Association between second-generation antipsychotic medication half-life and hospitalization in the community treatment of adult schizophrenia

Figures & data

Table 1.  Background characteristics of schizophrenia patients treated with long and short half-life antipsychotic medications.

Characteristic		Long half-life (n = 1479)	Short half-life (n = 837)	p-value
Age (years)	Mean (SD)	40.5 (12.6)	40.6 (11.9)	0.82
Female	no. (%)	758 (51.3)	504 (60.2)	<0.001
Race		762 (51.5)	501 (59.9)	<0.001
White	no. (col%)
Black	no. (col%)	584 (39.5)	272 (32.5)
Other	no. (col%)	133 (9.0)	64 (7.6)
Medicaid coverage type		453 (30.6)	250 (29.9)	0.70
Capitated	no. (col%)
Fee-for-service	no. (col%)	1026 (69.4)	587 (70.1)
Blind/disabled	no. (%)	1345 (90.9)	748 (89.4)	0.22
With mental health/substance abuse coverage	no. (%)	1453 (98.2)	828 (98.9)	0.20
No of chronic conditions	Mean (SD)	2.5 (1.5)	2.9 (1.6)	<0.001
	Median	2	3

Table 2.  Baseline mental health service use for schizophrenia patients treated with long and short half-life antipsychotic medications.

Variable		Long half-life (n = 1479)	Short half-life (n = 837)	p-value
Index hospitalization LOS (days)	Mean (SD)	7.8 (8.1)	7.3 (7.2)	0.16
	Median	6	5
Psychiatric medication use*
Antidepressant	no. (%)	891 (60.2)	566 (67.6)	<0.001
Anti-anxiety agent	no. (%)	428 (28.9)	291 (34.8)	0.004
Anti-manic agent	no. (%)	504 (34.1)	342 (40.9)	0.001
Selected mental disorder*
Bipolar disorder	no. (%)	362 (24.5)	267 (31.9)	<0.001
Schizoaffective disorder	no. (%)	849 (57.4)	560 (66.9)	<0.001
Substance use disorder	no. (%)	182 (12.3)	140 (16.7)	0.003
Anxiety disorder	no. (%)	206 (13.9)	167 (20.0)	<0.001
Depression	no. (%)	589 (39.8)	404 (48.3)	<0.001
No. of ED visits with mental disorder(s)*	Mean (SD)	1.5 (1.5)	1.6 (1.7)	0.03

ED, emergency department; LOS, length of stay.

*Measured in the 6 months before index hospitalization.

Figure 1.  Rate of hospitalization for mental health disorders by days of therapy gap.

Table 3.  Years of follow-up and unadjusted outcomes, stratified by long and short half-life cohorts.

Variable		Long half-life (n = 1479)	Short half-life (n = 837)	n = 2316	p-value*
Follow-up years	Mean	0.65	0.62	0.64
	Total	959.9	518.8	1,478.7
Hospitalization/ED visits for mental disorder(s)	No.	523	362	885
	Events/PY†	0.74	1.06	0.85	<0.001
Hospitalization/ED visits for schizophrenia	No.	386	237	623
	Events/PY†	0.49	0.59	0.52	0.08
Hospitalization for mental disorder(s)	No.	318	214	532
	Events/PY†	0.38	0.52	0.43	0.005
Hospitalization for schizophrenia	No.	261	160	421
	Events/PY†	0.31	0.36	0.32	0.38
ED visits for mental disorder(s)	No.	1,002	741	1,743
	Events/PY†	1.04	1.43	1.18	<0.001
ED visits for schizophrenia	No.	489	303	792
	Events/PY†	0.51	0.58	0.54	0.23
Initiation of a second antipsychotic	No.	331	220	551
	Events/PY‡	0.34	0.42	0.37	0.02
Discontinuation of index therapy	No.	933	488	1,421
	Events/PY‡	0.97	0.94	0.96	0.99
Psychiatrist office visits	No.	6,211	2,958	9,169
	Events/PY‡	6.47	5.70	6.20	0.94
Outpatient contacts for mental disorder(s)	No.	49,489	21,564	71,053
	Events/PY‡	51.56	41.57	48.05	0.51

ED, emergency department; PY, patient-year.

*Adjusted with Holm’s step-down Bonferroni method.

†Observation period was censored once the first event occurred.

‡The entire follow-up period was used for observation; patients could have multiple events.

Table 4.  Adjusted* hazard ratio for hospitalization and emergency department visits among schizophrenia patients using long vs short half-life antipsychotics.

Event	Hazard ratio (95% CI)
Hospitalization/ED visits for mental disorder(s)	0.77 (0.67–0.88)†
Hospitalization/ED visits for schizophrenia	0.84 (0.71–0.997)‡
Hospitalization for mental disorder(s)	0.80 (0.67–0.96)‡
Hospitalization for schizophrenia	0.86 (0.70–1.05)

CI, confidence interval; ED, emergency department; LOS, length of stay.

*Adjusted by age, gender, race, payment type, blind/disabled, mental health/substance abuse coverage, year of index date, LOS of baseline hospitalization, number of chronic conditions, selected chronic conditions and psychiatric comorbidities (including bipolar disorders, schizoaffective disorders, substance use disorders, anxiety disorders, and depression), use of psychiatric medications (including antidepressants, anti-anxiety agents, and anti-manic agents), number of ED visits for mental disorders(s), number of outpatient contacts for mental disorder(s), and days of therapy gap.

†p < 0.001.

‡p < 0.05.