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Volume 17, Number 7—July 2011

Research

Epidemiology of Influenza-like Illness during Pandemic (H1N1) 2009, New South Wales, Australia

David J. MuscatelloComments to Author , Margo Barr, Sarah V. Thackway, and C. Raina MacIntyre
Author affiliations: Author affiliations: New South Wales Department of Health, North Sydney, New South Wales, Australia (D.J. Muscatello, M. Barr, S. Thackway); University of New South Wales, Kensington, New South Wales, Australia (D.J. Muscatello, C.R. MacIntyre); University of Wollongong, Wollongong, New South Wales, Australia (M. Barr)

Main Article

Table 5

Risk factors evaluated for influenza-like illness, New South Wales, Australia, July–September 2009*

Factor Factor prevalence, % (95% CI) Reference category† Age group analyzed (no. respondents)‡ Relative risk
(95% CI) p value§
Age, y >65 y All ages (2,909)
0–15 21.4 (19.4–23.5) 5.96 (3.25–10.93) <0.001
16–34 26.0 (23.2–28.8) 4.76 (2.35–9.62) <0.001
35–49 21.7 (19.4–23.9) 3.55 (1.86–6.79) <0.001
50–64
17.7 (16.1–19.3)


3.00 (1.57–5.71)
0.001
Female sex¶
50.5 (47.8–53.2)
Male
All ages (2,909)
1.31 (0.89–1.94)
0.173
Rural region¶ 29.9 (28.4–31.4) Urban All ages (2,909) 1.26 (0.87–1.84) 0.227
Socioeconomically disadvantaged¶ #
38.4 (35.9–40.9)
Not disadvantaged
All ages (2,909)
0.93 (0.63–1.38)
0.729
>2 children in household¶ 34.5 (31.9–37.2) <2 children residing in household All ages (2,909) 0.75 (0.51–1.10) 0.142
>3 persons in household¶
67.7 (65.6–69.7)
1–2 persons in household
All ages (2,909)
1.14 (0.75–1.72)
0.536
Seasonal influenza vaccination in past 12 mo¶ 25.6 (23.5–27.7) No seasonal influenza vaccination in past 12 mo >6 mo (2,888) 0.80 (0.49–1.31) 0.372
Current asthma¶
11.4 (9.8–13.0)
No current asthma
>2 y (2,831)
1.15 (0.69–1.92)
0.595
Body mass index¶ >2 y (2,831)
Obese 18.0 (15.9–20.1) Healthy or underweight 2.14 (1.31–3.48) 0.002
Overweight
28.6 (26.3–31.0)
Healthy or underweight

1.06 (0.67–1.67)
0.816
Current diabetes or high blood glucose¶ 8.0 (6.7–9.2) No current diabetes or high blood glucose >9 y (2,636) 0.97 (0.50–1.91) 0.936
Daily smoker¶ 13.0 (10.8–15.1) Occasional/ex-/non-smoker >16 y (2,431) 1.94 (1.06–3.54) 0.031
Inadequate physical activity¶ 48.6 (45.6–51.7) Adequate physical activity >16 y (2,431) 1.04 (0.65–1.65) 0.881
Risky alcohol drinking¶
31.6 (28.6–34.7)
Low-risk alcohol drinking
>16 y (2,431)
1.25 (0.76–2.05)
0.378
High or very high psychological distress score¶
11.2 (9.4–13.1)
Moderate or low psychological distress score
>16 y (2,431)
1.41 (0.85–2.35)
0.182
Pneumococcal vaccination in past 5 y¶ 28.3 (25.7–30.9) No pneumococcal vaccination in the past 5 y (adjusted for age) >50 y (1,633) 1.20 (0.56–2.56) 0.640

*CI, confidence interval.
†Not stated and “Don’t know” responses were included in the reference category. Among parameters with any such responses, the proportions were index of socioeconomic disadvantage 0.9%, vaccinated against influenza in the past 12 mo 1.0%, current asthma 0.3%, body mass index 5.2%, smoking status 0.1%, psychological distress score 3.0%, alcohol use 1%, and pneumococcal vaccination 7.0%.
‡Some questions are only collected on selected age groups, so sample sizes vary.
§Significant results at the 5% level are in boldface.
¶Adjusted for age.
#Disadvantaged = lowest 2 quintiles of the Australian index of relative socioeconomic disadvantage based on the respondent's residential postcode; not disadvantaged = upper 3 quintiles.

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