Changes in Antipsychotic
Pharmacotherapy and Healthcare Costs
Following a New Diagnosis of Diabetes
among Patients with Schizophrenia
Douglas L. Leslie, PhD
Robert Rosenheck,
Rosenheck, MD
New England Mental Illness Research, Education and
Clinical Center (MIRECC);
VA Northeast Program Evaluation Center (NEPEC);
Yale Medical School
Background
FirstFirst-generation antipsychotics were introduced
in the 1950’
1950’s
SecondSecond-generation antipsychotics
–
–
–
–
clozapine, olanzapine, risperidone, quetiapine
At least as effective as firstfirst-generation drugs
Have fewer side effects
Associated with weight gain and diabetes
FDA warning
Objectives
To determine risk of newnew-onset diabetes
associated with antipsychotic medications.
To identify the costs associated with
treatment of newnew-onset diabetes.
Sample
Patients with schizophrenia treated in the VA
Healthcare System.
No prepre-existing diabetes.
“Stable”
Stable” on an antipsychotic medication.
To determine whether patients switch
antipsychotic medications after diagnosis
of diabetes.
Followed for up to 2 years between June 1999
and September 2001.
Methods
Study timeline
56,849 patients included in the study.
Patients with a new diagnosis of diabetes
were identified.
June 1999
September 2001
D
Diabetes patient
Cox proportional hazards model.
Stable period
(3 months)
A matched control group of patients who did
not develop diabetes was identified.
Medication changes and costs were
compared.
Diabetes
onset date
D
Matched nondiabetes patient
Stable period
(3 months)
Pseudo diabetes
onset date
1
Fitted survival functions from the Cox proportional
hazards model predicting time to diabetes onset
Results
1.00
Patients were followed for an average of
15.7 months
Unadjusted diabetes risk was highest for
clozapine and olanzapine
Total healthcare costs were $3,104 higher
for patients with diabetes
Percentage of patients who switch/discontinue
antipsychotic medication after diabetes onset
Last medication
before “diabetes date”
date”
clozapine
olanzapine
quetiapine
No
diabetes
9.8%
With
diabetes
4.6%
p
0.092
25.2%
23.1%
0.179
0.053
40.1%
31.9%
risperidone
28.2%
24.2%
0.023
conventional
24.3%
22.0%
0.097
Survival
4,132 patients had a new diagnosis of
diabetes – annual incidence rate of 4.36%
0.98
0.96
0.94
First-generation: ref
risperidone: HR=1.01
olanzapine: HR=1.15*
quetiapine: HR=1.20
clozapine: HR=1.57*
0.92
0.90
0.88
0
5
10
15
20
25
Month
Diabetes risk and costs attributable
to secondsecond-generation drugs
Average cost
per day of
therapy
Medication
clozapine
Attributable
risk
2.03%
Attributable
cost per day*
$0.134
olanzapine
0.63%
$0.042
$6.86
quetiapine
0.80%
$0.053
$3.72
risperidone
0.05%
$0.003
$3.65
$8.34
* Based on average cost of $198/month per case of diabetes
Conclusions
Very high rate of diabetes onset in this
population (4(4-5% per year)
Results do not support a “class effect”
effect”
Onset of diabetes does not affect
antipsychotic pharmacotherapy
Diabetes risk and treatment costs
attributable to secondsecond-generation drugs
are small
2