SAT-201 ASSOCIATION BETWEEN SMOKING AND ALL-CAUSE AND CAUSE- SPECIFIC MORTALITY IN INCIDENT DIALYSIS PATIENTS-AN ANZDATA REGISTRY ANALYSIS

Abstract

Smoking increases all-cause mortality and development of cardiovascular disease in patients with end-stage kidneydisease(1). No study to date has examined prevalence and outcomes amongst smokers in Australian and New Zealand dialysis patients. The aims of this study were to explore the prevalence of smoking in incident patients commencing dialysis and to evaluate the effect of smoking at commencement of dialysis on subsequent all-cause and cardiovascular mortality. We conducted a cohort study using the ANZDATA Registry (1990-2016) to explore the association of smoking status at commencement of renal replacement therapy (RT) with all cause and cardiovascular mortality in Australian and New Zealand. Inclusion criteria were adults (18 years or older) at commencement of renal replacement therapy (RRT) for >3 months. Patients who started with a transplant (pre-emptive) were excluded. Incidence of death was estimated by using survival analysis. In the final model of time to all-cause mortality, we adjusted for age, aboriginal, mode of dialysis, BMI, diabetes, history of chronic lung disease, history of coronary artery disease, history of perivascular disease and time dependent transplant status. The hazard ratios of death of current smokers versus non-smokers and former smokers and the 95% confidence interval was calculated from the adjusted model and a Kaplan Meier survival curves of commencement of dialysis until death were constructed. A total of 57838 patients commenced dialysis during 1990-2016, of whom 56512 individuals had data on smoking history: the mean age was 59.0 years, 45.6% reported they were non-smokers, 40.8% were former smokers and 13.6% current smokers. Forty-one % were female, 43% had diabetes, 29.2 % were obese, 38.5% were>65 years of age and 7.5% were Aboriginal and Torres Strait Islanders. During the median followup of 4.4 years with a mean of 6.1 years, 33547 died (59.4%), 13140 (23.3%) underwent a kidney transplant without lost to follow-up. Cardiovascular disease was the major cause of death, reported in 15174 (45.2% of deaths), 9.739 (17.2% of deaths ) died of a malignancy, 66 (0.1% of deaths) died of infection related cause and 301 (0.5% of deaths) died of respiratory failure and 5185 (9.2%) had a cancer diagnosis. Hazard ratio of all cause-mortality for smokers was 1.13 (95%CI :1.10-1.15, p<0.0001). Similarly smokers had a higher rate of death due to cardiovascular disease ( HR 1.16; 95% CI 1.12-1.20, p < 0.0001). In addition, smoking history was significantly associated with a higher rate of diagnosis of cancer (HR 1.26; 95% CI 1.19-1.33, p< 0.0001), infections ( HR 1.07; 95% CI 1.06-1.09, p<0.0001) and respiratory failure ( HR 1.06; 95% CI 1.05-1.07, p< 0.001). The death due to infections rate is higher for smokers but this is not significant ( HR 1.37; 95% CI 0.83,2.26, p=0.22) The cumulative incidence of death among smokers and non- smokers were 63.1% for smokers and 54.9% for non-smokers. Amongst patients commencing dialysis in Australia and New Zealand, 54% were either current or former smokers. Smoking history was an independent risk factor for all-cause mortality, cardiovascular mortality, diagnosis of cancer and respiratory failure. Smoking is an important risk factor and the patients should be encouraged to quit