney transplantation. Results: The prevalence of COPD was 7.5% overall and increased from 6.7 to 8.1% from 1995-2004. COPD correlated significantly with older age, cardiovascular conditions, cancer, malnutrition, poor functional status, and tobacco use. Adjusted mortality risks were significantly higher for patients with COPD (RR = 1.20, 95% CI 1.18-1.21), especially among current smokers (RR = 1.28, 95% CI 1.25-1.32), and varied inversely with advancing age. In contrast, the adjusted risks of kidney transplantation were significantly lower for patients with COPD (RR = 0.47, 95% CI 0.41-0.54, for smokers and RR = 0.54, 95% CI 0.50-0.58, for non-smokers) than without COPD [RR = 0.72, 95% CI 0.70-0.75, for smokers and RR = 1.00 for non-smokers (referent category)]. Conclusions: Patients with COPD who begin dialysis therapy in the US experience higher mortality and lower rates of kidney transplantation, outcomes that are far worse among current smokers.
    • Survival trends of US dialysis patients with heart failure: 1995 to 2005.

      Stack, Austin G; Mohammed, Amir; Hanley, Alan; Mutwali, Arif; Nguyen, Hoang; Regional Kidney Centre, Department of Medicine, Letterkenny General Hospital,, Letterkenny, Donegal, Ireland. Austin.Stack@hse.ie (2012-01-31)
      BACKGROUND AND OBJECTIVES: Congestive heart failure (CHF) is a major risk factor for death in end-stage kidney disease; however, data on prevalence and survival trends are limited. The objective of this study was to determine the prevalence and mortality effect of CHF in successive incident dialysis cohorts. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This was a population-based cohort of incident US dialysis patients (n = 926,298) from 1995 to 2005. Age- and gender-specific prevalence of CHF was determined by incident year, whereas temporal trends in mortality were compared using multivariable Cox regression. RESULTS: The prevalence of CHF was significantly higher in women than men and in older than younger patients, but it did not change over time in men (range 28% to 33%) or women (range 33% to 36%). From 1995 to 2005, incident death rates decreased for younger men (70 years). For women, the pattern was similar but less impressive. During this period, the adjusted mortality risks (relative risk [RR]) from CHF decreased in men (from RR = 1.06 95% Confidence intervals (CI) 1.02-1.11 in 1995 to 0.91 95% CI 0.87-0.96 in 2005) and women (from RR = 1.06 95% CI 1.01-1.10 in 1995 to 0.90 95% CI 0.85-0.95 in 2005 compared with referent year 2000; RR = 1.00). The reduction in mortality over time was greater for younger than older patients (20% to 30% versus 5% to 10% decrease per decade). CONCLUSIONS: Although CHF remains a common condition at dialysis initiation, mortality risks in US patients have declined from 1995 to 2005.