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Original Investigation |

Initial Severity of Schizophrenia and Efficacy of Antipsychotics Participant-Level Meta-analysis of 6 Placebo-Controlled Studies FREE

Toshi A. Furukawa, MD, PhD1,2; Stephen Z. Levine, PhD3; Shiro Tanaka, PhD4; Yair Goldberg, PhD5; Myrto Samara, MD6; John M. Davis, MD7; Andrea Cipriani, MD, PhD8,9; Stefan Leucht, MD6,9,10
[+] Author Affiliations
1Department of Health Promotion and Human Behavior, School of Public Health, Kyoto University Graduate School of Medicine, Kyoto, Japan
2Department of Clinical Epidemiology, School of Public Health, Kyoto University Graduate School of Medicine, Kyoto, Japan
3Department of Community Mental Health, University of Haifa, Haifa, Israel
4Department of Pharmacoepidemiology, School of Public Health, Kyoto University Graduate School of Medicine, Kyoto, Japan
5Department of Statistics, University of Haifa, Haifa, Israel
6Department of Psychiatry and Psychotherapy, Technische Universität München, München, Germany
7Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, Chicago
8World Health Organization Collaborating Centre for Research and Training in Mental Health and Service Evaluation, Department of Public Health and Community Medicine, Section of Psychiatry, University of Verona, Verona, Italy
9Department of Psychiatry, University of Oxford, Oxford, United Kingdom
10Institute of Psychiatry, King’s College London, London, United Kingdom
JAMA Psychiatry. 2015;72(1):14-21. doi:10.1001/jamapsychiatry.2014.2127.
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Published online

Importance  Antipsychotic drugs constitute the mainstay in the treatment of schizophrenia, and their efficacy is well established in hundreds of randomized clinical trials. However, it is not known whether they are effective or how effective they are across the wide range of baseline symptom severity.

Objective  To examine the influence of baseline severity of schizophrenia on the efficacy of antipsychotic drugs.

Design, Setting, and Participants  Meta-analysis of participant-level data from 3 pivotal randomized trials of acute schizophrenia (n = 611) and 3 pivotal trials in patients with predominantly negative symptoms of schizophrenia (n = 475).

Interventions  Olanzapine or risperidone vs placebo, and amisulpride vs placebo.

Main Outcomes and Measures  Change scores on the Positive and Negative Syndrome Scale (PANSS; score range, 30-210) and the Scale for the Assessment of Negative Symptoms (SANS; score range, 0-125) up to 6 weeks after baseline. The relationship between baseline and change scores for the drug and placebo groups was examined with 8 competing mixed-effects models for repeated measures.

Results  The best-fitting models showed that, for both types of patients, the interactions between baseline symptom severity and treatment were statistically significant (P < .01). The greater the baseline severity was, the greater the magnitude of the differences was between active treatment and placebo. In acute treatment, the mean differences in PANSS change scores were 9.5 points for patients who were mildly ill at baseline (baseline PANSS score of 58), 13.7 for moderately ill patients (baseline PANSS score of 75), 18.8 for markedly ill patients (baseline PANSS score of 95), and 24.0 for severely ill patients (baseline PANSS score of 116). In treatment of predominantly negative symptoms, the mean differences in SANS change scores were 1.7 for those who were moderately ill (baseline SANS score of 55), 5.7 for markedly ill patients (baseline SANS score of 70), and 9.7 for severely ill patients (baseline SANS score of 85).

Conclusions and Relevance  We can expect benefits of antipsychotic drugs for the full spectrum of patients likely to be treated for acute schizophrenia and for highly symptomatic patients with predominantly negative symptoms. Toward the mildest end of the spectrum, clinicians need to be aware that patients benefit less in terms of symptom improvement but may experience full adverse effects of antipsychotics. Clinicians also need to be aware that in addition to the treatment of active symptoms, which was the focus of this study, antipsychotics have another important action, namely to prevent relapses among patients in remission.

Figures in this Article

Schizophrenia is one of the most debilitating and chronic mental disorders and ranks among the top 20 causes of disability worldwide.1 Antipsychotic drugs constitute the mainstay for its treatment, and their efficacy is established beyond question in hundreds of randomized clinical trials (RCTs).2 Their worldwide annual sale is expected to reach $14.8 billion in 2014.3

The efficacy of another major class of psychotropic agents, antidepressants, in the treatment of depressive disorders has recently been called into question. Some studies have suggested that they may have less efficacy for the milder spectrum of the disorder,46 while others did not find such diminishing efficacy with lower baseline severity of depression.7,8 Earlier studies examining the relationship between average study-level initial severity and treatment response,5,7,9 however, are limited in statistical power to detect possible effects and are also subject to the ecological fallacy that relationships observed at the group level may not reflect the true relationships at the individual level.10,11

Patient-level data are therefore necessary to examine patient-level effect modifiers. The first participant-level meta-analysis examining this question pooled individual-level data from 6 RCTs (718 patients) comparing paroxetine or imipramine vs placebo in the acute treatment of major and minor depressive disorder and concluded that the substantial benefits of medications were seen only for patients with very severe depression.6 Subsequently, however, a much larger individual-level meta-analysis of 37 trials (8477 patients) examining 2 newer-generation antidepressants, fluoxetine hydrochloride and venlafaxine hydrochloride, found no effect of baseline severity on treatment efficacy.8

To our knowledge, the influence of baseline severity of schizophrenia on the efficacy of antipsychotic drugs has yet to be adequately examined. In this study, we carried out 2 separate participant-level meta-analyses of 3 RCTs comparing olanzapine and risperidone with placebo in the treatment of acute schizophrenia and 3 RCTs comparing amisulpride with placebo in the treatment of predominantly negative symptoms to examine the relationship between baseline symptom severity and efficacy of antipsychotics over placebo.

Included RCTs

We conducted a comprehensive systematic review of 15 major antipsychotic drugs and identified 97 placebo-controlled trials.2 Of these, we had access to participant-level data from 6 RCTs without any influence on the design, conduct, or reporting of the data analyses.

Three studies were pivotal RCTs comparing olanzapine or risperidone against placebo in the acute treatment of schizophrenia. The 2 olanzapine RCTs constitute all the placebo-controlled trials for the US Food and Drug Administration registration of the compound.12,13 The RCT comparing risperidone with placebo is its pivotal registration study.14,15 Three other studies represent all RCTs that examined amisulpride against placebo in the treatment of schizophrenia with predominantly negative symptoms to obtain market approval for this indication.1618 All the data were completely anonymized before we had access to them.

Of all the treatment arms in the RCTs, we only included the arms that used dosages indicated in the US Food and Drug Administration labels or the British National Formulary, ie, 10 to 30 mg/d for olanzapine, 4 to 16 mg/d for risperidone, and 50 to 300 mg/d for amisulpride. All the included arms were fixed-dose arms; in all but 1 trial, the fixed dose was administered immediately after randomization; in the other study,14,15 the dosage was titrated up to the maintenance dosage within 3 to 7 days. We excluded fixed-dose arms with olanzapine less than 10 mg/d (one 1-mg/d arm13 and one mean [range] 5 [2.5-7.5]–mg/d arm12) and one 2-mg/d risperidone arm14,15 because in such arms all patients take very low doses that are not effective for many of them,2 although such very low doses may be effective in individual patients. The optimal dosage of amisulpride for individuals in whom the negative symptoms of schizophrenia are predominant is 50 to 300 mg/d.19

Statistical Analyses

Our primary statistical analysis investigated the relationship between baseline symptom severity and subsequent symptom change in the comparisons of antipsychotics vs placebo. We conducted 2 separate analyses in patients with acute schizophrenia and in patients with predominantly negative symptoms to elucidate whether potential effects of baseline severity are restricted to one of these groups or are a more general phenomenon.

Among the acute studies, 1 trial of olanzapine12 used the Brief Psychiatric Rating Scale (BPRS),20 while the other trial of olanzapine13 and the trial of risperidone15 used the Positive and Negative Syndrome Scale (PANSS)21 to measure global symptom severity. To have the same outcome measure across all trials and to perform the meta-analysis on the same scale, we converted the BPRS scores into PANSS scores using an established algorithm; the correlation coefficient between BPRS total scores and PANSS total scores has been reported to range between 0.93 and 0.96.22 All items on the PANSS were recalibrated, where necessary, to be rated between 1 and 7 so that the possible score ranged from 30 to 210. All 3 amisulpride studies of predominantly negative symptoms of schizophrenia used the Scale for the Assessment of Negative Symptoms (SANS)23 as their primary outcome measure. The SANS has 30 items, each rated between 0 and 5, of which 25 items contribute to the total score. Thus, the possible score ranged from 0 to 125.

We followed the interpretive guides for the raw scores of the PANSS and SANS as established using the anchor-based approach linking these scores with the Clinical Global Impressions ratings: severity ratings of mildly ill, moderately ill, markedly ill, and severely ill corresponded with respective scores of 58, 75, 95, and 116 on the PANSS24 and 40, 55, 70, and 85 on the SANS.25

We conducted a participant-level meta-analysis to examine the relationship between baseline symptom severity and the differences in change scores between the drugs and placebo using a 3-level mixed-effects model repeated-measures analysis (MMRM) with maximum likelihood estimation.8,26 The levels accounted for the data structure such that level 1 represented time, level 2 the participant, and level 3 the trial. The following competing models with increasing complexity were tested: model 1, time, treatment, and the 2-way time × treatment interaction; model 2, model 1 plus baseline symptom score and all 2-way interactions among time, treatment, and baseline score; model 3, model 2 plus the 3-way interaction of linear time × treatment × baseline score; and model 4, model 3 plus the 2-way and 3-way interactions among quadratic time, treatment, and baseline score. These models were tested unadjusted and adjusted for confounders (age, sex, and duration of illness for patients with acute schizophrenia; age and sex for patients with predominantly negative symptoms). The model with the smallest Bayesian information criterion was chosen as the most parsimonious.27 We reported 6-week results based on the best-fitting models because it was the maximum duration for some of the included trials and therefore we were able to perform an analysis that accounted for follow-up time differences across studies. All statistical analyses were done in R statistical software version 3.1.028 using the nlme package version 3.1-117 (R Foundation for Statistical Computing).29

Sensitivity Analyses

Three sensitivity analyses of change from baseline using MMRM were conducted in our analysis of acutely ill patients, each comparing the 8 models as specified earlier. To check the consistency of our primary analysis using the PANSS, we carried out a sensitivity analysis using the BPRS instead of the PANSS. To examine whether the overall results observed with the total score also held for the positive and/or negative symptoms separately, we ran the same analyses for the positive and negative symptoms in the acute treatment of schizophrenia (eAppendix in the Supplement).

Characteristics of the Included RCTs

Table 1 shows the main characteristics of the included studies. The analysis of acute schizophrenia included a total of 611 inpatients diagnosed with the DSM-III-R, and the analysis of schizophrenia with predominantly negative symptoms included 475 such outpatients and inpatients diagnosed with the DSM-III or DSM-III-R.

Table Graphic Jump LocationTable 1.  Characteristics of the Included Studies
Baseline Severity and Symptom Change in the Acute Treatment of Schizophrenia

The best-fitting MMRM model to predict PANSS score change in the acute treatment of schizophrenia was model 2 (eTable 1 in the Supplement). In this model, the baseline PANSS score by treatment interaction was statistically significant (P = .004). Figure 1 shows a scatterplot of all observed scores, superimposed with regression lines for the antipsychotic and placebo arms at 6 weeks. The magnitude of the difference in PANSS change scores between the treatments increased with baseline PANSS score. The mean score difference between antipsychotics and placebo at 6 weeks was estimated to be 9.5 points for patients who were mildly ill at baseline (baseline PANSS score of 58), 13.7 points for patients who were moderately ill (baseline PANSS score of 75), 18.8 for markedly ill patients (baseline PANSS score of 95), and 24.0 for severely ill patients (baseline PANSS score of 116).

Place holder to copy figure label and caption
Figure 1.
Observed and Estimated Changes in the Positive and Negative Syndrome Scale (PANSS) Score Following 6-Week Acute Treatment of Schizophrenia

Lines indicate the expected reduction in PANSS score with placebo (black line) or drug (olanzapine or risperidone; blue line) at 6 weeks corresponding to the baseline score.

Graphic Jump Location
Baseline Severity and Symptom Change in the Treatment of Schizophrenia With Predominantly Negative Symptoms

The best-fitting model to predict SANS score change in the treatment of schizophrenia with predominantly negative symptoms was model 4, which contained linear and quadratic times and baseline SANS score without adjustment for sex or age (eTable 2 in the Supplement). We found that 3-way interactions of treatment × baseline SANS score × time, for both the quadratic and linear terms of time, were statistically significant (P = .02 and P = .004, respectively). This signifies that how the difference between treatments depended on the baseline SANS score over time was not simply linear but that a quadratic (ie, curvature) model improved the model fit to the data.

At 6 weeks, the 2 regression lines converged toward baseline SANS score around 50 and the difference between treatment and placebo increased with increasing baseline SANS score. The mean score difference between antipsychotics and placebo at 6 weeks was estimated to be 1.7 for patients who were moderately ill (baseline SANS score of 55), 5.7 for markedly ill patients (baseline SANS score of 70), and 9.7 for severely ill patients (baseline SANS score of 85).

Sensitivity Analyses

The sensitivity analyses using the BPRS total score instead of the PANSS, BPRS positive subscale, and BPRS negative subscale scores in the 2 olanzapine and risperidone studies revealed similar trends. The same model as in the primary analysis was replicated to best fit the data based on the Bayesian information criterion, and the interaction between baseline severity and treatment was statistically significant in all instances (BPRS total score, P = .008; BPRS positive subscale, P = .003; and BPRS negative subscale, P = .03), with the greater between-treatment differences for the patients with more severe illness (eTables 3-5 in the Supplement).

Analyzing the individual-level data from 3 pivotal trials of olanzapine and risperidone in the acute treatment of schizophrenia and 3 pivotal trials of amisulpride in the treatment of schizophrenia with predominantly negative symptoms, we found that the difference in symptom reduction between antipsychotics and placebo increased as the baseline severity increased. This effect was replicated for global as well as positive and negative symptoms in acute schizophrenia and for negative symptoms in predominantly negative schizophrenia.

Clinical Interpretations of the Findings

Many studies have examined possible predictors of change on antipsychotic drugs among patients with schizophrenia, including their initial symptom severity. Some studies have reported the association,31,32 but overall the results have been inconsistent, possibly owing to small sample sizes and/or methodological limitations.33 Moreover, these studies were interested in baseline severity merely as a predictor and none of them addressed its clinical implication for patient subgroups with different baseline severity (eg, mildly ill, moderately ill, and severely ill).

This problem was addressed in our study with the statistically appropriate and powerful method using individual-level data from multiple clinical trials and MMRM. We found that the 2 regression lines depicting the relationships between baseline severity and changes in severity grew apart as the baseline severity increased in both patients with acute schizophrenia and patients with predominantly negative symptoms. The baseline severity that is needed to have measurable treatment effects on antipsychotic drugs in comparison with placebo can be discussed from several points of view.

One approach is to calculate the between-group effect size. The standard deviations of change scores at 6 weeks for 3 severity groups with baseline PANSS scores up to 75, between 76 and 95, and greater than 95 were 20.0, 20.5, and 29.3, respectively. Dividing the expected mean differences by the corresponding standard deviation gives the expected effect sizes for the PANSS (Table 2). Because it has been commonly suggested that between-group effect sizes of 0.2, 0.5, and 0.8 would roughly correspond with small, medium, and large effects, respectively,34 one may say that the baseline PANSS scores must be around 40, 70, and 95 to have small, medium, and large between-group effect sizes, respectively, in the treatment of acute schizophrenia. In the treatment of patients with predominantly negative symptoms, the baseline SANS scores must be around 65 or 95 to have a small or medium effect, respectively (Table 3).

Table Graphic Jump LocationTable 2.  Baseline PANSS Scores and Expected Effect Sizes and NNT at 6 Weeks
Table Graphic Jump LocationTable 3.  Baseline SANS Scores and Expected Effect Sizes and NNT at 6 Weeks

Another approach is to calculate the number needed to treat (NNT) of achieving the minimally important change. The minimally important change is defined as the smallest change in score that the patient would perceive as beneficial and that would mandate, in the absence of adverse effects and excessive cost, a change in the patient’s health care.35,36 In the case of PANSS, the minimally important change has been established as approximately 15 points of absolute change using the anchor-based approach based on the Clinical Global Impressions improvement scores.24,37,38 By calculating the percentage of patients showing changes of 15 or more points in the drug and placebo arms using a validated formula,39,40 an NNT of 20 can be expected for patients with a baseline PANSS score around 40, an NNT of 10 for those with a baseline PANSS score around 55, and an NNT of 5 for those with a baseline PANSS score around 75 (Table 2). In the case of amisulpride studies, the corresponding NNTs would be 20 and 10 for patients with baseline SANS scores around 58 and 65, respectively (Table 3).

The treatment threshold would naturally differ from patient to patient and from treatment setting to treatment setting; indeed, Figure 1 and Figure 2 depict great variability in patient responses. However, on average, for patients scoring higher than 55 on the PANSS in the acute episode or 65 on the SANS when negative symptoms predominate, we may expect reasonable beneficial balance between benefits and risks of antipsychotic treatment. Below these thresholds, there may be more of a trade-off between benefits and risks: mildly ill patients benefit less in terms of effectiveness but still experience full adverse effects of antipsychotics.

Place holder to copy figure label and caption
Figure 2.
Observed and Estimated Changes in Scale for the Assessment of Negative Symptoms (SANS) Score Following 6-Week Treatment of Schizophrenia With Predominantly Negative Symptoms

Lines indicate the expected reduction in SANS score with placebo (black line) or drug (amisulpride; blue line) at 6 weeks corresponding to the baseline score.

Graphic Jump Location
Baseline Severity as Effect Modifier

Several explanations have been advanced for the observed interaction between baseline severity and change. The so-called law of initial value41 is sometimes cited to explain the influence of baseline severity. It states that the higher the initial value is, the greater the organism’s response is; it would therefore explain the greater symptom reductions among the more severely ill patients but cannot explain the difference in them between treatment and placebo.

Regression to the mean may have influenced the results. Generally, regression to the mean may be an analytic obstacle. This is especially true when allocation to treatment groups is nonrandom. However, its effect is minimized by randomization allocation, and it has an equal effect on both treatment and placebo groups.42,43 In the current RCT data, it cannot explain the differences in change between drug and placebo groups.

The greater reduction among the patients with initially severer illness who receive antipsychotics may be due to greater leeway for improvement among such people when antipsychotics are effective, while the same did not seem to apply to those taking placebo. If there are few symptoms at baseline, there is also little room for improvement compared with placebo. As an analogy from internal medicine, fewer patients with hypercholesterolemia die of cardiovascular events within a year when the baseline risk is low than when it is high, and therefore the absolute benefit derived from lowering the cholesterol level is accordingly lower among the former than among the latter.44

Symptom Treatment and Episode Prophylaxis

All the studies included in our analyses aimed to reduce symptoms of schizophrenia, either positive or negative. Antipsychotics are used for another very important action, ie, to prevent relapses.45 Our findings regarding baseline severity on symptom reduction therefore do not inform the influence of baseline severity on the prophylactic effectiveness of antipsychotics. We would need participant-level data from long-term maintenance trials of antipsychotics to address this question.

Limitations and Implications

Our study is not without weaknesses. First, we did not have many mildly ill patients or any borderline ill patients. The baseline severity of the included patients ranged from scores between 49 and 158 on the PANSS and between 60 and 125 on the SANS; the obtained relationships should be valid for baseline scores in and around that range, but our regression lines may be unstable toward the lowest end of baseline severity. We therefore should not place too much confidence in the crossing values but rather should focus on the implications of the strong interaction that we observed. Second, although we included trials of olanzapine, risperidone, and amisulpride, the findings need be replicated with other placebo-controlled trials involving other antipsychotics as well. However, the availability of individual-level data in this study was apparently not dependent on the observed relationship between baseline severity and decline in symptoms, and we remain unsure whether the possible availability bias worked toward overestimating or underestimating our primary outcome. It is also notable that we observed a significant influence of baseline symptom severity in the 2 separate but parallel analyses with different populations (acute schizophrenia and schizophrenia with predominantly negative symptoms) using different medications (risperidone/olanzapine and amisulpride) and different outcome measures (PANSS and SANS).

The clinical implications of our findings may be as follows: we can expect benefits of antipsychotics for patients with the full spectrum of severity who we are likely to treat for acute schizophrenia and for highly symptomatic patients with predominantly negative symptoms, and the severer the illness is at baseline, the bigger the benefits will be. Only toward the mildest end of the spectrum, there may be trade-offs between benefits and risks of the short-term acute treatment, and the clinician needs to confirm the patient’s diagnosis and start treatment judiciously, probably with low doses of antipsychotics with fewer adverse effects.

There are 3 main research implications. First, our study has provided another example of fruitful data sharing especially with regard to examination of possible effect modifiers. Such participant-level analyses should be further encouraged, and efforts need be expended to remove ethical and logistical barriers to such collaboration. Second, in conducting placebo-controlled trials of antipsychotics, our results suggest that trials would be more likely to detect signals if they were to concentrate on patients with severer illness. The current practice of setting this threshold to a score of 75 on the PANSS may be justifiable to strike a balance between patient recruitment and signal detection; if there is less difficulty in patient recruitment, the threshold could be higher. Third, the questions remain as to why we often but not always observe an influence of baseline severity on symptom reduction in depression and schizophrenia and whether we observe similar relationships in anxiety, insomnia, and other psychiatric disorders and in treatment of general medical diseases. Further empirical studies are needed to shed light on the mechanisms involved and to inform the clinical practice and research methods.

We can expect benefits of antipsychotic drugs for the full spectrum of patients we are likely to treat for acute schizophrenia and for highly symptomatic patients with predominantly negative symptoms. Toward the mildest end of the spectrum, judicious clinical consideration of trade-offs between benefits and risks of the antipsychotic treatment is required.

Corresponding Author: Toshi A. Furukawa, MD, PhD, Departments of Health Promotion and Human Behavior and of Clinical Epidemiology, School of Public Health, Kyoto University Graduate School of Medicine, Yoshida Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan (furukawa@kuhp.kyoto-u.ac.jp).

Submitted for Publication: February 17, 2014; final revision received July 17, 2014; accepted July 24, 2014.

Published Online: November 5, 2014. doi:10.1001/jamapsychiatry.2014.2127.

Author Contributions: Drs Furukawa and Levine are joint first authors. Dr Leucht had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Furukawa, Leucht.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Furukawa, Levine, Leucht.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Furukawa, Levine, Tanaka, Goldberg, Leucht.

Administrative, technical, or material support: Samara.

Study supervision: Furukawa, Leucht.

Conflict of Interest Disclosures: Dr Furukawa reported having received lecture fees from Eli Lilly and Co, Meiji, Mochida, MSD, Pfizer, and Tanabe-Mitsubishi, consultancy fees from Sekisui and Takeda Science Foundation, royalties from Igaku-Shoin, Seiwa-Shoten, and Nihon Bunka Kagaku-sha, and research project funding from the Japanese Ministry of Education, Science, and Technology, the Japanese Ministry of Health, Labor, and Welfare, and the Japan Foundation for Neuroscience and Mental Health, and he is a diplomate of the Academy of Cognitive Therapy. Dr Levine reported having received research support, consultancy fees, and/or travel support from Shire, F. Hoffmann–La Roche, and Eli Lilly and Co. Dr Leucht reported having received honoraria for lectures from Abbvie, AstraZeneca, Bristol-Myers Squibb, ICON, Eli Lilly and Co, Janssen, Johnson & Johnson, Roche, Sanofi-Aventis, Lundbeck, and Pfizer and for consulting or advisory boards from Roche, Eli Lilly and Co, MedAvante, Bristol-Myers Squibb, Alkermes, Janssen, Johnson & Johnson, and Lundbeck, and Eli Lilly and Co has provided medication for a study with him as primary investigator. No other disclosures were reported.

Funding/Support: Eli Lilly and Co, Janssen Pharmaceuticals Inc, and Sanofi-Aventis allowed use of their participant-level data.

Role of the Funder/Sponsor: Eli Lilly and Co, Janssen Pharmaceuticals Inc, and Sanofi-Aventis had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

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PubMed   |  Link to Article
Andreasen  NC. Scale for the Assessment of Negative Symptoms (SANS). Iowa City: University of Iowa; 1983.
Leucht  S, Kane  JM, Kissling  W, Hamann  J, Etschel  E, Engel  RR.  What does the PANSS mean? Schizophr Res. 2005;79(2-3):231-238.
PubMed   |  Link to Article
Levine  SZ, Leucht  S.  Identifying clinically meaningful symptom response cut-off values on the SANS in predominant negative symptoms. Schizophr Res. 2013;145(1-3):125-127.
PubMed   |  Link to Article
Hedeker  D, Gibbons  RD. Longitudinal Data Analysis. Hoboken, NJ: John Wiley & Sons; 2006.
Schwarz  G.  Estimating the dimension of a model. Ann Stat. 1978;6(2):461-464.
Link to Article
Ihaka  R, Gentleman  R.  R: a language for data analysis and graphics. J Comput Graph Stat. 1996;5(3):299-314.
Pinheiro  J, Bates  D, DebRoy  S, Sarkar  D; R Core Team. nlme: Linear and Nonlinear Mixed Effects Models: R Package Version 3.1-117. Vienna, Austria: R Foundation for Statistical Computing; 2014.
Andreasen  NC, Olsen  S.  Negative v positive schizophrenia: definition and validation. Arch Gen Psychiatry. 1982;39(7):789-794.
PubMed   |  Link to Article
Stern  RG, Kahn  RS, Davidson  M.  Predictors of response to neuroleptic treatment in schizophrenia. Psychiatr Clin North Am. 1993;16(2):313-338.
PubMed
Rabinowitz  J, Werbeloff  N, Caers  I,  et al.  Determinants of antipsychotic response in schizophrenia: implications for practice and future clinical trials. J Clin Psychiatry. 2014;75(4):e308-e316.
PubMed   |  Link to Article
Awad  AG, Gaebel  W. Prediction of Neuroleptic Treatment Outcome in Schizophrenia: Concepts and Methods. New York, NY: Springer-Verlag; 1994.
Cohen  J. Statistical Power Analysis in the Behavioral Sciences. Hillsdale, NJ: Erlbaum; 1988.
Jaeschke  R, Singer  J, Guyatt  GH.  Measurement of health status: ascertaining the minimal clinically important difference. Control Clin Trials. 1989;10(4):407-415.
PubMed   |  Link to Article
Furukawa  TA, Jaeschke  R, Cook  D, Guyatt  G. Measurement of patients' experience. In: Guyatt  G, Drummond  R, Meade  MO, Cook  DJ, eds. Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice.2nd ed. New York, NY: McGraw-Hill; 2008:249-271.
Hermes  ED, Sokoloff  D, Stroup  TS, Rosenheck  RA.  Minimum clinically important difference in the Positive and Negative Syndrome Scale with data from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE). J Clin Psychiatry. 2012;73(4):526-532.
PubMed   |  Link to Article
Leucht  S, Kane  JM, Etschel  E, Kissling  W, Hamann  J, Engel  RR.  Linking the PANSS, BPRS, and CGI: clinical implications. Neuropsychopharmacology. 2006;31(10):2318-2325.
PubMed
da Costa  BR, Rutjes  AW, Johnston  BC,  et al.  Methods to convert continuous outcomes into odds ratios of treatment response and numbers needed to treat: meta-epidemiological study. Int J Epidemiol. 2012;41(5):1445-1459.
PubMed   |  Link to Article
Furukawa  TA, Cipriani  A, Barbui  C, Brambilla  P, Watanabe  N.  Imputing response rates from means and standard deviations in meta-analyses. Int Clin Psychopharmacol. 2005;20(1):49-52.
PubMed   |  Link to Article
Wilder  J.  The law of initial value in neurology and psychiatry: facts and problems. J Nerv Ment Dis. 1957;125(1):73-86.
PubMed   |  Link to Article
Campbell  DT, Kenny  DA. A Primer on Regression Artifacts. New York, NY: Guilford Press; 2002.
Barnett  AG, van der Pols  JC, Dobson  AJ.  Regression to the mean: what it is and how to deal with it. Int J Epidemiol. 2005;34(1):215-220.
PubMed   |  Link to Article
Baigent  C, Keech  A, Kearney  PM,  et al; Cholesterol Treatment Trialists’ (CTT) Collaborators.  Efficacy and safety of cholesterol-lowering treatment: prospective meta-analysis of data from 90,056 participants in 14 randomised trials of statins. Lancet. 2005;366(9493):1267-1278.
PubMed   |  Link to Article
Leucht  S, Tardy  M, Komossa  K,  et al.  Antipsychotic drugs versus placebo for relapse prevention in schizophrenia: a systematic review and meta-analysis. Lancet. 2012;379(9831):2063-2071.
PubMed   |  Link to Article

Figures

Place holder to copy figure label and caption
Figure 1.
Observed and Estimated Changes in the Positive and Negative Syndrome Scale (PANSS) Score Following 6-Week Acute Treatment of Schizophrenia

Lines indicate the expected reduction in PANSS score with placebo (black line) or drug (olanzapine or risperidone; blue line) at 6 weeks corresponding to the baseline score.

Graphic Jump Location
Place holder to copy figure label and caption
Figure 2.
Observed and Estimated Changes in Scale for the Assessment of Negative Symptoms (SANS) Score Following 6-Week Treatment of Schizophrenia With Predominantly Negative Symptoms

Lines indicate the expected reduction in SANS score with placebo (black line) or drug (amisulpride; blue line) at 6 weeks corresponding to the baseline score.

Graphic Jump Location

Tables

Table Graphic Jump LocationTable 1.  Characteristics of the Included Studies
Table Graphic Jump LocationTable 2.  Baseline PANSS Scores and Expected Effect Sizes and NNT at 6 Weeks
Table Graphic Jump LocationTable 3.  Baseline SANS Scores and Expected Effect Sizes and NNT at 6 Weeks

References

Vos  T, Flaxman  AD, Naghavi  M,  et al.  Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012;380(9859):2163-2196.
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Leucht  S, Cipriani  A, Spineli  L,  et al.  Comparative efficacy and tolerability of 15 antipsychotic drugs in schizophrenia: a multiple-treatments meta-analysis. Lancet. 2013;382(9896):951-962.
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Research  BCC. Antipsychotic drugs: technologies and global markets. http://www.bccresearch.com/market-research/pharmaceuticals/antipsychotic-drugs-markets-phm063a.html. Accessed January 4, 2014.
Khan  A, Brodhead  AE, Kolts  RL, Brown  WA.  Severity of depressive symptoms and response to antidepressants and placebo in antidepressant trials. J Psychiatr Res. 2005;39(2):145-150.
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Kirsch  I, Deacon  BJ, Huedo-Medina  TB, Scoboria  A, Moore  TJ, Johnson  BT.  Initial severity and antidepressant benefits: a meta-analysis of data submitted to the Food and Drug Administration. PLoS Med. 2008;5(2):e45.
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Fournier  JC, DeRubeis  RJ, Hollon  SD,  et al.  Antidepressant drug effects and depression severity: a patient-level meta-analysis. JAMA. 2010;303(1):47-53.
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Melander  H, Salmonson  T, Abadie  E, van Zwieten-Boot  B.  A regulatory apologia: a review of placebo-controlled studies in regulatory submissions of new-generation antidepressants. Eur Neuropsychopharmacol. 2008;18(9):623-627.
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Gibbons  RD, Hur  K, Brown  CH, Davis  JM, Mann  JJ.  Benefits from antidepressants: synthesis of 6-week patient-level outcomes from double-blind placebo-controlled randomized trials of fluoxetine and venlafaxine. Arch Gen Psychiatry. 2012;69(6):572-579.
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Khan  A, Leventhal  RM, Khan  SR, Brown  WA.  Severity of depression and response to antidepressants and placebo: an analysis of the Food and Drug Administration database. J Clin Psychopharmacol. 2002;22(1):40-45.
PubMed   |  Link to Article
Simmonds  MC, Higgins  JP.  Covariate heterogeneity in meta-analysis: criteria for deciding between meta-regression and individual patient data. Stat Med. 2007;26(15):2982-2999.
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Riley  RD, Lambert  PC, Staessen  JA,  et al.  Meta-analysis of continuous outcomes combining individual patient data and aggregate data. Stat Med. 2008;27(11):1870-1893.
PubMed   |  Link to Article
Beasley  CM  Jr, Tollefson  G, Tran  P, Satterlee  W, Sanger  T, Hamilton  S.  Olanzapine versus placebo and haloperidol: acute phase results of the North American double-blind olanzapine trial. Neuropsychopharmacology. 1996;14(2):111-123.
PubMed   |  Link to Article
Beasley  CM  Jr, Sanger  T, Satterlee  W, Tollefson  G, Tran  P, Hamilton  S.  Olanzapine versus placebo: results of a double-blind, fixed-dose olanzapine trial. Psychopharmacology (Berl). 1996;124(1-2):159-167.
PubMed   |  Link to Article
Chouinard  G, Jones  B, Remington  G,  et al.  A Canadian multicenter placebo-controlled study of fixed doses of risperidone and haloperidol in the treatment of chronic schizophrenic patients. J Clin Psychopharmacol. 1993;13(1):25-40.
PubMed
Marder  SR, Meibach  RC.  Risperidone in the treatment of schizophrenia. Am J Psychiatry. 1994;151(6):825-835.
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Loo  H, Poirier-Littre  MF, Theron  M, Rein  W, Fleurot  O.  Amisulpride versus placebo in the medium-term treatment of the negative symptoms of schizophrenia. Br J Psychiatry. 1997;170:18-22.
PubMed   |  Link to Article
Danion  JM, Rein  W, Fleurot  O; Amisulpride Study Group.  Improvement of schizophrenic patients with primary negative symptoms treated with amisulpride. Am J Psychiatry. 1999;156(4):610-616.
PubMed
Boyer  P, Lecrubier  Y, Puech  AJ, Dewailly  J, Aubin  F.  Treatment of negative symptoms in schizophrenia with amisulpride. Br J Psychiatry. 1995;166(1):68-72.
PubMed   |  Link to Article
Leucht  S, Pitschel-Walz  G, Engel  RR, Kissling  W.  Amisulpride, an unusual “atypical” antipsychotic: a meta-analysis of randomized controlled trials. Am J Psychiatry. 2002;159(2):180-190.
PubMed   |  Link to Article
Overall  JE, Gorham  DR.  The Brief Psychiatric Rating Scale. Psychol Rep. 1962;10:799-812.
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Kay  SR, Fiszbein  A, Opler  LA.  The Positive and Negative Syndrome Scale (PANSS) for schizophrenia. Schizophr Bull. 1987;13(2):261-276.
PubMed   |  Link to Article
Leucht  S, Rothe  P, Davis  JM, Engel  RR.  Equipercentile linking of the BPRS and the PANSS. Eur Neuropsychopharmacol. 2013;23(8):956-959.
PubMed   |  Link to Article
Andreasen  NC. Scale for the Assessment of Negative Symptoms (SANS). Iowa City: University of Iowa; 1983.
Leucht  S, Kane  JM, Kissling  W, Hamann  J, Etschel  E, Engel  RR.  What does the PANSS mean? Schizophr Res. 2005;79(2-3):231-238.
PubMed   |  Link to Article
Levine  SZ, Leucht  S.  Identifying clinically meaningful symptom response cut-off values on the SANS in predominant negative symptoms. Schizophr Res. 2013;145(1-3):125-127.
PubMed   |  Link to Article
Hedeker  D, Gibbons  RD. Longitudinal Data Analysis. Hoboken, NJ: John Wiley & Sons; 2006.
Schwarz  G.  Estimating the dimension of a model. Ann Stat. 1978;6(2):461-464.
Link to Article
Ihaka  R, Gentleman  R.  R: a language for data analysis and graphics. J Comput Graph Stat. 1996;5(3):299-314.
Pinheiro  J, Bates  D, DebRoy  S, Sarkar  D; R Core Team. nlme: Linear and Nonlinear Mixed Effects Models: R Package Version 3.1-117. Vienna, Austria: R Foundation for Statistical Computing; 2014.
Andreasen  NC, Olsen  S.  Negative v positive schizophrenia: definition and validation. Arch Gen Psychiatry. 1982;39(7):789-794.
PubMed   |  Link to Article
Stern  RG, Kahn  RS, Davidson  M.  Predictors of response to neuroleptic treatment in schizophrenia. Psychiatr Clin North Am. 1993;16(2):313-338.
PubMed
Rabinowitz  J, Werbeloff  N, Caers  I,  et al.  Determinants of antipsychotic response in schizophrenia: implications for practice and future clinical trials. J Clin Psychiatry. 2014;75(4):e308-e316.
PubMed   |  Link to Article
Awad  AG, Gaebel  W. Prediction of Neuroleptic Treatment Outcome in Schizophrenia: Concepts and Methods. New York, NY: Springer-Verlag; 1994.
Cohen  J. Statistical Power Analysis in the Behavioral Sciences. Hillsdale, NJ: Erlbaum; 1988.
Jaeschke  R, Singer  J, Guyatt  GH.  Measurement of health status: ascertaining the minimal clinically important difference. Control Clin Trials. 1989;10(4):407-415.
PubMed   |  Link to Article
Furukawa  TA, Jaeschke  R, Cook  D, Guyatt  G. Measurement of patients' experience. In: Guyatt  G, Drummond  R, Meade  MO, Cook  DJ, eds. Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice.2nd ed. New York, NY: McGraw-Hill; 2008:249-271.
Hermes  ED, Sokoloff  D, Stroup  TS, Rosenheck  RA.  Minimum clinically important difference in the Positive and Negative Syndrome Scale with data from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE). J Clin Psychiatry. 2012;73(4):526-532.
PubMed   |  Link to Article
Leucht  S, Kane  JM, Etschel  E, Kissling  W, Hamann  J, Engel  RR.  Linking the PANSS, BPRS, and CGI: clinical implications. Neuropsychopharmacology. 2006;31(10):2318-2325.
PubMed
da Costa  BR, Rutjes  AW, Johnston  BC,  et al.  Methods to convert continuous outcomes into odds ratios of treatment response and numbers needed to treat: meta-epidemiological study. Int J Epidemiol. 2012;41(5):1445-1459.
PubMed   |  Link to Article
Furukawa  TA, Cipriani  A, Barbui  C, Brambilla  P, Watanabe  N.  Imputing response rates from means and standard deviations in meta-analyses. Int Clin Psychopharmacol. 2005;20(1):49-52.
PubMed   |  Link to Article
Wilder  J.  The law of initial value in neurology and psychiatry: facts and problems. J Nerv Ment Dis. 1957;125(1):73-86.
PubMed   |  Link to Article
Campbell  DT, Kenny  DA. A Primer on Regression Artifacts. New York, NY: Guilford Press; 2002.
Barnett  AG, van der Pols  JC, Dobson  AJ.  Regression to the mean: what it is and how to deal with it. Int J Epidemiol. 2005;34(1):215-220.
PubMed   |  Link to Article
Baigent  C, Keech  A, Kearney  PM,  et al; Cholesterol Treatment Trialists’ (CTT) Collaborators.  Efficacy and safety of cholesterol-lowering treatment: prospective meta-analysis of data from 90,056 participants in 14 randomised trials of statins. Lancet. 2005;366(9493):1267-1278.
PubMed   |  Link to Article
Leucht  S, Tardy  M, Komossa  K,  et al.  Antipsychotic drugs versus placebo for relapse prevention in schizophrenia: a systematic review and meta-analysis. Lancet. 2012;379(9831):2063-2071.
PubMed   |  Link to Article

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Multimedia

Supplement.

eAppendix. Details of the BPRS positive and negative subscales used in the sensitivity analyses

eReferences

eTable 1. MMRM analyses of the PANSS total

eTable 2. MMRM analyses of the SANS total

eTable 3. MMRM analyses of the BPRS total

eTable 4. MMRM analyses of the BPRS positive subscale

eTable 5. MMRM analyses of the BPRS negative subscale

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