Budget impact model of tobramycin inhalation solution for treatment of Pseudomonas aeruginosa in cystic fibrosis patients

Figures & data

Table 1.  Baseline characteristics, secondary outcomes, and derived annual probabilities (From Ramsey et al. 199914).

	Nebulized tobramycin and standard care	Standard care alone
Baseline characteristics
N	258	262
Males n (%)	149 (58)	132 (50)
Age (years) mean	21	21
6–12 n (%)	55 (21)	61 (23)
13–17 n (%)	63 (24)	67 (26)
≥18 n (%)	140 (54)	134 (51)
Mean FEV1 (±SD) % of  predicted value	49.9 ± 15.5	51.2 ± 16.8
Mean PA density (±SD)  log 10 CFU/g	7.6 ± 1.2	7.3 ± 1.6
Secondary outcomes
Hospitalizations	95	117
Use of IV anti-PA Tx†	100	135
Derived annual probabilities
Hospitalizations	63%	72%
Use of IV anti-PA Tx†	65%	79%

Based on pooled results from the pivotal nebulized tobramycin clinical trial (Ramsey et al. 1999)14.

†Intravenous anti-Pseudomonas aeruginosa (PA) antibiotic treatments.

Table 2.  Model inputs and sources for use of tobramycin inhaled solution in cystic fibrosis.

Inputs	Base-case	Source
Health plan population
Total health plan population	5,000,000	Assumption
Proportion of health plan population age ≥6 years		US 2006 census15
6–18+ years	4,550,000 (91%)	US census15
Prevalence of CF	8.54 per 100,000	Cystic Fibrosis Foundation, 20066
Prevalence of PA infection	56.1%	Razvi et al. 200916
Suppressive treatment for chronic PA infection
TIS nebulized tobramycin inhalation solution  (56 5 ml vials; 300 mg/5 ml; unit WAC)	$3,432 per month	Redbook 200818
Administration	2/day/28 days	Novartis 200719
Number of months on TIS per year	6.5	Assumption
Aerosol mask	$2.00 each 12/year	HCPCS code A701534
Nebulizer (Pari LC Plus)	$14.90 each 2/year	HCPCS code A700534
Air compressor (DeVilbiss Pulmo-Aide)	$89.90	HCPCS code E057034
Air filter (for compressor)	$15.00 each 2/year	HCPCS code A701334
Total annual drug and DME costs for TIS therapy – estimated	$22,481	Calculated
Acute treatment for acute pulmonary exacerbations
Ceftazidime (intravenous, 2 g/8 h, 2 g vial); unit WAC); 14 vials/treatment22	$26.10/vial	Redbook 200818
Tobramycin (intravenous, 3 mg/kg/8 h, 8 ml vial; unit WAC); 28 units/tx course	$10.25/vial	Redbook 200818
Average weight of CF patient	53 kg	Assumption
Duration of treatment (days); days of home infusion	14	Driscoll et al. 200717
Cost of laboratory diagnostics (tobramycin assay)/1/treatment	$133.00	CPT Code 8020018
Average per diem rate for home infusion services (for administration of  intravenous anti-pseudomonal antibiotics treatments)	$105.39	Tice et al. 200225
Total cost of acute treatment for acute pulmonary exacerbations – estimated	$2,261	Calculated
Hospitalization costs
Average cost of hospitalization per CF patient	$10,216	Lieu 199910

CF, cystic fibrosis; PA, Pseudomonas aeruginosa; TIS, tobramycin inhalation solution; DME, durable medical equipment; WAC, wholesale acquisition cost.

Table 3.  Budget impact results of increasing use of tobramycin inhaled solution in cystic fibrosis patients.

	Current utilization	Year 1	Year 2	Year 3	Year 4
Estimated TIS utilization*	20%	25%	30%	35%	40%
Number of patient treated with TIS	44	54	65	76	87
Detailed budget impact results†
Total drug cost	$1,088,216	$1,332,136	$1,576,055	$1,819,975	$2,063,894
Total medical care costs	$1,834,886	$1,822,217	$1,809,548	$1,796,879	$1,784,211
Total hospitalizations	153	152	151	150	149
Total IV anti-PA treatments	167	165	164	162	161
Drug budget
Total	$1,088,216	$1,332,136	$1,576,055	$1,819,975	$2,063,894
PMPM	$0.018	$0.022	$0.026	$0.030	$0.034
PTMPM	$416	$510	$603	$696	$789
PMPY	$0.22	$0.27	$0.32	$0.36	$0.41
PTMPY	$4,995	$6,114	$7,234	$8,353	$9,473
Budget impact relative to budget of current year	n/a	$243,919	$487,839	$731,758	$975,678
% Change relative to budget of current year	n/a	22.4%	45%	67%	90%
Overall budget
Total	$2,923,103	$3,154,353	$3,385,604	$3,616,854	$3,848,105
PMPM	$0.049	$0.053	$0.056	$0.060	$0.064
PTMPM	$1,118	$1,207	$1,295	$1,383	$1,472
PMPY	$0.58	$0.63	$0.68	$0.72	$0.77
PTMPY	$13,417	$14,478	$15,539	$16,601	$17,662
Budget impact relative to budget of current year	n/a	$231,251	$462,501	$693,752	$925,002
% Change relative to budget of current year	n/a	8%	16%	24%	32%

*Assumes that 20% of CF patients are already being treated with TIS; each subsequent year adds 5% more patients having TIS treatment.

†All costs are reported in 2008 US dollars.

PA, Pseudomonas aeruginosa; PMPM, per member per month; PMPY, per member per year; PTMPM, per treated member per month; PTMPY, per treated member per year; TIS, tobramycin inhalation solution.

Figure 1.  One-way sensitivity analysis of incremental budget impact of tobramycin inhaled solution comparing current formulary to year 1 for health plan of 5,000,000 members. *TIS, tobramycin inhaled solution; †IV anti-PA, IV anti-pseudomonal.

Figure 2.  Scenario analyses for a managed-care organization population of 5 million: PMPM costs after 5% increase in use of tobramycin inhaled solution. PMPM, per member per month.

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