Costs and health care resource utilization among chronic obstructive pulmonary disease patients with newly acquired pneumonia

Figures & data

Figure 1 Patient selection flowchart.

Notes: ^aIdentification determined by COPD-related admissions or emergency room visits or two or more COPD-related office visits on different dates; ^bindex date for newly acquired pneumonia was after COPD diagnosis, and was determined to be the date of any bronchitis claim within 30 days of the first pneumonia diagnosis or of the first pneumonia claim if no bronchitis claims; ^crandomly assigned physician visit date as index date during the study enrollment period and patients with index date before COPD diagnosis were excluded; ^dtwelve-month baseline and 12 months of follow-up.
Abbreviations: COPD, chronic obstructive pulmonary disease; PSM, propensity score matching.

Table 1 Baseline characteristics before and after PSM

	Before PSM (N=467,578)			After PSM
	Pneumonia cohort (n=84,130)	Control cohort (n=383,448)	Absolute standardized differencea	Pneumonia cohort (n=84,130)	Control cohort (n=84,130)	Absolute standardized differencea
Age (years), mean (SD)	70.1 (12.5)	62.7 (12.3)	0.592	70.1 (12.5)	70.2 (12.3)	−0.011
Sex, n (%)			0.061			0.007
Female	41,040 (48.8)	198,786 (51.8)		41,040 (48.8)	41,353 (49.2)
Male	43,090 (51.2)	184,662 (48.2)		43,090 (51.2)	42,777 (50.9)
Health insurance, n (%)
Non-FFSb	8,680 (10.3)	49,629 (12.9)	−0.082	8,680 (10.3)	8,353 (9.9)	0.013
FFS	73,469 (87.3)	324,268 (84.6)	0.080	73,469 (87.3)	73,968 (87.9)	−0.018
Missing	1,981 (2.4)	9,551 (2.5)	−0.009	1,981 (2.4)	1,809 (2.2)	0.014
Regions in the USA, n (%)
Northeast	10,041 (11.9)	52,842 (13.8)	−0.055	10,041 (11.9)	9,862 (11.7)	0.007
North Central	32,365 (38.5)	122,032 (31.8)	0.140	32,365 (38.5)	31,937 (38.0)	0.010
South	29,112 (34.6)	144,937 (37.8)	−0.067	29,112 (34.6)	30,219 (35.9)	−0.028
West	11,267 (13.4)	55,235 (14.4)	−0.029	11,267 (13.4)	10,716 (12.7)	0.019
Unknown	1,345 (1.6)	8,402 (2.2)	-0.043	1,345 (1.6)	1,396 (1.7)	−0.005
CCI score, mean (SD)	3.3 (2.6)	2.6 (2.0)	0.279	3.3 (2.6)	3.2 (2.3)	0.008
Employment status, n (%)
Employed	9,438 (11.2)	80,092 (20.9)	−0.266	9,438 (11.2)	8,712 (10.4)	0.028
Retired	46,348 (55.1)	141,592 (36.9)	0.371	46,348 (55.1)	45,737 (54.4)	0.015
Other	28,344 (33.7)	161,764 (42.2)	−0.176	28,344 (33.7)	29,681 (35.3)	−0.033
Summer (May-October), n (%)	33,080 (39.3)	193,842 (50.6)	−0.227	33,080 (39.3)	32,451 (38.6)	0.015
Medication use, n (%)
Antibiotics	34,892 (41.5)	113,901 (29.7)	0.248	34,892 (41.5)	32,171 (38.2)	0.066
ICS	3,524 (4.2)	8,201 (2.1)	0.117	3,524 (4.2)	3,004 (3.6)	0.032
ICS/LABA	10,153 (12.1)	24,108 (6.3)	0.201	10,153 (12.1)	8,844 (10.5)	0.049
LABA	1,356 (1.6)	2,837 (0.7)	0.081	1,356 (1.6)	1,157 (1.4)	0.020
LTRA	3,450 (4.1)	8,888 (2.3)	0.101	3,450 (4.1)	2,953 (3.5)	0.031
Long-acting anticholinergics	6,941 (8.3)	17,834 (4.7)	0.147	6,941 (8.3)	6,021 (7.2)	0.041
Mast cell stabilizer	30 (0.04)	52 (0.01)	0.014	30 (0.04)	17 (0.02)	0.009
OCS	14,358 (17.1)	38,628 (10.1)	0.205	14,358 (17.1)	12,491 (14.9)	0.061
SABA	8,594 (10.2)	26,403 (6.9)	0.119	8,594 (10.2)	7,113 (8.5)	0.061
Short-acting anticholinergics with/without short-acting β2-agonists	9,791 (11.6)	19,243 (5.0)	0.241	9,791 (11.6)	8,458 (10.1)	0.051
Xanthines	1,675 (2.0)	2,900 (0.8)	0.106	1,675 (2.0)	1,444 (1.7)	0.020
Index date (year), n (%)			−0.357			−0.005
2005	13,431 (16.0)	36,040 (9.4)		13,431 (16.0)	14,525 (17.3)
2006	12,612 (15.0)	36,506 (9.5)		12,612 (15.0)	11,877 (14.1)
2007	13,591 (16.2)	51,440 (13.4)		13,591 (16.2)	13,157 (15.6)
2008	13,917 (16.5)	64,370 (16.8)		13,917 (16.5)	13,121 (15.6)
2009	18,570 (22.1)	98,867 (25.8)		18,570 (22.1)	18,292 (21.7)
2010	12,009 (14.3)	96,225 (25.1)		12,009 (14.3)	13,158 (15.6)
Hospitalizations, n (%)	32,723 (38.9)	94,599 (24.7)	0.309	32,723 (38.9)	33,082 (39.3)	−0.009
Outpatient visits, n (%)
0	6,046 (7.2)	16,536 (4.3)	0.124	6,046 (7.2)	6,030 (7.2)	0.001
≤5	24,318 (28.9)	137,291 (35.8)	0.148	24,318 (28.9)	24,366 (29.0)	−0.001
>5	53,766 (63.9)	229,621 (59.9)	0.083	53,766 (63.9)	53,734 (63.9)	0.001
ER visits, n (%)	38,989 (46.3)	131,041 (34.2)	0.250	38,989 (46.3)	39,407 (46.8)	−0.010

Notes:

a A standardized difference that is less than absolute value 0.1 has been taken to indicate a negligible difference in the mean or prevalence of a covariate between treatment and control groups;

b non-FFS health plan included health maintenance organizations and point of service with capitation; all others coded as FFS.

Abbreviations: PSM, propensity score matching; SD, standard deviation; FFS, fee for service; CCI, Charlson Comorbidity Index; ICS, inhaled corticosteroids; LABA, long-acting β-agonists; LTRA, leukotriene receptor antagonists; OCS, oral corticosteroids; SABA, short-acting β₂-adrenergic receptor agonists; ER, emergency room.

Table 2 Adjusted health care resource utilization and costs for patients with and without pneumonia in follow-up period in the matched population

Variable	Pneumonia cohort	Control cohort	Odds ratio (95% CI)	P-value
Patients, n	84,130	84,130
Resource utilization, n (%)a
All-cause hospitalizations	59,678 (70.9)	18,419 (21.9)	9.2 (8.9, 9.4)	<0.0001
All-cause ER visits	57,252 (68.1)	27,507 (32.7)	4.4 (4.3, 4.5)	<0.001
All-cause outpatient visits	83,948 (99.8)	80,505 (95.7)	1.1 (0.9, 1.3)	0.5
Pneumonia-specific hospitalization	27,882 (33.1)	Not applicable
Pneumonia-specific ER visits	28,982 (34.4)	Not applicable
Pneumonia-specific outpatient visits	62,101 (73.8)	Not applicable
Mean health care cost, US$ (SD)			Cost difference (95% CI)
All-cause hospitalization	$18,209 ($8,325)	$3,856 ($2,035)	$14,353 ($14,037, $14,690)
All-cause outpatient	$14,514 ($7,776)	$7,623 ($3,935)	$6,891 ($6,706, $7,070)
All-cause prescription	$4,103 ($1,339)	$2,998 ($948)	$1,104 ($1,054, $1,142)

Note:

a n denotes the number of patients with health care resource utilization.

Abbreviations: ER, emergency room; SD, standard deviation; CI, confidence interval.