Are African American patients at a higher risk for olanzapine-induced glucose intolerance?

Impact of race on efficacy and safety during treatment with olanzapine in schizophrenia, schizophreniform or schizoaffective disorder

BACKGROUND

To examine potential differences in efficacy and safety of treatment with olanzapine in patients with schizophrenia of white and black descent.

METHODS

A post-hoc, pooled analysis of 6 randomized, double-blind trials in the treatment of schizophrenia, schizophreniform disorder, or schizoaffective disorder compared white (N = 605) and black (N = 375) patients treated with olanzapine (5 to 20 mg/day) for 24 to 28 weeks. Efficacy measurements included the Positive and Negative Syndrome Scale (PANSS) total score; and positive, negative, and general psychopathology scores; and the Clinical Global Impression of Severity (CGI-S) scores at 6 months. Safety measures included differences in the frequencies of adverse events along with measures of extrapyramidal symptoms, weight, glucose, and lipid changes over time.

RESULTS

51% of black patients and 45% of white patients experienced early study discontinuation (P = .133). Of those who discontinued, significantly more white patients experienced psychiatric worsening (P = .002) while significantly more black patients discontinued for reasons other than efficacy or tolerability (P = .014). Discontinuation for intolerability was not different between groups (P = .320). For the estimated change in PANSS total score over 6 months, there was no significant difference in efficacy between white and black patients (P = .928), nor on the estimated PANSS positive (P = .435), negative (P = .756) or general psychopathology (P = .165) scores. Overall, there was no significant difference in the change in CGI-S score between groups from baseline to endpoint (P = .979). Weight change was not significantly different in white and black patients over 6 months (P = .127). However, mean weight change was significantly greater in black versus white patients at Weeks 12 and 20 only (P = .028 and P = .026, respectively). Additionally, a significantly greater percentage of black patients experienced clinically significant weight gain (≥ 7%) at anytime compared to white patients (36.1% vs. 30.4%, P = .021). Changes across metabolic parameters (combined fasting and random lipids and glucose) were also not significantly different between groups, with the exception of a greater categorical change in total cholesterol from borderline to high among white subjects and a categorical change from normal to low in high density lipoprotein (HDL) cholesterol among white males.

CONCLUSIONS

The findings did not demonstrate overall substantive differences in efficacy or safety between white and black patients diagnosed with schizophrenia or related disorders treated with olanzapine. However, a significantly greater percentage of black patients (36.1%) experienced clinically significant weight gain compared to white patients (30.4%).

Atypical antipsychotics and diabetes mellitus

Recently, increasing attention has been drawn to the potential diabetogenic effect of novel antipsychotics. Until now, large prospective studies examining the relationship between atypical antipsychotics and impaired glucose metabolism have been lacking. However, the case reports and retrospective studies that we review here suggest an increased risk of developing diabetes mellitus (DM) in patients treated with atypical antipsychotics compared to schizophrenic patients treated with conventional antipsychotics or those without treatment. Although most atypical antipsychotic agents might have a diabetogenic potential, the risk of developing DM might be higher in patients treated with either clozapine or olanzapine than with risperidone, whereas data on quetiapine and ziprasidone is presently limited and needs further attention. Possible mechanisms include the induction of peripheral insulin resistance and the direct influence on pancreatic beta-cell function by 5-HT1A/2A/2C receptor antagonism, by inhibitory effects via alpha 2-adrenergic receptors or by toxic effects. On the other hand, atypical antipsychotics might not be an independent risk factor for the development of DM, but hasten the onset of DM in patients bearing other risk factors. It is suggested that schizophrenic patients should be monitored for the occurrence of glucose metabolism abnormalities before starting atypical antipsychotics, and at a 3-month interval at least during therapy.

Atypical antipsychotic agents and increased risk of diabetes: class action or differential action?

Atypical antipsychotic (AAP) agents are useful in treating patients with schizophrenia and other psychosis. Their advantages are the low incidence of extrapyramidal side effects, and possible amelioration of negative, cognitive and mood symptoms. Occurrence of diabetes after AAP drug administration is of concern as patients do not often recognise their symptoms, physicians may fail to diagnose early, with consequent morbidity and mortality. The symptoms of psychosis, including lack of insight and motivation, may decrease the ability of schizophrenic patients to communicate potential health problems. Whether or not AAP drugs induce diabetes and, if they do, if it is a class action or a differential action, is often debated. Clinical evidence on AAP drug-induced diabetes is mounting. With their discontinuation, the diabetes often dissipates, but reappears when they are started again, thereby implicating the AAP drugs in the development of diabetes. There is still dispute regarding the differential effect of the various AAP drugs in their ability to produce diabetes. Although not scientifically proven, available evidence seems to indicate that clozapine and olanzapine may have a higher propensity to induce diabetes compared with other AAP drugs.

Antipsychotic exposure and type 2 diabetes among patients with schizophrenia: a matched case-control study of California Medicaid claims

PURPOSE

To examine the risk of developing type 2 diabetes mellitus among people with schizophrenia exposed to atypical antipsychotics (clozapine, olanzapine, quetiapine, risperidone) compared to those exposed to conventional antipsychotics.

METHODS

A matched case-control design was used to examine California Medicaid beneficiaries. Cases developed diabetes subsequent to being diagnosed with schizophrenia (ICD-9295), were 18 years or older, and were exposed to at least one antipsychotic medication at some point during the 12 weeks preceding diabetes diagnosis. Diabetes was defined by diagnostic claim (ICD-9250) or prescription for antidiabetic agents. A total of 3663 cases were matched to 14 523 non-diabetic controls (people with schizophrenia matched on gender and age +/-5 years). All had to be continuously eligible for benefits during the 12-week period preceding diabetes onset in the case. Conditional logistic regression modeled the risk of exposure, controlling for age, ethnicity, and exposure to selected concomitant medications. Analyses were repeated with 24- and 52-week exposure windows.

RESULTS

Using a 12-week exposure window, olanzapine (OR = 1.36, 95%CI 1.20-1.53), clozapine (OR = 1.34, 95%CI 1.16-1.55), and combination atypical therapy (OR = 1.58, 95%CI 1.33-1.88), but not risperidone or quetiapine, were associated with increased odds of developing diabetes compared to conventional antipsychotics. Changing to a 24-week exposure window, the risks were: olanzapine (OR = 1.38, 95%CI 1.22-1.56), clozapine (OR = 1.32, 95%CI 1.14-1.53), or combinations (OR = 1.54, 95%CI 1.29-1.84). With a 52-week exposure window, the risks were: olanzapine (OR = 1.41, 95%CI 1.24-1.60), clozapine (OR = 1.41, 95%CI 1.21-1.65), combinations (OR = 1.58, 95%CI 1.31-1.90). Risk for olanzapine increased with dose. Hispanic, African American, and unknown ethnicity were significant risks for development of type 2 diabetes as was exposure to selected concomitant medications.

CONCLUSIONS

Exposure to olanzapine or clozapine is associated with a 34-41% increase in the developing of type 2 diabetes among California Medicaid recipients with schizophrenia. Prospective, randomized trials are needed to confirm these retrospective, observational findings.

Adverse Metabolic Effects Associated with Atypical Antipsychotics

Adverse metabolic effects, such as diabetes mellitus, lipid abnormalities and weight gain, have increasingly been recognised with the use of the newer, so-called atypical antipsychotic drugs. This article reviews the current literature in the field and attempts to answer the question of whether the atypical antipsychotics differ in their effects on glucose-insulin homeostasis and lipid metabolism. It also addresses how then to manage the use of the atypical antipsychotics that do interfere with these metabolic systems. Differences in effects of atypical antipsychotics on leptin levels are also summarised and put into context; bodyweight gain associated with atypical antipsychotics is reviewed elsewhere. In summary, there are no large controlled trials published quantifying the prevalence of adverse effects on glucose-insulin homeostasis and lipid metabolism in patients receiving atypical antipsychotics. Nevertheless, the published articles and case reports reviewed in this article give a fairly good view of those adverse effects occurring with clozapine, olanzapine and risperidone, whereas little data are available regarding quetiapine, ziprasidone and zotepine, and no data exist for amisulpride and aripiprazole. Estimated rankings of the atypical agents, based on the available literature, show that the relative risk of glucose intolerance/diabetes mellitus, hyperlipidaemia and hyperleptinaemia is highest for clozapine and olanzapine, moderately high for quetiapine, rather low for risperidone and lowest for ziprasidone. Since adverse metabolic effects of atypical antipsychotics may have a negative influence on both the antipsychotic treatment outcome as well as the physical health of the patient, these effects have to be recognised and adequately managed. In this review, recommendations for prevention and treatment of the adverse metabolic effects are outlined.