Web Table.

Parapneumonic empyema-related hospitalizations by associated pathogens, United States 1996–2008

Age group and empyema group	Number, 2008	Rate per 100000, 2008 (95% CI)	Rate difference£ (95% CI)	Rate ratio£ (95% CI)	Test for trend, p
Less than 18 years old
Pneumococcal	507	0.68 (0.51–0.91)	0.07 (−0.17 – 0.43)	1.1 (0.7–1.7)	0.093
Streptococcal (non-pneumococcal)	231	0.31 (0.21–0.46)	0.20 (0.05 – 0.46)	2.7 (1.5–5)	<0.001
Staphylococcal	291	0.39 (0.28–0.54)	0.23 (0.06 – 0.51)	2.4 (1.4–4.1)	<0.001
Other/Unknown	1293	1.74 (1.35–2.23)	1.03 (0.52 – 1.76)	2.5 (1.7–3.5)	<0.001
18–39 years
Pneumococcal	322	0.35 (0.28–0.44)	0.08 (−0.03 – 0.24)	1.3 (0.9–1.9)	0.102
Streptococcal (non-pneumococcal)	238	0.26 (0.19–0.35)	0.07 (−0.04 – 0.25)	1.4 (0.8–2.3)	<0.001
Staphylococcal	466	0.51 (0.4–0.64)	0.39 (0.19 – 0.72)	4.2 (2.5–7)	<0.001
Other/Unknown	1358	1.48 (1.3–1.68)	0.58 (0.3 – 0.93)	1.6 (1.3–2)	<0.001
40–64 years
Pneumococcal	924	0.93 (0.8–1.08)	0.15 (−0.06 – 0.41)	1.2 (0.9–1.5)	0.205
Streptococcal (non-pneumococcal)	952	0.96 (0.82–1.12)	0.42 (0.19 – 0.72)	1.8 (1.3–2.3)	<0.001
Staphylococcal	1197	1.21 (1.05–1.38)	0.90 (0.56 – 1.36)	3.9 (2.8–5.4)	<0.001
Other/Unknown	4969	5.01 (4.66–5.38)	2.68 (2.05 – 3.4)	2.2 (1.9–2.5)	<0.001
65 or more years
Pneumococcal	518	1.33 (1.08–1.64)	–0.36 (−0.71 – 0.12)	0.8 (0.6–1.1)	0.041
Streptococcal (non-pneumococcal)	571	1.47 (1.21–1.79)	0.72 (0.3 – 1.31)	2.0 (1.4–2.7)	<0.001
Staphylococcal	954	2.46 (2.12–2.85)	1.53 (0.89 – 2.37)	2.6 (2–3.5)	<0.001
Other/Unknown	3404	8.77 (8.06–9.55)	4.04 (2.77 – 5.52)	1.9 (1.6–2.2)	<0.001

^£Rate difference and rate ratios compared 2008 and 1996 rates. Test for trends included all study years, 1996–2008.