Table 2 Frequency of risk factors and comorbidities for invasive pneumococcal disease (with exact 95% confidence intervals) in Western Australian Aboriginal and non-Aboriginal children <5 years, 1997–2007

Risk factors

   Chemotherapy or steroid use

14

3.2

(1.8–5.3)

4

4.8

(1.3–11.7)

   Preterm delivery

39

9.6

(6.9–12.9)

11

13.9

(7.2–23.6)

   Any risk factor^a

51

12.5

(9.5–16.1)

13

16.5

(9.1–26.5)

Comorbidities

   Congenital abnormality

29

11.2

(7.6–15.7)

2

4.3

(0.5–14.8)

   Chronic respiratory disease

25

5.7

(3.7–8.3)

7

8.3

(3.4–16.4)

   Cardiovascular disease

11

2.5

(1.3–4.5)

3

3.6

(0.7–10.1)

   Disease of nervous system

10

3.9

(1.9–7.0)

2

4.4

(0.5–15.2)

   Malignancy

8

1.9

(0.8–3.7)

1

1.3

(0.0–6.9)

   Disease of digestive system^b

5

1.9

(0.6–4.5)

1

2.2

(0.1–11.8)

   Asplenia

2

0.8

(0.1–2.8)

0

0

(0.0–7.7)

   Chronic renal failure

1

0.2

(0.0–1.3)

1

1.3

(0.0–6.9)

   Hypertension

1

0.4

(0.0–2.2)

1

2.3

(0.1–12.0)

   Anycomorbidities^a

61

23.2

(18.3–28.8)

13

26.5

(15.0–41.1)

Any risk factors or comorbidities^a

92

33.7

(28.1–39.6)

21

38.9

(25.9–53.1)