Long-term persistency and costs associated with the use of iron chelation therapies in the treatment of Sickle cell disease within Medicaid programs

Figures & data

Table 1.  Baseline descriptive characteristics.

Characteristic	Deferoxamine use† (n = 166)	Deferasirox use† (n = 238)	p-value	Overall (n = 404)
Age in years, M (SD)	17.7 (±9.4)	19.4 (±12.0)	0.131	18.7 (±11.0)
Age ≥ 18 years, n (%)	69 (41.6%)	112 (47.1%)	0.275	181 (44.8%)
Gender, male, n, (%)	87‡ (52.4%)	98‡ (41.2%)	0.026	185 (45.8%)
Deyo-Charlson, M (SD)	0.87 (±1.05)	0.74 (±1.16)	0.258	0.79 (±1.12)
Race
Black, n (%)	115 (69.3%)	154 (64.7%)	0.338	269 (66.7%)
Hispanic, n (%)	1 (0.6%)	2 (0.8%)	0.784	3 (0.7%)
White, n (%)	1 (0.6%)	5 (2.1%)	0.221	6 (1.5%)
Other, n (%)	49 (29.5%)	77 (32.4%)	0.545	126 (31.2%)
Capitated Medicaid coverage, n (%)	96 (57.8%)	156 (65.5%)	0.115	252 (62.4%)
Number of baseline period transfusions, M (SD)	3.7‡ (±3.2)	2.7‡ (±3.3)	0.003	3.1 (±3.3)
Comorbidities
Coronary Heart Disease	14 (8.4%)	5 (2.1%)	0.497	7 (1.7%)
Chronic Liver Disease	6 (3.6%)	4 (1.7%)	0.218	10 (2.5%)
Chronic Renal Disease	3 (1.8%)	7 (2.9%)	0.470	10 (2.5%)
Coronary Occlusion with Infarction	2 (1.2%)	10 (4.2%)	0.077	24 (5.9%)
Diabetes	3 (1.8%)	2 (0.8%)	0.387	5 (1.2%)
Hypertension	10 (6.0%)	18 (7.6%)	0.549	28 (6.9%)
Other Cerebrovascular Disease	22 (13.3%)	28 (11.8%)	0.655	50 (12.4%)

†Defined as the drug begun at the index date.

‡Significantly different between groups (independent groups t-test, Wilcoxon Signed Rank test, or χ2, p ≤ 0.05).

Figure 1.  Kaplan-Meier graph for treatment persistency between Deferoxamine use and Deferasirox use. †Defined as the drug begun at the index date. Time at risk = 86,336; Log rank test for equality of survivor functions p = 0.004.

Table 2.  Predictors of treatment discontinuation.

Variable	Hazard ratio	Standard error	Test statistic	p-value	95% CI, lower bound	95% CI, upper bound
Deferoxamine use (vs Deferasirox)†	1.305‡	0.139	2.50	0.012	1.059	1.607
Number of pre-index transfusion episodes	0.982	0.017	−1.08	0.281	0.951	1.015
18 years of age or older	1.304‡	0.138	2.50	0.013	1.059	1.605
Male	1.049	0.108	0.45	0.641	0.857	1.285
Capitated Medicaid coverage	1.118	0.117	1.06	0.287	0.911	1.372
Deyo-Charlson	0.988	0.042	−0.29	0.772	0.908	1.074

Cox Proportional Hazard Regression, Efron method for ties; n = 404; time at risk 86,336; Log-likelihood − 2015.97; p = 0.009.

†Defined as the drug begun at the index date.

‡Statistically significant at p ≤ 0.05.

Table 3.  Baseline and study period per member per month (PMPM) unadjusted average costs according to treatment groups.

Characteristic	Deferoxamine use† (n = 166)	Deferasirox use† (n = 228)	p-value	Overall (n = 404)
Inpatient PMPM Costs [mean (±SD)]
Baseline	$2600 (±5938)	$3679 (±7958)	0.271	$3236 (±7209)
Study	$2742 (±5752)	$4062 (±9357)	0.364	$3519 (±8091)
Outpatient PMPM Costs [mean (±SD)]
Baseline	$1643 (±1482)	$925 (±1317)	<0.001	$1220 (±1430)
Study	$1374 (±1132)‡	$904 (±1270)‡	<0.001	$1098 (±1236)
Medication PMPM Costs [mean (±SD)]
Baseline	$933 (±808)‡	$252 (±675)‡	<0.001	$532 (±805)
Study	$1614 (±1266)‡	$2124 (±1488)‡	<0.001	$1915 (±1422)
Total PMPM Costs [mean (±SD)]
Baseline	$5176 (±6219)‡	$4856 (±8428)‡	<0.001	$4988 (±7592)
Study	$5730 (±6340)	$7090 (±9812)	0.304	$6532 (±8575)

†Defined as the drug begun at the index date.

‡Significantly different between groups (Mann-Whitney U, p ≤ 0.05).

Table 4.  Predictors of total healthcare costs.

Variable	exp(b)	Standard error	Z	p-value	95% CI, lower bound	95% CI, upper bound
Deferoxamine use (vs Deferasirox)†	0.924	0.077	−0.95	0.340	0.784	1.087
Number of pre-index transfusion episodes	1.028‡	0.012	2.31	0.021	1.001	1.053
18 years of age or older	1.559‡	0.140	4.96	<0.001	1.308	1.859
Male	0.948	0.080	−0.63	0.526	0.804	1.118
Capitated Medicaid coverage	0.989	0.082	−0.14	0.892	0.841	1.162
Deyo Charlson	1.100‡	0.042	2.51	0.012	1.021	1.185
Baseline healthcare costs (per thousand dollars)	1.011‡	0.001	9.68	<0.001	1.001	1.014

Generalized Linear Model, gamma distribution family, log link; Maximum likelihood estimation, n = 404; Observed Information Matrix (OIM) Log-likelihood = −5031.28; Deviance = 202.06; Akaike information criteria, AIC = 24.95.

†Defined as the drug begun at the index date.

‡Statistically significant at p ≤ 0.05.

Roseff SD. Sickle cell disease: a review. Immunohematology 2009;25:67–74

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