Adherence to tobramycin inhaled powder vs inhaled solution in patients with cystic fibrosis: analysis of US insurance claims data

Figures & data

Figure 1 CONSORT diagram showing patient selection for primary and secondary objectives.

Notes: ^aCystic Fibrosis ICD-9-CM: 277.0x, ICD-10-CM: E84.x. ^bEnrollment gap allowance of 45 days applied.
Abbreviations: CONSORT, Consolidated Standards of Reporting Trials; TIP, tobramycin inhalation powder; TIS, tobramycin inhalation solution.

Table 1 Summary of patient demographic characteristics

Baseline characteristics and covariates	Tobramycin inhalation powder cohort (N=145)	Tobramycin inhalation solution cohort (N=306)
Age, mean (SD)	25.0 (11.1)	21.9 (16.2)
Age group, years n (%)
<6	0 (0.0)	33 (10.8)
≥6 and <12	2 (1.4)	49 (16.0)
≥12 and <18	39 (26.9)	65 (21.2)
≥18 and <25	49 (33.8)	70 (22.9)
≥25 and <35	33 (22.8)	36 (11.8)
≥35	22 (15.2)	53 (17.3)
Gender, n (%)
Male	80 (55.2)	154 (50.3)
Female	65 (44.8)	152 (49.7)
Employment status, n (%)
Active full time	105 (72.4)	194 (63.4)
Other/unknown	40 (27.6)	112 (36.6)
Health care plan type, n (%)
Basic/major medical	0 (0.0)	0 (0.0)
Comprehensive	2 (1.4)	7 (2.3)
Exclusive provider organization	1 (0.7)	7 (2.3)
Health maintenance organization	18 (12.4)	57 (18.6)
POS	16 (11.0)	22 (7.2)
Preferred provider organization	77 (53.1)	177 (57.8)
POS with capitation	1 (0.7)	5 (1.6)
Consumer-driven health plan	17 (11.7)	17 (5.6)
High-deductible health plan	11 (7.6)	8 (2.6)
Missing	2 (1.4)	6 (2.0)
Geographic location (US), n (%)
Northeast	30 (20.7)	43 (14.1)
North central	39 (26.9)	76 (24.8)
South	52 (35.9)	112 (36.6)
West	23 (15.9)	73 (23.9)
Unknown	1 (0.7)	2 (0.7)
Co-payment (of index treatment), mean US$ (SD)	60.3 (83.8)	49.0 (96.1)

Abbreviations: POS, point of service; SD, standard deviation.

Table 2 Summary of patient clinical characteristics

Pre-index comorbidities	Tobramycin inhalation powder cohort (N=145)	Tobramycin inhalation solution cohort (N=306)
CCI, mean (standard deviation)	2.44 (1.92)	2.35 (2.07)
Single items of CCI, n (%)
Myocardial infarction	0 (0.0)	3 (1.0)
Congestive heart failure	14 (9.7)	26 (8.5)
Peripheral vascular disease	1 (0.7)	8 (2.6)
Cerebrovascular disease	14 (9.7)	37 (12.1)
Dementia	0 (0.0)	0 (0.0)
Chronic pulmonary disease	121 (83.5)	245 (80.1)
Rheumatic disease	86 (59.3)	176 (57.5)
Peptic ulcer disease	3 (2.1)	3 (1.0)
Mild liver disease	13 (9.0)	31 (10.1)
Diabetes without chronic complication	49 (33.8)	64 (20.9)
Diabetes with chronic complication	9 (6.2)	10 (3.3)
Hemiplegia or paraplegia	1 (0.7)	8 (2.6)
Renal disease	5 (3.5)	14 (4.6)
Any malignancy	4 (2.8)	14 (4.6)
Moderate or severe liver disease	3 (2.1)	5 (1.6)
Metastatic solid tumor	0 (0.0)	3 (1.0)
Acquired immune deficiency syndrome/human immunodeficiency virus	1 (0.7)	0 (0.0)
Selected comorbidities, n (%)
Pancreatic insufficiency	136 (93.8)	266 (86.9)
Gastroesophageal reflux	48 (33.1)	103 (33.7)
Chronic sinusitis	93 (64.1)	160 (52.3)
Malnutrition	44 (30.3)	58 (19.0)
Osteoporosis	21 (14.5)	32 (10.5)
Liver and lung transplant and aftercare	8 (5.5)	9 (2.9)
Depression	33 (22.8)	38 (12.4)
Anxiety	6 (4.1)	5 (1.6)

Abbreviation: CCI, Charlson Comorbidity Index.

Table 3 Multivariable analysis of adherence to tobramycin inhalation powder relative to tobramycin inhalation solution (high vs low/medium utilization)

Variables included in the model	Odds ratio estimate (95% confidence interval)
Index drug, gender, age, Charlson Comorbidity	1.521 (0.992–2.333)
A priori variables + employment status	1.530 (0.996–2.351)
A priori variables + health plan type	1.448 (0.933–2.248)
A priori variables + geographic location	1.566 (1.016–2.413)
A priori variables + co-payment	1.517 (0.989–2.326)
A priori variables + comorbidities
Pancreatic insufficiency	1.555 (1.012–2.390)
Gastroesophageal reflux	1.549 (1.007–2.383)
Chronic sinusitis	1.449 (0.976–2.301)
Malnutrition	1.530 (0.996–2.350)
Osteoporosis	1.519 (0.990–2.330)
Liver and lung transplant and aftercare	1.535 (1.000–2.356)
Anxiety	1.540 (1.003–2.365)