Patterns of relapse and associated cost burden in schizophrenia patients receiving atypical antipsychotics

Figures & data

Figure 1. (a) Study design scheme. (b) Identification of relapse episodes among relapsers.

Table 1. Baseline demographics and clinical characteristics.

	Relapsers (n = 9793)	Non-relapsers (n = 8343)	p-Value*
Age at index date, mean ± SD (median)	40.0 ± 10.0 (39.0)	40.8 ± 9.9 (40.0)	<0.0001
Age categories, n (%)
18–44 years	8131 (83.0)	6915 (82.9)	0.0025
45–64 years	1356 (13.8)	1093 (13.1)
≥65 years	306 (3.1)	335 (4.0)
Female, n (%)	5123 (52.3)	4504 (54.0)	0.0245
Race, n (%)
White	4808 (49.1)	4658 (55.8)	<0.0001
Black	3375 (34.5)	2276 (27.3)
Hispanic	543 (5.5)	475 (5.7)
Other	968 (9.9)	798 (9.6)
N/A	99 (1.0)	136 (1.6)
State, n (%)
Florida	2163 (22.1)	1655 (19.8)	<0.0001
Iowa	807 (8.2)	1025 (12.3)
Kansas	531 (5.4)	263 (3.2)
Missouri	3005 (30.7)	2776 (33.3)
New Jersey	3287 (33.6)	2624 (31.5)
Quan-Charlson Comorbidity Index, mean ± SD (median)	1.0 ± 1.7 (0.0)	0.9 ± 1.6 (0.0)	0.0575
Healthcare costs^a (US $2011), mean ± SD (median)
Pharmacy costs
All pharmacy costs	$3576 ± 5891 ($1318)	$4631 ± 6160 ($2631)	<0.0001
Typical and atypical AP medication costs	$1053 ± 1965 ($275)	$1440 ± 2315 ($444)	<0.0001
All medical costs
Inpatient costs	$5466 ± 15,015 (0)	$2087 ± 9854 (0)	<0.0001
Outpatient costs^b	$4928 ± 13,774 ($1048)	$3892 ± 11,356 ($944)	<0.0001
Emergency room costs	$611 ± 6474 ($7)	$235 ± 2352 (0)	<0.0001
Home visit costs	$1868 ± 12,476 (0)	$1324 ± 5617 (0)	0.0001
Long-term care costs	$3158 ± 16,368 (0)	$4284 ± 16,907 (0)	<0.0001
Mental institute costs	$3087 ± 21,022 (0)	$2506 ± 21,862 (0)	0.0696
Other medical ancillary costs^c	$1567 ± 9816 (0)	$3321 ± 15,823 ($40)	<0.0001
Schizophrenia-related medical costs^d
Inpatient costs	$872 ± 5584 (0)	$436 ± 4577 (0)	<0.0001
Outpatient costs^b	$580 ± 5039 (0)	$365 ± 3494 (0)	0.0008
Emergency room costs	$98 ± 2328 (0)	$51 ± 1721 (0)	0.1240
Home visit costs	$49 ± 1307 (0)	$67 ± 737 (0)	0.2441
Long-term care costs	$138 ± 2812 (0)	$582 ± 6497 (0)	<0.0001
Mental institute costs	$575 ± 8793 (0)	$767 ± 6136 (0)	0.0850
Other medical ancillary service costs^c	$63 ± 1476 (0)	$97 ± 1144 (0)	0.0793
Schizophrenia-related pharmacy and medical costs^d	$3427 ± 12,608 ($720)	$3805 ± 11,121 ($1119)	0.0317
Total pharmacy and medical costs	$24,260 ± 41,012 ($9984)	$22,280 ± 35,641 ($11,401)	0.0005
Weekly costs^a (US $2011), mean ± SD (median)
Total baseline weekly cost	$467 ± 789 ($192)	$428 ± 685 ($219)	0.0005
Weekly maintenance cost^e	$425 ± 791 ($148)	$414 ± 689 ($203)	0.2963
Observation period, days, mean ± SD (median)	2063 ± 1020 (1812)	2030 ± 991 (1798)	0.0311
Days between 1st atypical AP prescription and index date, mean ± SD (median)	357 ± 558 (95)	477 ± 649 (192)	<0.0001

P25, 25th percentile; P75, 75th percentile.

*Statistical differences between cohorts were calculated using Chi-squared tests for categorical variables (where the possible values for the categorical variables are regrouped using brackets) and two-sided Student’s t-tests for continuous variables.

^aEvaluated during the baseline period, defined as 12 months before the index date.

^bOutpatient costs included costs associated with services not categorized as institutional visits, home visits, or other medical ancillary services.

^cOther medical ancillary service costs included costs associated with dental services, rehabilitation, substance abuse care, group/foster care, and in-community services.

^dSchizophrenia-related services or costs were defined as claims associated with a diagnosis for schizophrenia.

^eWeekly maintenance cost was defined as the mean weekly cost during baseline, excluding the weeks before, during, and after initiation of AP medication, and weeks with schizophrenia-related hospitalizations or emergency department costs. This is the baseline cost used in identification of relapsers, relapse episodes, and cost drivers of relapse.

Table 2. Patterns of relapse episodes.

	Relapsers (n = 9793)
Episode patterns*
Number of episodes, mean ± SD; median (P25–P75)	9.0 ± 12; 5 (2–11)
1 episode, n (%)	1634 (17)
2 episodes, n (%)	1160 (12)
3–5 episodes, n (%)	2591 (26)
6–9 episodes, n (%)	1956 (20)
≥10 episodes, n (%)	2452 (25)
Duration of episodes (weeks), mean ± SD; median (P25–P75)	10.6 ± 40; 2 (1–5)
1st episode	34.2 ± 90; 4 (1–14)
2nd episode	14.9 ± 43; 3 (1–9)
3rd episode	12.5 ± 39; 2 (1–7)
4th episode	10.9 ± 34; 2 (1–6)
5th episode	10.4 ± 32; 2 (1–6)
Excluding 1st episode	7.6 ± 27; 1 (1–4)
Weekly cost per episode (US $2011), mean ± SD; median (P25–P75)	$2884 ± 4024; 1658 (539–3971)
1st episode	$3308 ± 5433; 1921 (506–4377)
2nd episode	$3027 ± 5158; 1708 (438–3990)
3rd episode	$2963 ± 5478; 1645 (404–3986)
4th episode	$3064 ± 6110; 1565 (372–3991)
5th episode	$2915 ± 5085; 1477 (359–4072)
Excluding 1st episode	$1482 ± 3424; 499 (198–1558)
Total healthcare cost per episode (US $2011), mean ± SD; median (P25–P75)	$35,725 ± 108,403; 9015 (4567–20,684)
1st episode	$35,323 ± 116,714; 7812 (3523–18,206)
2nd episode	$19,578 ± 72,888; 5511 (2038–12,364)
3rd episode	$17,603 ± 83,389; 4992 (1664–11,156)
4th episode	$15,235 ± 67,706; 4688 (1405–10,219)
5th episode	$13,578 ± 52,364; 4491 (1269–9657)
Excluding 1st episode	$11,293 ± 50,765; 4259 (1173–8345)
Number of weeks between episodes, mean ± SD; median (P25–P75)	12.5 ± 27; 3 (2–10)
Number of weeks between index date and first episode, mean ± SD; median (P25–P75)	10.9 ± 21; 0 (0–11)

P25, 25th percentile; P75, 75th percentile.

* Evaluated during the observation period defined from the index date to the end of eligibility.

Table 3. Resource utilization between baseline and relapse episodes.

	Incidence rate (number of events/person-year)		Univariate incidence rate ratio* (95% CI)	p-Value
	Baseline period	Relapse episodes
Pharmacy claims
All pharmacy claims	36.18	70.68	2.02 (1.96–2.07)	<0.0001
AP claims	4.34	14.15	3.22 (3.10–3.35)	<0.0001
All medical services
Institutional visits	8.68	19.45	2.44 (2.33–2.56)	<0.0001
Inpatient admissions	1.11	2.80	3.37 (3.15–3.60)	<0.0001
Inpatient days	8.94	21.19	3.12 (2.91–3.34)	<0.0001
Emergency room visits	3.09	3.72	1.41 (1.28–1.55)	<0.0001
Long-term care admissions	0.50	1.31	3.12 (2.69–3.61)	<0.0001
Long-term care days	13.20	47.15	3.59 (3.00–4.29)	<0.0001
Mental institute admissions	3.98	11.61	2.93 (2.75–3.12)	<0.0001
Mental institute days	13.95	49.03	3.49 (2.96–4.13)	<0.0001
Outpatient visits^a	19.55	33.30	1.86 (1.78–1.95)	<0.0001
Home visits	4.74	12.22	2.65 (2.36–2.98)	<0.0001
Other medical ancillary services^b	1.04	1.34	1.34 (1.24–1.45)	<0.0001
Schizophrenia-related medical services^c
Institutional visits	1.32	8.97	6.68 (6.03–7.40)	<0.0001
Inpatient admissions	0.15	1.13	8.78 (7.64–10.09)	<0.0001
Inpatient days	1.57	8.80	14.51 (12.06–17.46)	<0.0001
Emergency room visits	0.25	0.28	1.55 (0.98–2.45)	0.0598
Long-term care admissions	0.04	0.22	5.54 (3.48–8.81)	<0.0001
Long-term care days	0.66	9.77	128.42 (79.82–206.61)	<0.0001
Mental institute admissions	0.87	7.34	8.03 (7.17–9.00)	<0.0001
Mental institute days	3.00	28.79	18.15 (15.58–21.15)	<0.0001
Outpatient visits^a	0.93	5.91	6.68 (5.98–7.47)	<0.0001
Home visits	0.15	2.04	13.05 (8.33–20.45)	<0.0001
Other medical ancillary services^b	0.02	0.13	5.47 (3.32–9.02)	<0.0001

*Statistical differences between groups, as well as 95% confidence intervals (95% CIs), were calculated using conditional Poisson regression models.

^aOutpatient visits included services not categorized as institutional visits, home visits, or other medical ancillary services.

^bOther medical ancillary services included dental services, rehabilitation, substance abuse care, group/foster care, and in-community services.

^cSchizophrenia-related services or costs were defined as claims associated with a diagnosis for schizophrenia.

Figure 2. (a) Mean cost difference and (b) Stratified mean cost difference per week between baseline and relapse episodes. CD, Cost difference; Ep, Episode. *Cost difference was calculated as the difference between relapse episodes and maintenance baseline mean weekly costs. Confidence intervals were calculated using bootstrap procedures and are not symmetric around the means. Percentages were calculated on the basis of non-rounded numbers. †Schizophrenia-related costs were defined as claims associated with a diagnosis for schizophrenia. Typical and atypical AP medications were used to define schizophrenia-related pharmacy costs. ‡Outpatient costs included costs associated with services not categorized as institutional visits, home visits, or other medical ancillary services. §Other medical ancillary service costs included costs associated with dental services, rehabilitation, substance abuse care, group/foster care, and in-community services.