Retrospective observational study of asthma and chronic obstructive pulmonary disease prevalence and associated healthcare resource utilization in a large, integrated healthcare system

Figures & data

Table 1. Patient demographics and baseline characteristics

Variable	Overall study population (N = 149,086)			Patients with ≥1 outpatient visit (N = 47,805)
	Asthma (n = 90,569)	COPD (n = 48,302)	Asthma + COPD (n = 10,215)	Asthma (n = 31,494)	COPD (n = 12,301)	Asthma + COPD (n = 4010)
Disease period prevalence^a (%)	5.20	2.77	0.59	1.81	0.07	0.02
Age, mean (SD) (years)	37.59 (21.7)	69.60 (11.6)	66.78 (12.6)	37.53 (23.2)	70.22 (10.9)	67.46 (12.0)
Age category, n (%)
0–17	19,948 (22.0%)	0	0	9476 (30.1%)	0	0
18–29	18,812 (20.8%)	0	0	4024 (12.8%)	0	0
30–39	13,374 (14.8%)	0	0	3592 (11.4%)	0	0
40–49	10,602 (11.7%)	2085 (4.3%)	922 (9.0%)	3595 (11.4%)	393 (3.2%)	303 (7.6%)
50–59	10,225 (11.3%)	8023 (16.6%)	2266 (22.2%)	3891 (12.4%)	1816 (14.8%)	834 (20.8%)
60–69	8874 (9.8%)	13,438 (27.8%)	2725 (26.7%)	3660 (11.6%)	3379 (27.5%)	1054 (26.3%)
70–79	5816 (6.4%)	14,593 (30.2%)	2486 (24.3%)	2297 (7.3%)	4120 (33.5%)	1119 (27.9%)
≥80	2918 (3.2%)	10,163 (21.0%)	1816 (17.8%)	959 (3.1%)	2593 (21.1%)	700 (17.5%)
Sex
Male	33,025 (36.5%)	24,067 (49.8%)	3348 (32.8%)	12,343 (39.2%)	6096 (49.6%)	1307 (32.6%)
Female	57,544 (63.5%)	24,235 (50.2%)	6867 (67.2%)	19,151 (60.8%)	6205 (50.4%)	2703 (67.4%)
Race
White	57,490 (63.5%)	39,805 (82.4%)	7686 (75.2%)	20,747 (65.9%)	10,624 (86.4%)	3361 (83.8%)
Black	23,813 (26.3%)	6140 (12.7%)	2049 (20.1%)	5546 (17.6%)	914 (7.4%)	467 (11.7%)
Asian	1137 (1.3%)	401 (0.8%)	131 (1.3%)	380 (1.2%)	80 (0.7%)	30 (0.8%)
American Indian	252 (0.3%)	105 (0.2%)	27 (0.3%)	112 (0.4%)	43 (0.4%)	15 (0.4%)
Hawaiian/Pacific	158 (0.2%)	23 (0.1%)	8 (0.1%)	111 (0.4%)	16 (0.1%)	7 (0.2%)
Other	4249 (4.7%)	646 (1.3%)	136 (1.3%)	2639 (8.4%)	302 (2.5%)	90 (2.2%)
Unknown	3470 (3.8%)	1182 (2.5%)	178 (1.7%)	1959 (6.2%)	322 (2.6%)	40 (1.0%)
Ethnicity
Hispanic	14,878 (16.4%)	2307 (4.8%)	647 (6.3%)	4635 (14.7%)	488 (4.0%)	249 (6.2%)
Non-Hispanic	72,235 (79.8%)	44,776 (92.7%)	9381 (91.8%)	24,875 (79.0%)	11,470 (93.2%)	3712 (92.6%)
Unknown	3456 (3.8%)	1219 (2.5%)	187 (1.8%)	1984 (6.3%)	343 (2.8%)	49 (1.2%)
Elixhauser Comorbidity Index score, mean (SD)^b	3.27 (1.9%)	4.31 (1.9%)	4.31 (1.9%)	3.30 (1.9%)	4.24 (1.9%)	4.33 (1.9%)
Insurance type
Commercial	46,650 (51.5%)	10,928 (22.6%)	2540 (24.9%)	17,449 (55.4%)	1687 (13.7%)	701 (17.5%)
Medicaid	12,518 (13.8%)	2847 (5.9%)	808 (7.9%)	5495 (17.5%)	527 (4.3%)	244 (6.1%)
Medicare	14,678 (16.2%)	29,854 (61.8%)	5977 (58.5%)	6121 (19.4%)	9414 (76.5%)	2830 (70.6%)
Other government^c	2803 (3.1%)	1800 (3.7%)	227 (2.2%)	1330 (4.2%)	292 (2.4%)	73 (1.8%)
Self/unknown	13,920 (15.4%)	2873 (6.0%)	663 (6.5%)	1099 (3.5%)	381 (3.1%)	162 (4.0%)
Smoking status
Never	32,014 (35.4%)	2289 (4.7%)	1221 (12.0%)	21,377 (67.9%)	1002 (8.2%)	912 (22.7%)
Former	9075 (10.0%)	11,500 (23.8%)	2677 (26.2%)	5553 (17.6%)	7194 (58.5%)	2136 (53.3%)
Current	5475 (6.1%)	7091 (14.7%)	1310 (12.8%)	2349 (7.5%)	3984 (32.4%)	896 (22.3%)
Passive smoke exposure	2604 (2.9%)	91 (0.2%)	57 (0.6%)	1862 (5.9%)	49 (0.4%)	48 (1.2%)
Unknown	41,401 (45.7%)	27,331 (56.6%)	4950 (48.5%)	353 (1.1%)	72 (0.6%)	18 (0.5%)
Number of BSWH encounters
1	52,707 (58.2%)	24,947 (51.7%)	1627 (15.9%)	12,389 (39.3%)	2338 (19.0%)	77 (1.9%)
2	16,210 (17.9%)	8145 (16.9%)	1689 (16.5%)	6562 (20.8%)	1728 (14.1%)	322 (8.0%)
3–5	15,084 (16.7%)	8531 (17.7%)	3076 (30.1%)	8175 (26.0%)	3422 (27.8%)	1120 (27.9%)
6–10	4863 (5.4%)	4238 (8.8%)	2111 (20.7%)	3215 (10.2%)	2781 (22.6%)	1222 (30.5%)
>10	1705 (1.9%)	2441 (5.1%)	1712 (16.8%)	1153 (3.7%)	2032 (16.5%)	1269 (31.7%)

^a Period prevalence of asthma, COPD, and asthma + COPD calculated as follows: number of unique patients in cohort with diagnosis/number of unique patients with a BSWH visit during the 2016–2018 study period (N = 1,739,282).

^b Calculated based on ICD-10 and DRG codes from baseline hospital admission for patients with a hospitalization.

^c Includes Champus, TRICARE, and Veteran’s Administration.

BSWH indicates Baylor Scott & White Health; COPD, chronic obstructive pulmonary disease; DRG, diagnosis-related group; ICD-10, International Statistical Classification of Diseases and Related Health Problems, 10th Revision; SD, standard deviation.

Table 2. Pharmacotherapy at baseline

Medications^a	Overall study population (N = 149,086)			Patients with ≥1 outpatient visit (N = 47,805)
	Asthma (n = 90,569)	COPD (n = 48,302)	Asthma + COPD (n = 10,215)	Asthma (n = 31,494)	COPD (n = 12,301)	Asthma + COPD (n = 4010)
Maintenance therapies	15,528 (17.1%)	10,046 (20.8%)	3235 (31.7%)	12,062 (38.3%)	6358 (51.7%)	2499 (62.3%)
LABA alone	18 (0.0%)	48 (0.1%)	17 (0.2%)	16 (0.1%)	40 (0.3%)	14 (0.4%)
LAMA alone	46 (0.1%)	939 (1.9%)	141 (1.4%)	37 (0.1%)	759 (6.2%)	111 (2.8%)
ICS alone	5045 (5.6%)	631 (1.3%)	268 (2.6%)	4322 (13.7%)	238 (1.9%)	173 (4.3%)
ICS + LABA^b	5245 (5.8%)	1869 (3.9%)	823 (8.1%)	4611 (14.6%)	1424 (11.6%)	684 (17.1%)
ICS + LAMA^b	4 (0.0%)	73 (0.2%)	14 (0.1%)	3 (0.0%)	37 (0.3%)	6 (0.2%)
LAMA + LABA^b	3284 (3.6%)	3777 (7.8%)	946 (9.3%)	1576 (5.0%)	1929 (15.7%)	653 (16.3%)
ICS + LABA + LAMA^b	1886 (2.1%)	2709 (5.6%)	1026 (10.0%)	1497 (4.8%)	1931 (15.7%)	858 (21.4%)
SAMA, SABA, or SAMA/SABA^b	41,058 (45.3%)	19,306 (40.0%)	5583 (54.7%)	24,539 (77.9%)	7352 (59.8%)	2966 (74.0%)
Methylxanthines	83 (0.1%)	135 (0.3%)	53 (0.5%)	51 (0.2%)	74 (0.6%)	45 (1.1%)
Oral/intravenous corticosteroids	27,535 (30.4%)	13,464 (27.9%)	3960 (38.8%)	12,281 (39.0%)	4431 (36.0%)	1950 (48.6%)
PDE4 inhibitors	2 (0.0%)	63 (0.1%)	23 (0.2%)	2 (0.0%)	55 (0.5%)	21 (0.5%)
Biologics	29 (0.0%)	1 (0.0%)	5 (0.1%)	24 (0.1%)	1 (0.0%)	5 (0.1%)
Leukotrienes	7403 (8.2%)	722 (1.5%)	701 (6.9%)	6437 (20.4%)	492 (4.0%)	552 (13.8%)
Antibiotics	41,490 (45.8%)	27,550 (57.0%)	6513 (63.8%)	21,944 (69.7%)	9207 (74.9%)	3373 (84.1%)
No medication	28,943 (32.0%)	13,783 (28.5%)	2201 (21.6%)	1723 (5.5%)	1230 (10.0%)	189 (4.7%)

^a Includes all medication orders that were active at the time of the index encounter or entered within 7 days following the encounter. The index encounter is defined as the first patient visit to a BSWH inpatient or outpatient facility between January 1, 2016, and December 31, 2018.

^b Any combination.

BSWH indicates Baylor Scott & White Health; COPD, chronic obstructive pulmonary disease; ICS, inhaled corticosteroid; LABA, long-acting beta₂-agonist; LAMA, long-acting muscarinic antagonist; PDE4, phosphodiesterase type 4; SABA, short-acting beta₂-agonist; SAMA, short-acting muscarinic antagonist.

Figure 1. Kaplan-Meier estimates of the probability of no exacerbation in patients with asthma or chronic obstructive pulmonary disease (COPD) only and ≥2 visits. The number of patients at risk is displayed for each time point. Patients with asthma and COPD were not included in the analysis.

Table 3. Summary of exacerbations

Characteristics	Patients with ≥2 BSWH encounters			Patients with ≥1 outpatient visit and ≥2 BSWH encounters
	Asthma (n = 37,860)	COPD (n = 23,353)	Asthma + COPD (n = 8588)	Asthma (n = 19,104)	COPD (n = 9963)	Asthma + COPD (n = 3933)
Patients with exacerbations	12,643 (33.4%)	7824 (33.5%)	4214 (49.1%)	8911 (46.6%)	4991 (50.1%)	2620 (66.6%)
Exacerbations	22,530 (100%)	15,502 (100%)	11,025 (100%)	16,408 (100%)	11,175 (100%)	7538 (100%)
Severe	826 (3.7%)	3312 (21.4%)	2160 (19.6%)	325 (2.0%)	810 (7.3%)	578 (7.7%)
Moderate	21,704 (96.3%)	12,190 (78.6%)	8865 (80.4%)	16,083 (98.0%)	10,365 (92.8%)	6960 (92.3%)
Total observational time (patient-days)^a	12,579,659	7,102,207	3,015,544	6,938,120	3,518,768	1,420,038
Annual rate of exacerbations^b	0.65	0.80	1.33	0.86	1.16	1.94

^a Total observational time = number of days between index admission and last visit to a BSWH facility as of December 31, 2018. Patients with only one BSWH visit during the study timeframe were excluded from the calculation.

^b Annual rate of exacerbations = total number of exacerbations/(total observational time [days])/365.

BSWH indicates Baylor Scott & White Health; COPD, chronic obstructive pulmonary disease.

Table 4. Healthcare resource utilization

Characteristics	Overall study population		Patients with ≥1 outpatient visit
	Asthma (n = 90,569)	COPD (n = 48,302)	Asthma (n = 31,494)	COPD (n = 12,301)
Patients with a PCP visit	28,263 (31.2%)	9489 (19.7%)	28,263 (89.7%)	9489 (77.1%)
Total number of PCP visits (PPPM)^a	60,383 (0.2)	32,356 (0.1)	60,383 (0.3)	32,356 (0.3)
Patients with a pulmonologist/allergist visit	6777 (7.5%)	5987 (12.4%)	6777 (21.5%)	5987 (48.7%)
Total number of pulmonologist/allergist visits (PPPM)^a	17,289 (0.0)	20,537 (0.1)	17,289 (0.1)	20,537 (0.2)
Patients with an ED visit	47,950 (52.9%)	16,975 (35.1%)	5805 (18.4%)	3072 (25.0%)
Total number of ED visits (PPPM)^a	86,747 (0.2)	31,556 (0.1)	12,970 (0.1)	6964 (0.1)
Patients with a hospitalization	24,185 (26.7%)	31,755 (65.7%)	3248 (10.3%)	4503 (36.6%)
Total number of hospitalizations (PPPM)^a	33,478 (0.1)	54,043 (0.2)	5146 (0.0)	9924 (0.1)
Patients with ICU utilization	9007 (9.9%)	20,246 (41.9%)	443 (1.4%)	979 (8.0%)
Patients with mechanical ventilation utilization	1923 (2.1%)	4822 (10.0%)	1011 (3.2%)	2442 (19.9%)
Patients with nebulizer utilization (no inhaler)^b	3203 (3.5%)	3175 (6.6%)	1049 (3.3%)	928 (7.5%)
Patients with inhaler therapy utilization (no nebulizer)^c	24,625 (27.2%)	18,082 (37.4%)	14,960 (47.5%)	2394 (19.5%)
Patients with inhalation and nebulization utilization^d	17,410 (19.2%)	11,430 (23.7%)	12,024 (38.2%)	7258 (59.0%)
Patients with a pneumonia diagnosis	5749 (6.4%)	5880 (12.2%)	3076 (9.8%)	2720 (22.1%)
Inpatient death	427 (0.5%)	2559 (5.3%)	28 (0.1%)	287 (2.3%)
30-day all-cause readmission rate^e	1843 (7.6%)	4600 (14.5%)	254 (7.8%)	908 (20.2%)
30-day diagnosis-related^f readmission rate^e	111 (0.5%)	694 (2.2%)	0 (0.0%)	4 (0.1%)
90-day all-cause readmission rate^g	1936 (8.0%)	4766 (15.0%)	262 (8.1%)	934 (20.7%)
90-day diagnosis-related^f readmission rate^g	124 (0.5%)	761 (2.4%)	0 (0.0%)	5 (0.1%)

^a PPPM rate calculated as (number of visits/[total observational time/365])/12. Total observational time = 12,579,659 days (asthma) and 7,102,207 days (COPD). Total observational time (patients with ≥1 PCP/pulmonologist visit) = 6,938,120 days (asthma) and 3,518,768 days (COPD).

^b Patients who had an order for a nebulizer at any point during the study timeframe.

^c Patients who had an order for an inhaler at any point during the study timeframe.

^d Patients who had an order for an inhaler and an order for a nebulizer at any point during the study timeframe.

^e Number of patients with a 30-day readmission divided by the number of patients with a hospitalization.

^f Diagnosis-related readmission indicated by the presence of an asthma or COPD ICD-10 code in the primary or secondary diagnosis position.

^g Number of patients with a 90-day readmission divided by the number of patients with a hospitalization.

COPD indicates chronic obstructive pulmonary disease; ED, emergency department; ICD-10, International Statistical Classification of Diseases and Related Health Problems, 10th Revision; ICU, intensive care unit; PCP, primary care provider; PPPM, per patient per month.