Table 6. Final model of factors associated with reporting influenza-like illness, New South Wales, Australia, July–September 2009*.

Factor, n = 2,431 respondents	Prevalence of factor, % (95% CI)	Reference category†	Relative risk (95% CI)	p value‡
Age, y		>65 y
16–34	26.0 (23.2–28.8)		4.74 (2.38–9.45)	<0.001
35–49	21.7 (19.4–23.9)		3.25 (1.68–6.26)	<0.001
50–64	17.7 (16.1–19.3)		2.60 (1.36–4.99)	0.004
Female sex	50.5 (47.8–53.2)	Male	1.25 (0.76–2.05)	0.375
Daily smoker	13.0 (10.8–15.1)	Occasional/ex-/nonsmoker	1.90 (1.10–3.26)	0.021
Body mass index
Obese	18.0 (15.9–20.1)	Healthy or underweight	2.32 (1.30–4.16)	0.005
Overweight	28.6 (26.3–31.0)	Healthy or underweight	1.20 (0.68–2.12)	0.534

*Influenza-like illness defined as fever with cough and fatigue. Some questions are only collected on selected age groups, so sample sizes vary. 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 body mass index 5.2%; smoking status 0.1%.
‡Statistically significant results at the 5% level are in boldface.