The effects of clozapine on symptom clusters in treatment-refractory patients

Clozapine dose for schizophrenia

BACKGROUND

Schizophrenia and related disorders such as schizophreniform and schizoaffective disorder are serious mental illnesses characterised by profound disruptions in thinking and speech, emotional processes, behaviour and sense of self. Clozapine is useful in the treatment of schizophrenia and related disorders, particularly when other antipsychotic medications have failed. It improves positive symptoms (such as delusions and hallucinations) and negative symptoms (such as withdrawal and poverty of speech). However, it is unclear what dose of clozapine is most effective with the least side effects.

OBJECTIVES

To compare the efficacy and tolerability of clozapine at different doses and to identify the optimal dose of clozapine in the treatment of schizophrenia, schizophreniform and schizoaffective disorders.

SEARCH METHODS

We searched the Cochrane Schizophrenia Group's Study-Based Register of Trials (August 2011 and 8 December 2016).

SELECTION CRITERIA

All relevant randomised controlled trials (RCTs), irrespective of blinding status or language, that compared the effects of clozapine at different doses in people with schizophrenia and related disorders, diagnosed by any criteria.

DATA COLLECTION AND ANALYSIS

We independently inspected citations from the searches, identified relevant abstracts, obtained full articles of relevant abstracts, and classified trials as included or excluded. We included trials that met our inclusion criteria and reported useable data. For dichotomous data, we calculated the relative risk (RR) and the 95% confidence interval (CI) on an intention-to-treat basis based on a random-effects model. For continuous data, we calculated mean differences (MD) again based on a random-effects model. We assessed risk of bias for included studies and created 'Summary of findings' tables using GRADE.

MAIN RESULTS

We identified five studies that could be included. Each compared the effects of clozapine at very low dose (up to 149 mg/day), low dose (150 mg/day to 300 mg/day) and standard dose (301 mg/day to 600 mg/day). Four of the five included studies were based on a small number of participants. We rated all the evidence reported for the main outcomes of interest as low or very low quality. No data were available for the main outcomes of global state, service use or quality of life. Very low dose compared to low doseWe found no evidence of effect on mental state between low and very low doses of clozapine in terms of average Brief Psychiatric Rating Scale-Anchored (BPRS-A) endpoint score (1 RCT, n = 31, MD 3.55, 95% CI -4.50 to 11.60, very low quality evidence). One study found no difference between groups in body mass index (BMI) in the short term (1 RCT, n = 59, MD -0.10, 95% CI -0.95 to 0.75, low-quality evidence). Very low dose compared to standard doseWe found no evidence of effect on mental state between very low doses and standard doses of clozapine in terms of average BPRS-A endpoint score (1 RCT, n = 31, MD 6.67, 95% CI -2.09 to 15.43, very low quality evidence). One study found no difference between groups in BMI in the short term (1 RCT, n = 58, MD 0.10, 95% CI -0.76 to 0.96, low-quality evidence) Low dose compared to standard doseWe found no evidence of effect on mental state between low doses and standard doses of clozapine in terms of both clinician-assessed clinical improvement (2 RCTs, n = 141, RR 0.76, 95% CI 0.36 to 1.61, medium-quality evidence) and clinically important response as more than 30% change in BPRS score (1 RCT, n = 176, RR 0.93, 95% CI 0.78 to 1.10, medium-quality evidence). One study found no difference between groups in BMI in the short term (1 RCT, n = 57, MD 0.20, 95% CI -0.84 to 1.24, low-quality evidence).We found some evidence of effect for other adverse effect outcomes; however, the data were again limited. Very low dose compared to low doseThere was limited evidence that serum triglycerides were lower at low-dose clozapine compared to very low dose in the short term (1 RCT, n = 59, MD 1.00, 95% CI 0.51 to 1.49). Low dose compared to standard doseWeight gain was lower at very low dose compared to standard dose (1 RCT, n = 27, MD -2.70, 95% CI -5.38 to -0.02). Glucose level one hour after meal was also lower at very lose dose (1 RCT, n = 58, MD -1.60, 95% CI -2.90 to -0.30). Total cholesterol levels were higher at very low compared to standard dose (1 RCT, n = 58, n = 58, MD 1.00, 95% CI 0.20 to 1.80). Low dose compared to standard doseThere was evidence of fewer adverse effects, measured as lower TESS scores, in the low-dose group in the short term (2 RCTs, n = 266, MD -3.99, 95% CI -5.75 to -2.24); and in one study there was evidence that the incidence of lethargy (RR 0.77, 95% CI 0.60 to 0.97), hypersalivation (RR 0.70, 95% CI 0.57 to 0.84), dizziness (RR 0.56, 95% CI 0.39 to 0.81) and tachycardia (RR 0.57, 95% CI 0.45 to 0.71) was less at low dose compared to standard dose.

AUTHORS' CONCLUSIONS

We found no evidence of effect on mental state between standard, low and very low dose regimes, but we did not identify any trials on high or very high doses of clozapine. BMI measurements were similar between groups in the short term, although weight gain was less at very low dose compared to standard dose in one study. There was limited evidence that the incidence of some adverse effects was greater at standard dose compared to lower dose regimes. We found very little useful data and the evidence available is generally of low or very low quality. More studies are needed to validate our findings and report on outcomes such as relapse, remission, social functioning, service utilisation, cost-effectiveness, satisfaction with care, and quality of life. There is a particular lack of medium- or long-term outcome data, and on dose regimes above the standard rate.

Clozapine versus typical neuroleptic medication for schizophrenia

BACKGROUND

Long-term drug treatment of schizophrenia with typical antipsychotics has limitations: 25 to 33% of patients have illnesses that are treatment-resistant. Clozapine is an antipsychotic drug, which is claimed to have superior efficacy and to cause fewer motor adverse effects than typical drugs for people with treatment-resistant illnesses. Clozapine carries a significant risk of serious blood disorders, which necessitates mandatory weekly blood monitoring at least during the first months of treatment.

OBJECTIVES

To evaluate the effects of clozapine compared with typical antipsychotic drugs in people with schizophrenia.

SEARCH STRATEGY

For the current update of this review (March 2006) we searched the Cochrane Schizophrenia Group Trials Register.

SELECTION CRITERIA

All relevant randomised clinical trials (RCTs).

DATA COLLECTION AND ANALYSIS

We extracted data independently. For dichotomous data we calculated relative risks (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis, based on a fixed-effect model. We calculated numbers needed to treat/harm (NNT/NNH) where appropriate. For continuous data, we calculated weighted mean differences (WMD) again based on a fixed-effect model.

MAIN RESULTS

We have included 42 trials (3950 participants) in this review. Twenty-eight of the included studies are less than 13 weeks in duration, and, overall, trials were at significant risk of bias. We found no significant difference in the effects of clozapine and typical neuroleptic drugs for broad outcomes such as mortality, ability to work or suitability for discharge at the end of the study. Clinical improvements were seen more frequently in those taking clozapine (n=1119, 14 RCTs, RR 0.72 CI 0.7 to 0.8, NNT 6 CI 5 to 8). Also, participants given clozapine had fewer relapses than those on typical antipsychotic drugs (n=1303, RR 0.62 CI 0.5 to 0.8, NNT 21 CI 15 to 49). BPRS scores showed a greater reduction of symptoms in clozapine-treated patients, (n=1145, 16 RCTs, WMD -4.22 CI -5.4 to -3.1), although the data were heterogeneous (Chi(2) 0.0001, I(2) 66%). Short-term data from the SANS negative symptom scores favoured clozapine (n=196, 5 RCTs, WMD -5.92 CI -7.8 to -4.1). We found clozapine to be more acceptable in long-term treatment than conventional antipsychotic drugs (n=982, 16 RCTs, RR 0.60 CI 0.5 to 0.7, NNT 15 CI 12 to 20). Blood problems occurred more frequently in participants receiving clozapine (3.2%) compared with those given typical antipsychotics (0%) (n=1031, 13 RCTs, RR 7.09 CI 2.0 to 25.6). Clozapine participants experienced more drowsiness, hypersalivation, or temperature increase, than those given conventional neuroleptics. However, clozapine patients experienced fewer motor adverse effects (n=1433, 18 RCTs, RR 0.58 CI 0.5 to 0.7, NNT 5 CI 4 to 6).The clinical effects of clozapine were more pronounced in participants resistant to typical neuroleptics in terms of clinical improvement (n=370, 4 RCTs, RR 0.71 CI 0.6 to 0.8, NNT 4 CI 3 to 6) and symptom reduction. Thirty-four per cent of treatment-resistant participants had a clinical improvement with clozapine treatment.

AUTHORS' CONCLUSIONS

Clozapine may be more effective in reducing symptoms of schizophrenia, producing clinically meaningful improvements and postponing relapse, than typical antipsychotic drugs - but data are weak and prone to bias. Participants were more satisfied with clozapine treatment than with typical neuroleptic treatment. The clinical effect of clozapine, however, is, at least in the short term, not reflected in measures of global functioning such as ability to leave the hospital and maintain an occupation. The short-term benefits of clozapine have to be weighed against the risk of adverse effects. Within the context of trials, the potentially dangerous white blood cell decline seems to be more frequent in children and adolescents and in the elderly than in young adults or people of middle-age.The existing trials have largely neglected to assess the views of participants and their families on clozapine. More community-based long-term randomised trials are needed to evaluate the efficacy of clozapine on global and social functioning as trials in special groups such as people with learning disabilities.

Symptom Clusters

The purpose of this article is to analyze the concept of symptom clusters and to discuss its application to cancer nursing to promote communication and enhance scientific knowledge. Rodgers' evolutionary method of concept analysis served as the framework for reviewing literature from psychology/psychiatry, general medicine, and nursing. Attributes of symptom clusters were relationships of symptoms and relationships of clusters, concurrence, underlying dimensions, stability, and common etiology. The major antecedent was the presence of 2 or more symptoms. Consequences were poorer physical health status, interference with activities of daily living, emotional distress, and increased financial burden. A symptom cluster is defined as consisting of 2 or more symptoms that are related to each other and that occur together. Symptom clusters are composed of stable groups of symptoms, are relatively independent of other clusters, and may reveal specific underlying dimensions of symptoms. Relationships among symptoms within a cluster should be stronger than relationships among symptoms across different clusters. Symptoms in a cluster may or may not share the same etiology. Symptom should be broadened to include both subjective (self-reported) symptoms and objective (observed) signs. Implications for researchers include the need to use a clear definition, determine the optimal methods of identifying etiology and nature of symptom clusters in various populations, assess the clinical utility of symptom clusters, and test interventions. Implications for practitioners include the need to comprehensively assess symptoms over the entire cancer trajectory, select interventions that target single and multiple symptoms, and evaluate outcomes that include quality of life and economic variables.

The effect of quetiapine on aggression and hostility in patients with schizophrenia

A post hoc analysis of data from three placebo-controlled, double-blind, randomized trials was carried out to determine the efficacy of quetiapine in aggression and hostility in patients with schizophrenia. Quetiapine treatment induced statistically significantly greater improvements in BPRS positive symptom cluster scores and three measures of hostility derived from the BPRS, compared with placebo, in patients symptomatic at baseline. A path analysis showed that the improvements in hostility were highly correlated with improvements in positive symptoms and there was no consistent relationship between sedation and hostility. Aggressive behaviour appears to be related to positive symptoms of schizophrenia. Quetiapine may be a suitable option for patients with schizophrenia and aggressive behaviour.

An analysis of the effect of funding source in randomized clinical trials of second generation antipsychotics for the treatment of schizophrenia

OBJECTIVE

The effect of funding source on the outcome of randomized controlled trials has been investigated in several medical disciplines; however, psychiatry has been largely excluded from such analyses. In this article, randomized controlled trials of second generation antipsychotics in schizophrenia are reviewed and analyzed with respect to funding source (industry vs. non-industry funding).

METHOD

A literature search was conducted for randomized, double-blind trials in which at least one of the tested treatments was a second generation antipsychotic. In each study, design quality and study outcome were assessed quantitatively according to rating scales. Mean quality and outcome scores were compared in the industry-funded studies and non-industry-funded studies. An analysis of the primary author's affiliation with industry was similarly performed.

RESULTS

Results of industry-funded studies significantly favored second generation over first generation antipsychotics when compared to non-industry-funded studies. Non-industry-funded studies showed a trend toward higher quality than industry-funded studies; however, the difference between the two was not significant. Also, within the industry-funded studies, outcomes of trials involving first authors employed by industry sponsors demonstrated a trend toward second generation over first generation antipsychotics to a greater degree than did trials involving first authors employed outside the industry (p=0.05).

CONCLUSIONS

While the retrospective design of the study limits the strength of the findings, the data suggest that industry bias may occur in randomized controlled trials in schizophrenia. There appears to be several sources by which bias may enter clinical research, including trial design, control of data analysis and multiplicity/redundancy of trials.

A comparison of drug effects in latent inhibition and the forced swim test differentiates between the typical antipsychotic haloperidol, the atypical antipsychotics clozapine and olanzapine, and the antidepressants imipramine and paroxetine

Current animal models of antipsychotic activity that have the capacity to dissociate between typical and atypical antipsychotic drugs (APDs) have two drawbacks: they require previous administration of a psychotomimetic drug, and they achieve the dissociation by demonstrating effectiveness of atypical but not typical APDs, thus losing specificity and selectivity for APDs. The present experiments were designed to solve these problems by using two non-pharmacological tests: latent inhibition (LI), in which potentiation of the deleterious effects of non-reinforced stimulus pre-exposure on its subsequent conditioning served as a behavioral index for a common action of typical and atypical APDs (antipsychotic), and the forced swim test (FST), in which reduction of immobility served as a behavioral index for a dissimilar action of these drugs (antidepressant). The typical APD haloperidol (0.1 mg/kg), the atypical APDs clozapine (2.5 mg/kg) and olanzapine (0.6 mg/kg), and the antidepressants imipramine (10 mg/kg) and paroxetine (7.0 mg/kg), produced distinct patterns of action in the two tests: haloperidol potentiated LI and increased immobility in the FST, clozapine and olanzapine potentiated LI and decreased immobility in the FST, and imipramine and paroxetine decreased immobility in the FST and did not potentiate LI. Thus, the comparison of drug effects in LI and FST enabled a discrimination between typical and atypical APDs without losing selectivity for APDs.

Clozapine versus typical neuroleptic medication for schizophrenia

BACKGROUND

Long-term drug treatment of schizophrenia with conventional antipsychotics has limitations: 25-33% of patients have illnesses that are treatment-resistant. Clozapine is an atypical antipsychotic drug, which is claimed to have superior efficacy and to cause fewer motor adverse effects than typical drugs for people with treatment-resistant illnesses. Clozapine carries a significant risk of serious blood disorders, which necessitates mandatory weekly blood monitoring at least during the first months of treatment.

OBJECTIVES

To evaluate the effects of clozapine for schizophrenia in comparison to typical antipsychotic drugs.

SEARCH STRATEGY

Publications in all languages were searched from the following databases: Biological Abstracts (1982-1999), The Cochrane Library CENTRAL (Issue 2, 1999), Cochrane Schizophrenia Group's Specialised Register (1999), EMbase (1980-1999), ISI Citation Index, LILACS (1982-1999), MEDLINE (1966-1999), and PsycLIT (1974-1999). Reference list screening of included papers was performed. Authors of recent trials and the manufacturer of clozapine contacted.

SELECTION CRITERIA

All randomised controlled trials comparing clozapine with typical antipsychotic drugs were included by independent assessment by at least two reviewers.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by at least two reviewers. Authors of trials published since 1980 were contacted for additional and missing data. Odds ratios (OR) and 95% confidence intervals (CI) of homogeneous dichotomous data were calculated with the Peto method. A random effects model was used for heterogeneous dichotomous data. Where possible the numbers needed to treat (NNT) or needed to harm (NNH) were also calculated. Weighted or standardised means were calculated for continuous data.

MAIN RESULTS

Currently the review includes 31 studies, 26 of which are less than 13 weeks in duration. These studies include 2589 participants, most of whom were men (74%). The average age was 38 years. There was no difference in the effects of clozapine and typical neuroleptic drugs for broad outcomes such as mortality, ability to work or suitability for discharge at end of the study. Clinical improvement was seen more frequently in those taking clozapine (random effects OR 0.4 CI 0.2-0.6, NNT 6) both in the short and the long term. Also, in the short term, participants on clozapine had fewer relapses than those on typical antipsychotic drugs (OR 0.6 CI 0.4-0.8, NNT 20 CI 17-38), and this may be true for long-term treatment as well. Symptom assessment scales showed a greater reduction of symptoms in clozapine-treated patients. Clozapine treatment was more acceptable than low-potency antipsychotics such as chlorpromazine (OR 0.6 CI 0.4-0.9) but did not differ from acceptability of high-potency neuroleptics such as haloperidol (random effects OR 0.8 CI 0.4-1.5). Clozapine was more acceptable in long-term treatment than conventional antipsychotic drugs (random effects OR 0.4 CI 0.2-0.7, NNT 6 CI 3-111). Patients were more satisfied with clozapine treatment (OR 0.5 CI 0.3-0.8, NNT 12 CI 7-37), but they experienced more hypersalivation, temperature increase, and drowsiness than those given conventional neuroleptics. However, clozapine patients experience fewer motor side effects and less dry mouth. The clinical efficacy of clozapine was more pronounced in participants resistant to typical neuroleptics in terms of clinical improvement (random effects OR 0.2 CI 0.1-0.5, NNT 5 CI 4-7) and symptom reduction. Thirty-two percent of treatment resistant people had a clinical improvement with clozapine treatment.

REVIEWER'S CONCLUSIONS

This systematic review confirms that clozapine is convincingly more effective than typical antipsychotic drugs in reducing symptoms of schizophrenia, producing clinically meaningful improvements and postponing relapse. Patients were more satisfied with clozapine treatment than with typical neuroleptic treatment. (ABSTRACT TRUNCATED

Double-blind study of clozapine dose response in chronic schizophrenia

OBJECTIVE

This study explored the relative efficacy of three different doses of clozapine.

METHOD

Fifty patients who met Kane et al.'s criteria for treatment-refractory schizophrenia or schizoaffective disorder were studied. All subjects were randomly assigned to 100, 300, or 600 mg/day of clozapine for 16 weeks of double-blind treatment. Forty-eight patients completed this first 16 weeks. Of the 50 patients, 36 went on to second and third 16-week trials of double-blind treatment at the remaining doses.

RESULTS

Four subjects (8%) responded to the first 16-week condition, and one subject (2%) responded to the next 16-week crossover condition. A chi-square comparison of the response rates from the three dose groups failed to show a significant effect. An analysis of variance (ANOVA) comparison of Brief Psychiatric Rating Scale-Anchored (BPRS-A) total change scores from baseline to last observation carried forward showed a significant dose effect (600>300>100 mg/day) at 16 weeks of treatment. A crossover ANOVA of the BPRS-A total scores from the 48-week study also showed that the main effect for dose was highly significant; the 100-mg/day dose gave the higher (poorer) values, and the 300- and 600-mg/ day doses gave equal (better) values. Gender played a role in clinical response to treatment at 100 mg/day.

CONCLUSIONS

Clozapine treatment at 100 mg/day was less effective than at 300 or 600 mg/day. At 100 mg/day, women responded better than did men. The 600 mg/day group had the best results, but an occasional patient required up to 900 mg/day. Overall response rates were lower than expected.

Toward a rational pharmacotherapy of comorbid substance abuse in schizophrenic patients

The prevalence of substance abuse is elevated among schizophrenic patients. When free of illicit substances and sober, substance-abusing schizophrenic patients may have a better prognosis than other frequently hospitalized schizophrenic patients. However, the cost of substance abuse is great in terms of rehospitalization, homelessness, risk of other medical illness, disruption of social and vocational function, exacerbation of symptoms, suicide, and increased health care expenses. Important recent developments in medications for reducing substance abuse in nonschizophrenic populations make it timely to consider factors that might contribute to substance abuse among schizophrenic patients. This review will focus on substances most frequently abused by schizophrenic patients: nicotine, alcohol, cannabis, and psychostimulants. It concentrates on two conceptual foci: "self-medication hypotheses" and "comorbid addiction vulnerability hypotheses". The relationship between these hypotheses and possible pharmacotherapeutic approaches for substance-abusing schizophrenic patients will be considered.