Table 1.

Baseline demographic and clinical characteristics^a,^b

	Total patients		Patients with pneumonia		Patients without pneumonia
	n	%	n	%	n	%
Sample size	135,445		28,750		106,695
Follow up period (days)c
Mean (SD)	669 (502)		311 (377)		765 (487)
Median (min–max)	573 (2–1826)		153 (2–1815)		675 (61–1826)
Year of COPD diagnosis
2006	35,131	25.9	9,323	32.4	25,808	24.2
2007	33,332	24.6	7,824	27.2	25,508	23.9
2008	28,017	20.7	5,632	19.6	22,385	21.0
2009	24,166	17.8	3,950	13.7	20,216	18.9
2010	14,799	10.9	2,021	7.0	12,778	12.0
Age
Mean (SD)	66.99 (12.66)		72.17 (12.70)		65.60 (12.28)
Median (min–max)	65 (45–111)		74 (45–111)		63 (45–104)
Sex
Male	70,274	51.9	14,967	52.1	55,307	51.8
Region
North East	14,540	10.7	2,894	10.1	11,646	10.9
North Central	48,361	35.7	11,382	39.6	36,979	34.7
South	50,022	36.9	9,962	34.7	40,060	37.5
West	22,188	16.4	4,449	15.5	17,739	16.6
Missing	334	0.2	63	0.2	271	0.3
Insurance type
Fee for service	120,319	88.8	26,321	91.6	93,998	88.1
Non fee or service	15,126	11.2	2,429	8.4	12,697	11.9
Drug use
Short-acting β2-agonists	8,107	6.0	1,981	6.9	6,126	5.7
Long-acting β2-agonists	401	0.3	108	0.4	293	0.3
Short-acting anticholinergics	1,420	1.0	461	1.6	959	0.9
Long-acting anticholinergics	2,717	2.0	542	1.9	2,175	2.0
Methylxanthines	3,332	2.5	923	3.2	2,409	2.3
Systemic glucocorticoids	396	0.3	106	0.4	290	0.3
Mast-cell stabilizers	35	0.0	7	0.0	28	0.0
Leukotriene modifiers	2,159	1.6	467	1.6	1,692	1.6
Antibiotics	65,470	48.3	14,948	52.0	50,522	47.4
Charlson comorbidity score
Mean (STD)	1.02 (1.62)		1.40 (1.85)		0.92 (1.53)
Median (min–max)	0 (0–21)		1 (0–18)		0 (0–21)
Comorbidity
Diabetes	27,691	20.4	7,186	25.0	20,505	19.2
Pulmonary circulation disorders	2,550	1.9	679	2.4	1871	1.8
Hypertension	56,729	41.9	13,035	45.3	43,694	41.0
Chronic pulmonary disease	192	0.1	40	0.1	152	0.1
Alcohol abuse	1,198	0.9	291	1.0	907	0.9
Drug abuse	567	0.4	152	0.5	415	0.4
Congestive heart failure	12,820	9.5	4,543	15.8	8,277	7.8
Valvular disease	12,055	8.9	3,364	11.7	8,691	8.1
Peripheral vascular disease	13,515	10.0	3,969	13.8	9,546	8.9
Chronic peptic ulcer	147	0.1	43	0.1	104	0.1
Liver disease	2,056	1.5	455	1.6	1,601	1.5
Health care resource utilization
All-cause hospitalization	28,221	20.8	8,714	30.3	19,507	18.3
All-cause ED visit	41,584	30.7	11,669	40.6	29,915	28.0

Notes:

^aBaseline = 12 months prior to date of first diagnosis of COPD

^ball variables were statistically different between patients with and without pneumonia at P < 0.001. Chi-square test for categorical variables and – test for continuous variables

^cfor pneumonia onset patients, follow up is from the date of COPD diagnosis to date of onset of pneumonia. For nonpneumonia onset patients, follow up is from the date of COPD diagnosis to end of enrollment or December 31, 2010.

Abbreviations: COPD, chronic obstructive pulmonary disease; ED, emergency department; SD, standard deviation; STD, sexually transmitted disease.