Chronic Kidney Disease: The AusDiab Study 2005

Dr Kevan Polkinghorne, Associate Professor Steven Chadban,

Professor Robert Atkins

1/7 adult Australians have early CKD

AusDiab Survey April 2001• 11,247 adults (>25yrs) chosen by census

district• Australian nation-representative sample

• 16% had evidence of kidney damage

– Proteinuria: 2.4% (300,000 people)

– GFR < 60ml/min/1.7m2 : 11.2% (1.4m people)

– Haematuria: 4 6%Chadban et al, JASN 14:S131, 2003

NSW1,515

QLD1,634

VIC1,434

TAS1,848

SA1,796

WA1,561

NT1,459

TOTAL: 11,247in 2000

6,400 followed upin 2005

Adjusted HR for all-cause mortality according to baseline risk factors

0.5

1

2

3

4

Hyper

tensio

n

Albuminu

riaIm

paire

d GFR

Smoking CVD

KDM

All-

caus

e m

orta

lity

haza

rd ra

tio

Adjusted for age, sex, total cholesterol, taking lipid-lowering medication, triglycerides and WHR

Background

• The number of new cases (incidence) of end-stage kidney disease in Australia is currently 95/million population per annum, with diabetes being the leading cause

• 30% of all new end-stage kidney disease is due to diabetes - compared with 17% in 1994

• The AusDiab study has enabled, for the first time, the opportunity to determine the rate at which new cases of chronic kidney disease emerge among Australian adults who were free from chronic kidney disease at the time of the initial survey

Objectives

• The objectives are:

• (i) to estimate the incidence (% per year) of both chronic kidney disease and early kidney damage, and

• (ii) to present the risk factors associated with these conditions.

Definitions: Impaired glomerular filtration rate

• New (incident) cases of impaired GFR were defined as:– individuals who had a normal eGFR (>60

mL/min/1.73m2) at baseline, but had an eGFR of <60 mL/min/1.73m2 at follow-up.

Definitions: Albuminuria

• New (incident) cases of albuminuria were defined as:– people who had normal albumin levels in

the urine at baseline, but had a spot urine albumin:creatinine ratio (≥2.5 mg/mmol for males and ≥3.5 mg/mmol for females) at follow-up.

Results: Impaired glomerular filtration rate

Incidence of impaired glomerular filtration rate according to sex

0.4

1.3

0.9

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Male Female Total

Category

Inci

den

ce (

% p

er

year)

Incidence of impaired glomerular filtration rate according to baseline

age

0.0 0.1 0.0 0.2

1.4

3.6

0.2 0.2

1.31.8

2.4

13.1

0.1 0.1

0.71.0

1.9

7.1

0

2

4

6

8

10

12

14

25-34 35-44 45-54 55-64 65-74 >=75

Baseline age (years)

Incid

en

ce

(%

pe

r ye

ar)

Males

Females

All

Incidence of impaired glomerular filtration rate according to baseline

glucose tolerance status

0.20.5

1.10.8

1.0

1.7

2.3

2.9

0.7 0.8

1.8 1.7

0

1

1

2

2

3

3

4

Normal IFG IGT DM

Baseline glucose tolerance status

Incid

en

ce (

% p

er

year)

Males

Females

All

Incidence of impaired glomerular filtration rate according to baseline

hypertension status

0.1

0.90.8

2.8

0.5

1.8

0

2

4

Normal BP Hypertension

Baseline hypertension status

Inci

denc

e (%

per

yea

r)

Males

Females

All

Impaired glomerular filtration rate: Age & sex adjusted risks

Impaired glomerular filtration rate

Univariate Adjusted for Age & Sex

OR 95% C.I. OR 95% C.I.Glucose tolerance status:

IFG vs normal GT 1.16 0.65 – 2.06 1.31 0.71 – 2.42IGT vs normal GT 2.72 1.98 – 3.72** 1.60 1.14 – 2.24*

1.391.73

DM vs normal GT 2.60 1.75 – 3.87** 0.91 – 2.25•Hypertension vsnormal

3.63 2.81 – 4.70** 1.29 – 2.31**

* p<0.05 ** P<0.001

Results: Albuminuria

Incidence of albuminuria according to sex

1.0

0.6

0.8

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Males Females All

Category

Incid

en

ce

(%

pe

r ye

ar)

Males

Females

All

Incidence of albuminuria according to baseline age

0.2 0.30.7

1.0

3.0

5.1

0.30.5

0.3

0.7

1.2

3.5

0.20.4 0.5

0.9

2.0

4.2

0

1

2

3

4

5

6

25-34 35-44 45-54 55-64 65-74 >=75

Age groups at baseline (years)

Incid

en

ce

(%

pe

r ye

ar)

Males

Females

All

Incidence of albuminuria according to baseline glucose tolerance status

0.81.0

1.5

3.6

0.5

2.3

0.7

2.5

0.6

1.3

1.0

3.1

0

1

2

3

4

Normal IFG IGT DM

Baseline glucose tolerance status

Incid

en

ce (

% p

er

year)

Males

Females

All

Incidence of albuminuria according to baseline hypertension status

0.5

2.2

0.4

1.2

0.5

1.7

0

1

2

3

Normal blood pressure Hypertension

Baseline hypertension status

Incid

en

ce

(%

pe

r ye

ar)

Males

Females

All

Albuminuria: Age & sex adjusted risks

Albuminuria Univariate Adjusted for Age & Sex

OR 95% C.I. OR 95% C.I.Glucose tolerance status:

IFG vs normal GT 2.25 1.40 – 3.63** 1.69 1.04 – 2.75*IGT vs normal GT 1.70 1.14 – 2.52* 1.13 0.75 – 1.70

3.181.86

DM vs normal GT 5.49 3.89 – 7.75** 2.22 – 4.56**•Hypertension vsnormal

3.67 2.81 – 4.81** 1.37 – 2.51**

* p<0.05 ** P<0.001

Key findings (1)• Every year, almost 1.0% of adults

developed chronic kidney disease manifested by a reduction in kidney function (impaired glomerular filtration rate). The risks were higher females and in older people.

• Every year almost 1.0% of adults developed evidence of kidney damage as manifested by the leakage of albumin into the urine (albuminuria). The risks were higher in males and in older people.

Key findings (2)

• Having high blood pressure increased the incidence of impaired glomerular filtration rate and albuminuria three-fold.

• Having diabetes increased the incidence of albuminuria five-fold and of developing a reduction in kidney function two-fold.