Measurement of treatment adherence with antipsychotic agents in patients with schizophrenia

Figures & data

Table 1 Patient characteristics (N = 18,425)

Sociodemographic characteristics (2002)	Mean + SD	%
Age, years	51.0 ± 10.7
Age groups, %:
≤44		26.1
45–49		21.8
50–54		24.5
55–59		11.5
≥60		16.1
Male, %		94.3
Race, %
White		48.1
Black		32.4
Hispanic		6.9
Others		12.7
Married, %		19.9
Clinical characteristics
Number of comorbid conditions
(2 years prior to initiation)
Total (mean + SD)	4.04 ± 2.4
Mental (mean ± SD)	2.23 ± 1.2
Physical (mean ± SD)	1.82 ± 1.9
Other clinical characteristics
(6 months prior to initiation)
Prior use of antidepressants, %		52.9
Prior use of mood stabilizers, %		12.4
Prior use of anxiolytics, %		42.9
Prior use of clozapine, %		2.4
% with at least one outpatient non-psychiatric visit		95.4
% with at least one outpatient psychiatric visit		96.3
% with at least one psychiatric hospitalization		32.3
% with at least one non-psychiatric hospitalization		15.9

Table 2 Number of patients with multiple medication episodes

Drug name	10/1/2002 to 3/31/2005
	Total	1 Episode		2 Episodes		3 + Episodes
	N	N	%	N	%	N	%
Atypical agents
Clozapine	271	250	92.3	14	5.2	7	2.6
Olanzapine	5,412	4,337	80.1	865	16.0	210	3.9
Quetiapine	7,412	6,093	82.2	1,071	14.5	248	3.3
Risperidone	7,482	6,060	81.0	1,125	15.0	297	4.0
Ziprasidone	2,323	2,033	87.5	244	10.5	46	2.0
Typical agents
Haloperidol	2,600	2,084	80.2	421	16.2	95	3.6
Perphenazine	414	255	80.2	51	16.0	12	3.8
Chlorpromazine	452	359	79.4	74	16.4	19	4.2

Table 3 Treatment persistence/medication compliance (using a gap of ≥ 30 days as discontinuation of medication) (10/1/2002 to 3/31/2005)

Drug name	1 Episode		2 Episodes			3 + Episodes				Treatment persistence	Medication possession ratio (MPR)	Medication compliance
	Mean ± SD	N	(1) Mean ± SD	(2) Mean ± SD	N	(1) Mean ± SD	(2) Mean ± SD	(3) Mean ± SD	N
Atypicals
Clozapine	255 ± 146	250	64 ± 65	170 ± 140	14	44 ± 49	46 ± 40	165 ± 166	6	240 ± 140	325 ± 252	254 ± 148
Olanzapine	171 ± 140	4,337	68 ± 57	130 ± 123	865	53 ± 39	50 ± 36	96 ± 97	179	151 ± 123	246 ± 228	176 ± 161
Quetiapine	186 ± 144	6,093	67 ± 55	143 ± 124	1,071	49 ± 36	50 ± 36	122 ± 113	218	165 ± 128	266 ± 315	191 ± 188
Risperidone	168 ± 140	6,060	69 ± 59	130 ± 122	1,125	53 ± 36	45 ± 31	94 ± 94	273	149 ± 124	241 ± 314	174 ± 165
Ziprasidone	172 ± 139	2,033	68 ± 58	154 ± 132	244	50 ± 37	43 ± 23	141 ± 123	42	151 ± 122	269 ± 113	178 ± 234
Typicals
Haloperidol	124 ± 128	2,084	54 ± 49	117 ± 116	421	44 ± 36	37 ± 25	73 ± 75	79	110 ± 112	197 ± 114	133 ± 168
Perphenazine	169 ± 136	255	69 ± 54	151 ± 137	51	61 ± 47	51 ± 20	51 ± 27	12	149 ± 119	239 ± 246	177 ± 165
Chlorpromazine	131 ± 126	359	59 ± 49	132 ± 127	74	65 ± 51	50 ± 44	80 ± 91	18	117 ± 110	234 ± 283	143 ± 170

Note: See text for explanation of shading.

Table 4 Medication episode-specific treatment adherence (using a gap of ≥30 days as discontinuation of medication)

Drug name	10/1/2002 to 3/31/2005
	1 Episode		2 Episodes		3 + Episodes
	Mean ± SD	N	Mean ± SD	N	Mean ± SD	N
Atypicals
Clozapine	255 ± 146	250	234 ± 205	14	255 ± 255	6
Olanzapine	171 ± 140	4,337	198 ± 180	865	199 ± 172	179
Quetiapine	186 ± 144	6,093	210 ± 179	1,071	221 ± 185	218
Risperidone	168 ± 140	6,060	199 ± 181	1,125	192 ± 161	273
Ziprasidone	172 ± 139	2,033	222 ± 190	244	184 ± 183	42
Typicals
Haloperidol	124 ± 128	2,084	171 ± 165	421	154 ± 136	79
Perphenazine	169 ± 136	255	220 ± 191	51	163 ± 153	12
Chlorpromazine	131 ± 126	359	191 ± 176	74	195 ± 186	18