CHAPTER 12 CARDIOVASCULAR MORTALITY OF PATIENTS WHO COMMENCE DIALYSIS WITHOUT CLINICAL EVIDENCE OF CARDIOVASCULAR DISEASE

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1 CHPTER CRDIOVSCULR MORTLITY OF PTIENTS WHO COMMENCE DILYSIS WITHOUT CLINICL EVIDENCE OF CRDIOVSCULR DISESE Matthew Roberts Kevan Polkinghorne Stephen McDonald Francesco Ierino

2 CRDIOVSCULR MORTLITY NZDT Registry 07 Report INTRODUCTION Patients on dialysis experience a heavier burden of cardiovascular disease (CVD) and a markedly increased risk of death compared to the general population. The aim of this analysis was to quantify the cardiovascular mortality rate of patients receiving dialysis who have no clinical evidence of CVD, and compare this to the general population. Secondary aims were to examine the influence of baseline characteristics on this cardiovascular mortality, and to compare changes in mortality rates over time between the general population and patients receiving dialysis. METHODS dult patients who commenced dialysis between 99 and 0 were followed to the end of 03. Patients with no known CVD when they commenced dialysis were defined as having no known or suspected coronary artery disease, peripheral vascular disease or cerebrovascular disease. The outcome of interest was cardiovascular death defined according to NZDT Codes (Figures. and.) and the broadest corresponding International Classification of Diseases codes in the general population data, so as to obtain the most conservative match (Figure.). The 9 th Revision (ICD-9) was used until 996 (999 for patients in New Zealand) and the th Revision (ICD-) thereafter. General population data was obtained from the ustralian ureau of Statistics, Statistics New Zealand and the New Zealand Health Information Service. Patients entered the analysis on the date of their first dialysis and were analysed until the date of cardiovascular death with censoring at () death from a non cardiovascular cause, () first renal transplant, (3) return of native kidney function, or (4) loss to follow up. -specific mortality rates were calculated and standardised mortality ratios () derived using the data from the general population. Figure. Cardiovascular Death Defined by the NZDT ICD-9 and ICD- Codes Outcomes NZDT ICD-9 ICD- Cardiovascular -, 4-7, 40, 404, 4-44 I, I3, I-, I30- Death 6, , , 44, 7 I, I60-I69, I7, K Figure. Specific Causes of the Cardiovascular Deaths in the NZDT Cohort Deaths in patients who receive a kidney transplant are not included Code Cause of death ustralia New Zealand, Myocardial infarction 67 (46%) 47 (4%) 6 Cardiac arrest 44 (9%) 4 (8%) Cerebrovascular accident 44 (%) 93 (%),, 7 Heart failure 73 (8%) 47 (%) 8 owel infarction 7 (3%) (%) 6 ortic aneurysm - rupture 36 (%) 7 (<%) 4 Haemorrhagic pericarditis 7 (<%) 0 Total

3 NZDT Registry 07 Report CRDIOVSCULR MORTLITY RESULTS During the study period, 8,3 patients were eligible for inclusion with 4,34 person years of follow up. There were 8,7 deaths from any cause during the study period. t their last survey, 4,90 were residing in ustralia and 3, in New Zealand. lmost half of the patients had known or suspected CVD at the time of commencing dialysis (Figure.3). The prevalence of baseline CVD was greater in the 4-4 year age group in New Zealand compared to ustralia (Figure.4). There were substantial differences between ustralian and New Zealand patients with respect to ethnicity, prevalence of diabetes and initial mode of dialysis (Figure.). ecause of these differences, separate analyses were performed for each country. Figure.3 Proportion of Patients with Coronary rtery Disease Peripheral Vascular Disease, Cerebrovascular Disease or any One of These Proportion ustralia Coronary rtery Disease Cerebrovascular Disease New Zealand Peripheral Vasc. Disease ny Vascular Disease Figure.4 Distribution of Patients Receiving Dialysis ccording to aseline CVD Status % No CVD us NZ 97% 96% 89% 89% 79% 77% 64% % 46% 4% 34% 33% 30% 30% 36% 0% >= Number without CVD Number with CVD ustralia New Zealand -3

4 CRDIOVSCULR MORTLITY NZDT Registry 07 Report USTRLI Cardiovascular disease was responsible for % of deaths (Figure.). The age-specific cardiovascular mortality rate for patients without CVD at baseline was.3 (9% confidence interval:.9-.8) per 0 person years in those aged 3 to 44 years and increased to.9 (.-3.) per 0 person years in those aged 7 to 84 (Figure.6 ). Respectively, these patients were (98-49) and.7 (.0-6.4) times more likely to die a cardiovascular death than people of similar age in the general population (Figure.6 ). Even in patients with no CVD and no diabetes, the cardiovascular mortality rate was almost 0 times that of the general population in younger patients (Figure.7). The age-specific mortality rates were similar for men and women but women had substantially greater age-specific s (Figure.8). Results were similar for the individual causes of death with the exception of death due to cardiac arrest. Younger patients without known CVD commencing dialysis had a thousand-fold, not hundred-fold, increased risk of death due to cardiac arrest than younger people in the general population (Figure.9). There has been a steady decline in the CVD mortality rates, particularly in people aged over 6 years, in the general population. There was no evidence that patients on dialysis experienced a comparable decline in cardiovascular mortality (Figure.). In fact, CVD mortality rates may even be rising in the 4-4 year age group. NEW ZELND Cardiovascular disease was responsible for % of deaths (Figure.). The findings in New Zealand patients were similar to the ustralian patients overall and with respect to the main outcome of cardiovascular death (Figure.). The cardiovascular mortality rates were slightly higher in both dialysis and general populations. The age-specific cardiovascular mortality rate for patients without CVD as baseline was 3.4 (.4-4.9) per 0 person years in those aged 3 to 44 years and increased to.9 (8.-9.) per 0 person years in those aged 7 to 84. Respectively, these patients were 3 (9-86) and.3 ( ) times more likely to die a cardiovascular death than people of similar age in the general population. Other specific comparisons were also similar to the ustralian data but confidence intervals were wider. DISCUSSION lmost half of all patients commencing dialysis over a twelve-year period had some form of cardiac or vascular disease, indicating the substantial development of CVD prior to the need for dialysis. Patients without known cardiac or vascular disease experienced a cardiovascular mortality rate to 0 times that of people in the general population, depending on their age, and over 00 times higher for death from cardiac arrest in younger patients. These high cardiovascular mortality rates reinforce the need for intensive management of CVD risk factors in the pre-dialysis phase and to develop strategies for the identification and treatment of clinically silent CVD in patients starting dialysis. Figure. Characteristics at First Dialysis in ustralian and New Zealand Patients Divided ccording to the Presence or bsence of Cardiovascular Disease (CVD) ustralia New Zealand No CVD (n=7,909) CVD (n=6,993) P No CVD (n=,683) CVD (n=,8).3 ( ) 66.0 ( ) < ( ) 6. ( ) <0.00 Male 433 (%) 4 (60%) < (%) 946 (6%) <0.00 Diabetes 364 (7%) 3070 (44%) < (8%) 9 (60%) <0.00 Haemodialysis 943 (7%) 4948 (7%) < (7%) 836 (%) 0.3 Race <0.00 <0.00 Caucasoid 636 (80%) 807 (83%) 86 (%) 688 (4%) TSI 693 (9%) 97 (9%) - - Maori 44 (<%) (<%) 484 (9%) 76 (38%) Pacific (%) 9 (%) 6 (3%) 88 (%) TSI = boriginal or Torres Strait Islander P -4

5 NZDT Registry 07 Report CRDIOVSCULR MORTLITY In the following (Figures.6-.9 and.), panel shows the age-specific cardiovascular mortality rates and panel the age-specific standardised mortality ratio for cardiovascular death. Figure.6 ustralian Patients Stratified by the Presence of Clinically Evident CVD No CVD CVD ll Figure.7 ustralian Patients Without Clinically Evident CVD Stratified by the Presence of Diabetes No Diabetes Diabetes Figure.8 ustralian Patients Without Clinically Evident CVD Stratified by Gender Female Male -

6 CRDIOVSCULR MORTLITY NZDT Registry 07 Report Figure.9 Sudden Cardiac Deaths in ustralian Patients Stratified by the Presence of Clinically Evident CVD No CVD CVD ll Figure. Cardiovascular Mortality Rates from in the General ustralian Population and Dialysis Population 3 Deaths per 0 person years Deaths per 0 person years Year Era 3-44y 4-4y -64y 6-74y 7-84y () The General ustralian Population () ustralian patients commencing dialysis between 99 and 0 Figure. New Zealand Patients Stratified by the Presence of Clinically Evident CVD No CVD CVD ll -6