Adherence to dornase alfa treatment among commercially insured patients with cystic fibrosis

Figures & data

Figure 1. Study timeline for patients with cystic fibrosis who were treated with dornase alfa; 54 × 23 mm (300 × 300 DPI).

Table 1. Demographics and selected baseline characteristics of cystic fibrosis patients treated with dornase alfa.

Variable	All (n = 907)
New dornase alfa user (no fills in 12 mo), n (%)	238 (26.2)
Age, mean (SD), years	19.5 (11.5)
Age group, no. (%), years
5–12	274 (30.2)
13–20	337 (37.2)
21–30	140 (15.4)
31+	156 (17.2)
Female, n (%)	445 (49.1)
Usual-care physician specialty, n (%)
Pulmonologist	327 (36.1)
Primary care	266 (29.3)
Gastroenterology	27 (3.0)
Otolaryngology	23 (2.5)
Other^a	133 (14.7)
Unknown^b	131 (14.4)
Annual pulmonologist visits, mean (SD) [median]	5.3 (9.2) [3]
Charlson comorbidity index, mean (SD) [median]	1.2 (1.5) [1]
No. of chronic conditions^c, mean (SD) [median]	2.3 (1.3) [2]
Comorbidities associated with CF^d, n (%)
Diabetes	154 (17.0)
Pancreatic insufficiency	734 (80.9)
Pseudomonas infection	705 (77.7)
Gastroesophageal reflux	65 (7.2)
Chronic sinusitis	215 (23.7)
Malnutrition or failure to thrive	65 (7.2)
Osteoporosis	16 (1.8)
Allergic bronchopulmonary aspergillosis	16 (1.8)
Any use of inhaled antibiotics, n (%)	527 (58.1)
No. of fills of oral or IV antibiotics, mean (SD) [median]	3.8 (3.6) [3]
Any use of inhaled steroids (including steroid combination), n (%)	486 (53.6)
Any use of hypertonic saline, n (%)	187 (20.6)

^aIndividual specialties making up less than 2% of the total.

^bNo data on specialty or no qualifying visits.

^cA condition expected to last ≥12 months and resulting in functional limitations and/or the need for ongoing medical care. Identified using a validated list of ICD-9-CM codes6.

^dDerived from literature and identified using a published list of ICD-9-CM codes7.

CF, cystic fibrosis; ICD-9-CM, International Classification of Diseases, 9th Revision, Clinical Modification; IV, intravenous; SD, standard deviation.

Table 2. Dornase alfa adherence as measured by medication possession ratio in the post-index period.

	No. of patients	Mean	(SD)	[Median]	p-value^a
All	907	0.59	(0.30)	[0.60]
New or continuing user^b					<0.001
New	238	0.39	(0.26)	[0.32]
Continuing	669	0.66	(0.28)	[0.70]
Patient age, years					<0.001
5–12	274	0.66	(0.29)	[0.71]
13–20	337	0.57	(0.29)	[0.55]
21–30	140	0.54	(0.30)	[0.52]
31+	156	0.56	(0.31)	[0.58]
Gender					0.883
Male	462	0.59	(0.30)	[0.59]
Female	445	0.59	(0.30)	[0.61]
Region					0.285
North Central	269	0.60	(0.30)	[0.65]
Northeast	113	0.55	(0.31)	[0.58]
South	383	0.58	(0.30)	[0.57]
West	142	0.62	(0.28)	[0.61]
Season^c					<0.001
Spring	907	0.59	(0.36)	[0.65]
Summer	907	0.56	(0.37)	[0.65]
Fall	907	0.61	(0.35)	[0.68]
Winter	907	0.61	(0.34)	[0.67]

^aF-test was used for comparisons between new and continuing users, across age groups, between genders, and across regions. Repeated measure analysis was used for comparison across seasons.

^bNew users had no fills of dornase alfa for ≥12 months, continuing users had at least one fill.

^cMedication possession ratio for season calculated using the 3 months of that season alone rather than the entire post-index period.

SD, standard deviation.

Table 3. Utilization and healthcare charges in the outcome period, stratified by dornase alfa adherence, in patients with cystic fibrosis.

Variable	All (n = 907)	MPR			p-value
		<0.5 (n = 380; 41.9%)	0.5–<0.8 (n = 229; 25.2%)	0.8–1.0 (n = 298; 32.9%)
Any inpatient respiratory exacerbation, n (%)	201 (22.2)	93 (24.5)	51 (22.3)	57 (19.1)	0.250
LOS^a, mean (SD) [median]	14.3 (16.2)9	17.3 (19.1)11	12.6 (15.2)8	10.8 (10.0)7	0.038
Any ED visit for respiratory exacerbation, n (%)	37 (4.1)	19 (5.0)	6 (2.6)	12 (4.0)	0.355
No. of outpatient visits for respiratory exacerbations, mean (SD)	1.2 (3.1)	1.3 (3.7)	1.3 (2.9)	1.2 (2.4)	0.880
No. of fills of oral or IV antibiotics, mean (SD) [median]	4.4 (4.1)3	3.9 (3.6)3	4.4 (4.2)3	5.1 (4.6)4	<0.001
Total healthcare charges, $ mean (SD) [median]	64,426 (71,019) [44,878]	58,612 (81,959) [32,765]	67,565 (68,380) [44,492]	69,427 (56,110) [55,524]	0.107
Total respiratory exacerbation–related charges^b, $ mean (SD) [median]	13,620 (41,484) [426]	17,163 (48,469) [374]	13,408 (41,265) [399]	9264 (30,159) [472]	0.048

^aAmong 201 patients with at least one respiratory exacerbation requiring inpatient care.

^bRespiratory exacerbation related were charges identified for (1) medical claims for hemoptysis, pneumothorax, acute asthma, acute respiratory infection, pneumonia, influenza, acute respiratory failure, or bronchospasm; and (2) pharmacy claim for oral or IV antibiotics (except oral azithromycin).

LOS, hospital length of stay; ED, emergency department, MPR, medication possession ratio; SD, standard deviation.

Figure 2. Forest plots of multivariate model results for patients with cystic fibrosis who were treated with dornase alfa. (A) Cox regression: risk of inpatient respiratory exacerbation. (B) Generalized linear model: all cause healthcare costs.

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