Comparison of second-generation antipsychotic treatment on psychiatric hospitalization in Medicaid beneficiaries with bipolar disorder

Figures & data

Table 1.  Sample inclusion and exclusion criteria and sample sizes.

	n	%
Inclusion criteria
Initiate second generation antipsychotic between 1/1/2003 and 6/30/2008	1,102,270
One and only one SGA at index (within 30 days)	1,035,766	94.0%
Aged 18–64 at index	623,562	56.6%
180 days continuous enrollment before (designated the ‘baseline period’) index	277,118	25.1%
360 days after (designated the ‘follow-up period’) index	209,568	19.0%
Bipolar disorder diagnosis	50,422	4.6%
Mental Health and Substance Abuse services coverage	45,196	4.1%
Exclusion criteria*
Medicare eligibility	0	0.0%
Use of any SGA during the baseline period	16,026	35.5%
≥90-day supply prescription for a second-generation antipsychotic	45	0.1%
Schizophrenia diagnosis	5447	12.1%
Residence in nursing homes, hospice, or other type of long-term care facilities	287	0.6%
Patients with a psychiatric hospitalization within 7 days following index	349	0.8%
Patients with capitated payments on their claims (Healthcare cost analyses only)	8385	18.6%
Hospitalization analysis patients	22,479	49.7%
Aripiprazole at index†	2553	5.6%
Olanzapine at index	4702	10.4%
Quetiapine at index	9327	20.6%
Risperidone at index	4377	9.7%
Ziprasidone at index	1520	3.4%
Cost analysis patients	14,094	31.2%
Aripiprazole at index‡	1622	11.5%
Olanzapine at index	3058	21.7%
Quetiapine at index	5746	40.8%
Risperidone at index	2705	19.2%
Ziprasidone at index	963	6.8%

*Each criterion is applied in order from the remaining patients not excluded above. The percentages are out of the final number of included patients.

†Percentages for SGAs at index are out of the total number of hospitalization analysis patients.

‡Percentages for SGAs at index are out of the total number of cost analysis patients.

Table 2.  Demographic characteristics of the study sample.

	Aripiprazole (n = 2553)		Olanzapine (n = 4702)		p	Quetiapine (n = 9327)		p	Risperidone (n = 4377)		p	Ziprasidone (n = 1520)		p
Age (mean, SD)	35.3	10.9	36.4	11.1	<0.0001	36.3	10.7	<0.0001	36.1	11.0	0.0032	35.8	10.6	0.14
Female (n, %)	2062	81%	3430	73%		7361	79%		3321	76%		1217	80%
Race (n, %)					0.12			0.20			<0.0001			0.023
Caucasian	2078	81%	3792	81%		7653	82%		3367	77%		1200	79%
African American	291	11%	597	13%		1093	12%		673	15%		226	15%
Hispanic	24	1%	33	1%		53	1%		45	1%		11	1%
Other	52	2%	116	2%		182	2%		106	2%		27	2%
Unknown	108	4%	164	3%		346	4%		186	4%		56	4%
Insurance type (n, %)					0.20			0.075			0.15			0.91
Capitated	931	36%	1644	35%		3581	38%		1672	38%		557	37%
Fee-for-service	1622	64%	3058	65%		5746	62%		2705	62%		963	63%
Index year (n, %)					<0.0001			<0.0001			<0.0001			<0.0001
2003	515	20%	2623	56%		2482	27%		1506	34%		355	23%
2004	612	24%	1258	27%		2520	27%		1336	31%		367	24%
2005	487	19%	400	9%		1838	20%		680	16%		322	21%
2006	339	13%	155	3%		890	10%		365	8%		187	12%
2007	346	14%	179	4%		1025	11%		316	7%		199	13%
2008	254	10%	87	2%		572	6%		174	4%		90	6%

Note: p-value corresponds to aripiprazole vs comparator to left of p-value column.

Table 3.  Clinical characteristics of the study sample.

	Aripiprazole (n = 2553)		Olanzapine (n = 4702)		p	Quetiapine (n = 9327)		p	Risperidone (n = 4377)		p	Ziprasidone (n = 1520)		p
Psychiatric hospitalization (n, %)	376	15%	684	15%	0.84	1735	19%	< 0.0001	749	17%	0.0094	269	18%	0.012
Diabetes (n, %)	258	10%	281	6%	<0.0001	797	9%	0.014	400	9%	0.19	154	10%	0.98
Hyperlipidemia (n, %)	205	8%	258	5%	<0.0001	730	8%	0.74	311	7%	0.16	108	7%	0.28
Lipid screening (n, %)	467	18%	540	11%	<0.0001	1377	15%	<0.0001	588	13%	<0.0001	259	17%	0.31
Glucose screening (n, %)	153	6%	214	5%	0.0075	519	6%	0.41	234	5%	0.26	95	6%	0.74
DCI* (M, SD)	0.4	0.9	0.4	1.0	0.79	0.5	1.0	0.035	0.5	1.1	0.020	0.4	1.0	0.46
Total expenditures (M, SD)	$7788	$12,263	$8237	$25,268	0.41	$8894	$18,667	0.0048	$8697	$16,663	0.040	$7954	$18,710	0.81
Antidepressants (n, %)
Any	1724	68%	2792	59%	<0.0001	6274	67%	0.80	2733	62%	<0.0001	927	61%	<0.0001
Tricyclics	214	8%	494	11%	0.0036	941	10%	0.0099	363	8%	0.90	132	9%	0.74
Tetracyclics	118	5%	270	6%	0.043	590	6%	0.0013	228	5%	0.28	72	5%	0.87
SSRIs†	1127	44%	1922	41%	0.0071	4214	45%	0.35	1905	44%	0.62	622	41%	0.044
SNRIs‡	438	17%	618	13%	<0.0001	1587	17%	0.87	581	13%	<0.0001	225	15%	0.049
Miscellaneous	655	26%	914	19%	<0.0001	2488	27%	0.30	987	23%	0.0034	383	25%	0.75
Mood stabilizers (n, %)
Any	783	31%	814	17%	<0.0001	2365	25%	<0.0001	973	22%	<0.0001	424	28%	0.061
Carbamazepine	65	3%	117	2%	0.88	261	3%	0.49	143	3%	0.090	55	4%	0.050
Lamotrigine	239	9%	112	2%	<0.0001	571	6%	<0.0001	218	5%	<0.0001	118	8%	0.081
Lithium	209	8%	334	7%	0.094	728	8%	0.53	320	7%	0.19	121	8%	0.80
Oxcarbazepine	150	6%	156	3%	<0.0001	464	5%	0.069	168	4%	<0.0001	71	5%	0.10
Topiramate	214	8%	186	4%	<0.0001	652	7%	0.017	247	6%	<0.0001	122	8%	0.69
Valproate	4	0%	15	0%	0.20	25	0%	0.31	21	0%	0.030	5	0%	0.26

Note: p-value corresponds to aripiprazole vs comparator to left of p-value column.

*DCI = Charlson Comorbidity Index, Deyo Version.

†SSRIs = Selective serotonin reuptake inhibitors.

‡SNRIs = Serotonin norepinephrine reuptake inhibitors.

Table 4.  Second-generation antipsychotic treatment measures and incidence of psychiatric hospitalization.

	Aripiprazole (n = 2553)		Olanzapine (n = 4702)		p	Quetiapine (n = 9327)		p	Risperidone (n = 4377)		p	Ziprasidone (n = 1520)		p
Second-generation antipsychotic treatment measures (M, SD)
Days on therapy prior to psychiatric hospitalization or censoring	85	96	81	90	0.11	97	104	<0.0001	84	94	0.88	82	97	0.39
Starting dose	11.8	6.3	8.2	5.1		149	146		1.4	1.0		80.4	45.5
Maximum dose	13.7	7.2	9.6	5.8		194	184		1.7	1.1		94.4	50.2
Incidence of psychiatric hospitalization
Time to hospitalization
Person time at risk (M, SD)	85	96	81	90	0.11	97	104	<0.0001	85	94	0.87	82	97	0.40
Person time at risk (median)	34		35			51			34			30
Reason for end of follow-up (n, %)
Medical hospitalization	34	1%	79	2%	0.25	203	2%	0.0068	70	2%	0.38	19	1%	0.82
≥16 day gap in therapy	2109	83%	3748	80%	0.0028	7104	76%	<0.0001	3495	80%	0.0048	1210	80%	0.017
Addition of non-index second-generation antipsychotic	108	4%	296	6%	0.0002	393	4%	0.97	257	6%	0.0032	79	5%	0.15
Psychiatric hospitalization	139	5%	337	7%	0.0047	865	9%	<0.0001	292	7%	0.041	108	7%	0.032
Psychiatric hospitalization IR*	234		321		0.0026	349		<0.0001	288		0.053	315		0.019

Note: p-value corresponds to aripiprazole vs comparator to left of p-value column.

*IR = Incidence rate, reported as the number of events per 1000 patient years at risk.

Table 5.  Results of the multivariate analyses.

Time to psychiatric hospitalization				Costs of psychiatric hospitalization
Comparison	Hazard ratio	95% CI		Adjusted mean costs		Difference	95% CI
Aripiprazole vs Olanzapine	1.52	1.22	1.89	Aripiprazole = $127	Olanzapine = $155	$27	−$2	$50
Aripiprazole vs Quetiapine	1.40	1.17	1.68	Aripiprazole = $153	Quetiapine = $195	$42	$16	$66
Aripiprazole vs Risperidone	1.18	0.95	1.46	Aripiprazole = $150	Risperidone = $168	$18	−$13	$45
Aripiprazole vs Ziprasidone	1.33	1.02	1.73	Aripiprazole = $161	Ziprasidone = $177	$16	−$20	$51

Note: Cost measures are reported on a per-patient per-month basis.

Table 6.  Costs of psychiatric hospitalization.

Psychiatric hospitalization	Aripiprazole (n = 1622)		Olanzapine (n = 3058)		p	Quetiapine (n = 5746)		p	Risperidone (n = 2705)		p	Ziprasidone (n = 963)		p
Costs (M, SD)	$226	$881	$330	$1490	0.0027	$431	$1807	<0.0001	$350	$1575	0.0009	$351	$1499	0.019
Patients with psychiatric hospitalization (n, %)	344	21.2%	760	24.9%	0.0052	1566	27.3%	<0.0001	692	25.6%	0.0011	213	22.1%	0.59
Number of hospitalizations (M, SD)	0.3	0.8	0.4	0.9	0.0040	0.5	1.0	<0.0001	0.4	0.9	0.0031	0.4	1.0	0.24
Total days in hospital (M, SD)	1.6	5.4	2.2	11.8	0.026	2.4	6.8	<0.0001	2.2	6.3	0.0031	1.8	5.8	0.40
1 day (n, %)	34	2.1%	75	2.5%	0.44	132	2.3%	0.63	64	2.4%	0.56	22	2.3%	0.75
2–4 days (n, %)	122	7.5%	281	9.2%	0.053	503	8.8%	0.12	231	8.5%	0.24	78	8.1%	0.59
5–7 days (n, %)	87	5.4%	161	5.3%	0.89	367	6.4%	0.13	139	5.1%	0.75	41	4.3%	0.21
8+days (n, %)	101	6.2%	243	7.9%	0.032	564	9.8%	<0.0001	258	9.5%	0.0001	72	7.5%	0.22

Notes: p-value corresponds to aripiprazole vs comparator to left of p-value column; cost measures are reported on a per-patient per-month basis; utilization measures are reported for the entire follow-up period.