Factors involved in the level of functioning of patients with schizophrenia according to latent variable modeling

Large-scale evaluation of the Positive and Negative Syndrome Scale (PANSS) symptom architecture in schizophrenia

Although the Positive and Negative Syndrome Scale (PANSS) is widely utilized in schizophrenia research, variability in specific item loading exist, hindering reproducibility and generalizability of findings across schizophrenia samples. We aim to establish a common PANSS factor structure from a large multi-ethnic sample and validate it against a meta-analysis of existing PANSS models. Schizophrenia participants (N = 3511) included in the current study were part of the Singapore Translational and Clinical Research Program (STCRP) and the Clinical Antipsychotic Trials for Intervention Effectiveness (CATIE). Exploratory Factor Analysis (EFA) was conducted to identify the factor structure of PANSS and validated with a meta-analysis (N = 16,171) of existing PANSS models. Temporal stability of the PANSS model and generalizability to individuals at ultra-high risk (UHR) of psychosis were evaluated. A five-factor solution best fit the PANSS data. These were the i) Positive, ii) Negative, iii) Cognitive/disorganization, iv) Depression/anxiety and v) Hostility factors. Convergence of PANSS symptom architecture between EFA model and meta-analysis was observed. Modest longitudinal reliability was observed. The schizophrenia derived PANSS factor model fit the UHR population, but not vice versa. We found that two other domains, Social Amotivation (SA) and Diminished Expression (DE), were nested within the negative symptoms factor. Here, we report one of the largest transethnic factorial structures of PANSS symptom domains (N = 19,682). Evidence reported here serves as crucial consolidation of a common PANSS structure that could aid in furthering our understanding of schizophrenia.

Modelling change in neurocognition, symptoms and functioning in young people with emerging mental disorders

Mental disorders and their functional impacts evolve dynamically over time. Neurocognition and clinical symptoms are commonly modelled as predictors of functioning, however, studies tend to rely on static variables and adult samples with chronic disorders, with limited research investigating change in these variables in young people with emerging mental disorders. These relationships were explored in a longitudinal clinical cohort of young people accessing early intervention mental health services in Australia, around three-quarters of whom presented with a mood disorder (N = 176, aged 12-30 at baseline). Bivariate latent change score models quantified associations between neurocognition (a latent variable of working memory, verbal memory, visuospatial memory, and cognitive flexibility), global clinical symptoms, and functioning (self- and clinician-rated) and their relative change over follow-up (median = 20 months). We found that longitudinal changes in functioning were coupled with changes in global clinical symptoms (β = -0.43, P < 0.001), such that improvement in functioning was related to improvement in clinical symptoms. Changes in neurocognition were not significantly associated with changes in functioning or clinical symptoms. Main findings were upheld in three sensitivity analyses restricting the sample to: (a) adults aged 18-30; (b) participants with 12-24 months of follow-up; and (c) participants without a psychotic disorder. Our findings show that global symptom reduction and functional improvement are related in young people with emerging mental disorders. More work is needed to determine the temporal precedence of change in these variables. Future studies should apply this methodology to intervention studies to untangle the causal dynamics between neurocognition, symptoms, and functioning.

Efficacy of lurasidone across five symptom dimensions of schizophrenia: Pooled analysis of short-term, placebo-controlled studies

Objective:

To evaluate the efficacy of lurasidone for schizophrenia using an established five-factor model of the Positive and Negative Syndrome Scale (PANSS).

Methods:

Patient-level data were pooled from five randomized, double-blind, placebo-controlled, 6-week studies of lurasidone (fixed doses, 40–160 mg/d) for patients with an acute exacerbation of schizophrenia. Changes in five established PANSS factors were assessed using mixed-model repeated measures analysis.

Results:

Compared with placebo (n = 496), lurasidone (n = 1029, dose groups pooled) significantly improved the PANSS total score at Week 6 (−22.6 vs. −12.8; P < 0.001; effect size, 0.45), as well as all factor scores (P < 0.001 for each): positive symptoms (−8.4 vs. −6.0; effect size, 0.43), negative symptoms (−5.2 vs. −3.3; effect size, 0.33), disorganized thought (−4.9 vs. −2.8; effect size, 0.42), hostility/excitement (−2.7 vs. −1.6; effect size, 0.31), and depression/anxiety (−3.2 vs. −2.3; effect size, 0.31). Separation from placebo occurred at Week 1 for the positive symptoms, disorganized thought, and hostility/excitement factors and at Week 2 for the other factors.

Conclusions:

In this pooled analysis of short-term studies in patients with acute schizophrenia, lurasidone demonstrated significant improvement for each of the five PANSS factor scores, indicating effectiveness across the spectrum of schizophrenia symptoms.

[Effect of Lurasidone on symptoms of schizophrenia in five-factor dimensional model: pooled analysis of two short-term, randomized, double-blind, placebo-controlled studies in patients from Russia and Ukraine]

AIM

Evaluation of a new five-factor dimensional model of schizophrenia in recent revisions of classifications of mental disorders (DSM-5 and ICD-11) dictates the need to use this approach in conducting a comprehensive assessment of the effectiveness of new antipsychotic agents, including ethnically homogeneous populations of patients.

MATERIAL AND METHODS

Post-hoc analysis of pooled data from two randomized, double-blind, placebo-controlled, 6-week clinical studies (RCTs) of lurasidone (fixed doses, 40, 80, 120 or 160 mg/d) in patients experiencing an acute exacerbation of schizophrenia. Changes in PANSS total score, CGI-S score and five established PANSS factors were assessed using mixed-model repeated measures analysis.

RESULTS

Lurasidone (n=162, dose groups pooled) compared with placebo (n=68), significantly improved the PANSS total score at Week 6 (-23.0 vs. -10.5; p<0.001; effect size 0.82) as well as all PANSS factor scores: positive symptoms (-8.5 vs. -4.2; p<0.001; effect size 0.88), negative symptoms (-4.4 vs. -2.8; p=0.011, effect size 0.44), disorganized thoughts (-4.4 vs. -2.1; p<0.001; effect size 0.70), hostility/excitement (-2.7 vs. -0.7; p<0.001; effect size 0.66), and depression/anxiety (-3.5 vs. -2.2; p=0.002; effect size 0.53).

CONCLUSION

Lurasidone demonstrated significant improvement for both PANSS total score and each of the five PANSS factor scores, indicating effectiveness across the broad spectrum of schizophrenia symptoms. Effect size for both PANSS total score and each of the five PANSS factor scores for the local population was higher than for the wider population, which included patients from various countries.

M. Staging of Schizophrenia With the Use of PANSS: An International Multi-Center Study

INTRODUCTION

A specific clinically relevant staging model for schizophrenia has not yet been developed. The aim of the current study was to evaluate the factor structure of the PANSS and develop such a staging method.

METHODS

Twenty-nine centers from 25 countries contributed 2358 patients aged 37.21 ± 11.87 years with schizophrenia. Analysis of covariance, Exploratory Factor Analysis, Discriminant Function Analysis, and inspection of resultant plots were performed.

RESULTS

Exploratory Factor Analysis returned 5 factors explaining 59% of the variance (positive, negative, excitement/hostility, depression/anxiety, and neurocognition). The staging model included 4 main stages with substages that were predominantly characterized by a single domain of symptoms (stage 1: positive; stages 2a and 2b: excitement/hostility; stage 3a and 3b: depression/anxiety; stage 4a and 4b: neurocognition). There were no differences between sexes. The Discriminant Function Analysis developed an algorithm that correctly classified >85% of patients.

DISCUSSION

This study elaborates a 5-factor solution and a clinical staging method for patients with schizophrenia. It is the largest study to address these issues among patients who are more likely to remain affiliated with mental health services for prolonged periods of time.

Resilience and recovery style: a retrospective study on associations among personal resources, symptoms, neurocognition, quality of life and psychosocial functioning in psychotic patients

Background: Personal resources have been identified as important factors in predicting patient healing or symptoms control in schizophrenia. This observational retrospective study aims to explore the influence of resilience and recovery style on the modalities of clinical presentation of the disease, as well as individual functioning and quality of life. Methods: Participants were patients affected by schizophrenia spectrum disorders assessed at different mental health facilities. The rating scales considered are the following: Resilience Scale 10-items (RS); Recovery Style Questionnaire (RSQ); Montreal Cognitive Assessment (MoCA); Schizophrenia Quality of Life Scale (SQLS); Life Skills Profile (LSP); Positive and Negative Syndrome Scale (PANSS). Results: Forty-four patients fulfilled the inclusion criteria. The mean age was 46 years; the average length of the history of the disease at recruitment was 23 years with an average age at first episode of psychosis (FEP) of 23 years. General psychopathology, neurocognition, and integration recovery style can predict psychosocial functioning and explain ~54% of the LSP variance; RS total score and PANSS general psychopathology score can predict and explain ~29% of the LSP variance. A negative association between PANSS general psychopathology and LSP total score supports the need to reduce first the symptomatology, and then successfully apply other types of interventions. A strong positive association between neurocognition and life functioning was detected, showing that deficits in neurocognition have proved to be important predictors of the functional outcome. Integration was also proven to be significantly associated with a good functional outcome. Psychotic symptoms turn out to be a negative predictive factor, whereas resilience can be hypothesized as a protective factor. Conclusions: Resilience and recovery style "integration" can be considered as two complementary predictive resources for a good outcome; this result supports the need to set up personalized treatments, based on the characteristics of the patients.

A systematic literature review identifying associations between outcomes and quality of life (QoL) or healthcare resource utilization (HCRU) in schizophrenia

AIMS

There have been no systematic literature reviews (SLRs) evaluating the identified association between outcomes (e.g. clinical, functional, adherence, societal burden) and Quality-of-Life (QoL) or Healthcare Resource Utilization (HCRU) in schizophrenia. The objective of this study was to conduct a SLR of published data on the relationship between outcomes and QoL or HCRU.

MATERIALS AND METHODS

Electronic searches were conducted in Embase and Medline, for articles which reported on the association between outcomes and QoL or HCRU. Inclusion and exclusion criteria were applied to identify the most relevant articles and studies and extract their data. A summary table was developed to illustrate the strength of associations, based on p-values and correlations.

RESULTS

One thousand and two abstracts were retrieved; five duplicates were excluded; 997 abstracts were screened and 95 references were retained for full-text screening. Thrirty-one references were included in the review. The most commonly used questionnaire, which also demonstrated the strongest associations (defined as a p < 0.0001 and/or correlation ±0.70), was the Positive and Negative Syndrome Scale (PANSS) associated with HCRU and QoL (the SF-36, the Schizophrenia Quality-of-Life questionnaire [S-QOL-18], the Quality-of-Life Scale [QLS]). Other robust correlations included the Clinical Global Impression-Severity (CGI-S) with QoL (EQ5D), relapse with HCRU, and remission with QoL (EQ5D). Lastly, functioning (Work Rehabilitation Questionnaire [WORQ] and Personal and Social Performance Scale [PSP]) was found to be associated to QoL (QLS and Subjective Well-being under Neuroleptics Questionnaire [SWN]).

LIMITATIONS

This study included data from an 11-year period, and other instruments less frequently used may be further investigated.

CONCLUSIONS

The evidence suggests that the PANSS is the clinical outcome that currently provides the most frequent and systematic associations with HCRU and QoL endpoints in schizophrenia.

A reassessment of the higher-order factor structure of the German Schizotypal Personality Questionnaire (SPQ-G) in German-speaking adults

The Schizotypal Personality Questionnaire (SPQ) is a widely-used self-report instrument for the assessment of schizotypal personality traits. However, the factor structure of scores on English and non-English translations of the SPQ has been a matter of debate. With little previous factorial evaluation of the German version of the SPQ (SPQ-G), we re-assessed the higher-order factor structure of the measure. A total of 2,428 German-speaking adults from Central Europe (CE) and the United Kingdom (UK) completed the SPQ-G. Confirmatory factor analysis - testing proposed 2-, 3-, and 4-factor models of SPQ-G scores - indicated that the 4-factor solution had best fit. Partial measurement invariance across cultural group (CE and UK) and sex was obtained for the 4-factor model. Further analyses showed CE participants had significantly higher scores than UK participants on one schizotypal facet. These results suggest that scores on the SPQ-G are best explained in terms of a higher-order, 4-factor solution in German migrant and non-migrant adults.

Functional remission in schizophrenia: A FROGS-based definition and its convergent validity

Functional remission concerns only one third of schizophrenia patients who achieved symptomatic remission. We previously developed a scale devoted to functional remission, named the FROGS (Functional Remission Of General Schizophrenia). This instrument encompasses three clinically relevant dimensions. The aim of this study is to provide a threshold for functional remission relying on these three dimensions, and to compare its psychometric properties with other scales devoted to functional remission. We tested the characteristics of functional remission according to the FROGS. The FROGS was used in different European countries and compared to other valid scales (GAF, PSP and PSRS) in a sample of 295 schizophrenia patients. The association with different parameters as external validators was assessed, including clinical remission. A comparison of the classifying properties of each scale compared to the others was made. The four instruments were equally influenced by the PANSS score, the clinical remission according Andreassen's criteria, the number of past hospitalizations and the presence of a paid working activity. These findings provide a simple threshold for the FROGS, tightly linked to the definition of functional remission, with a good convergent validity. This instrument might be easily used to facilitate the assessment of functional remission in schizophrenia.

The association of psychopathology with concurrent level of functioning and subjective well-being in persons with schizophrenia spectrum disorders

The objective is to investigate the relationship between psychopathology measured by the positive and negative syndrome scale (PANSS) and concurrent global assessment of functioning (GAF) and subjective well-being under neuroleptics (SWN) in patients with schizophrenia spectrum disorder (SSD) regarding severity of illness and disease phase. We analyzed a sample of 202 SSD patients consisting of first episode psychosis (FEP) and multiple episode psychosis (MEP) patients followed up to 12 months using linear mixed models. All PANSS syndromes except excitement were associated with GAF scores (positive syndrome: p < 0.001, d = 1.21; negative syndrome: p = 0.029, d = 0.015; disorganized syndrome: p < 0.001, d = 0.37; anxiety/depression syndrome: p < 0.001, d = 0.49), and positive symptoms had an increasing impact on global functioning with higher severity of illness (mildly ill: p = 0.039, d = 0.22; moderately ill: p < 0.001, d = 0.28; severely ill: p < 0.001, d = 0.69). SWN was associated with positive (p = 0.002, d = 0.22) and anxiety/depression (p < 0.001, d = 0.38) syndromes. Subgroup analyses showed differing patterns depending on illness severity and phase. Over all our results show different patterns of associations of psychopathology and concurrent functioning and subjective well-being. These findings contribute knowledge on the possible role of specific psychopathological syndromes for the functioning and well-being of our patients and may enable tailored treatments depending on severity and phase of illness.

Defining functioning levels in patients with schizophrenia: A combination of a novel clustering method and brain SPECT analysis

This study aims to define functioning levels of patients with schizophrenia by using a method of interpretable clustering based on a specific functioning scale, the Functional Remission Of General Schizophrenia (FROGS) scale, and to test their validity regarding clinical and neuroimaging characterization. In this observational study, patients with schizophrenia have been classified using a hierarchical top-down method called clustering using unsupervised binary trees (CUBT). Socio-demographic, clinical, and neuroimaging SPECT perfusion data were compared between the different clusters to ensure their clinical relevance. A total of 242 patients were analyzed. A four-group functioning level structure has been identified: 54 are classified as "minimal", 81 as "low", 64 as "moderate", and 43 as "high". The clustering shows satisfactory statistical properties, including reproducibility and discriminancy. The 4 clusters consistently differentiate patients. "High" functioning level patients reported significantly the lowest scores on the PANSS and the CDSS, and the highest scores on the GAF, the MARS and S-QoL 18. Functioning levels were significantly associated with cerebral perfusion of two relevant areas: the left inferior parietal cortex and the anterior cingulate. Our study provides relevant functioning levels in schizophrenia, and may enhance the use of functioning scale.

The relationships of personal resources with symptom severity and psychosocial functioning in persons with schizophrenia: results from the Italian Network for Research on Psychoses study

The relationships of personal resources with symptom severity and psychosocial functioning have never been tested systematically in a large sample of people with schizophrenia. We applied structural equation models to a sample of 921 patients with schizophrenia collected in a nationwide Italian study, with the aim to identify, among a large set of personal resources, those that may have an association with symptom severity or psychosocial functioning. Several relevant demographic and clinical variables were considered concurrently. Poor service engagement and poor recovery style, as well as older age and younger age at onset, were related to greater symptom severity and poorer social functioning. Higher resilience and higher education were related to better social functioning only. Poor problem-focused coping and internalized stigma, as well as male gender and depression, were related to symptom severity only. The explored variables showed distinctive and partially independent associations with symptom severity and psychosocial functioning. A deeper understanding of these relationships may inform treatment decisions.

Could PANSS be a useful tool in the determining of the stages of schizophrenia? A clinically operational approach

Staging in schizophrenia might be an important approach for the better treatment and rehabilitation of patients. The purpose of this study was to empirically devise a staging approach in a sample of stabilized patients with schizophrenia. One hundred and seventy patients aged ≥18 years (mean = 40.7, SD = 11.6) diagnosed by DSM-5 criteria were evaluated with the Positive and Negative Syndrome Scale (PANSS). Principal components analysis (PCA) with varimax rotation was used. The model was examined in the total sample and separately across a hypothesized stage of illness based on three age groups and between the two sexes. The PCA revealed a six factor structure for the total sample: 1) Negative, 2) Positive, 3) Depression and anxiety, 4) Excitement and Hostility, 5) Neurocognition and 6) Disorganization. The separate PCAs by stage of illness and sex revealed different patterns and quality of symptomatology. The Negative and Positive factors were stable across all examined groups. The models corresponding to different stages differed mainly in terms of neurocognition and disorganization and their interplay. Catatonic features appear more prominent in males while in females neurocognition takes two forms; one with disorganization and one with stereotype thinking with delusions. This study suggests that the three arbitrary defined stages of illness (on the basis of age) seem to reflect a progress from a preserved insight and more coherent mental functioning to disorganization and eventually neurocognitive impairment. Sexes differ in terms of the relationship of psychotic features with neurocognition. These results might have significant research and clinical implications.

Vocational Functioning in Schizophrenia Spectrum Disorders: Does Apathy Matter?

While the influence of negative symptoms on vocational outcome is well documented, the specific contribution of apathy is less explored. The current study examined the influence of apathy on vocational outcome. A total of 148 participants were included in a vocational rehabilitation study, offering cognitive remediation (CR) or cognitive behavior therapy (CBT) to address work-related issues. Clinical and functional measures were assessed on inclusion and at posttreatment after approximately 10 months. The level of apathy was not related to the acquisition of work, but higher levels of apathy predicted fewer hours worked per week during the study. Previous employment predicted future employment, and higher education predicted more hours worked and higher score on the Work Behavior Inventory. The results did not differ across interventions. Thus, despite apathy, people with schizophrenia were able to work when the barriers to employment were addressed and adequate support was given.

A cluster-analytical approach toward real-world outcome in outpatients with stable schizophrenia

BACKGROUND

This study aims to empirically identify profiles of functioning, and the correlates of those profiles in a sample of patients with stable schizophrenia in a real-world setting. The second aim was to assess factors associated with best profile membership.

METHODS

Three hundred and twenty-three outpatients were enrolled in a cross-sectional study. A two-step cluster analysis was used to define groups of patients by using baseline values for the Heinrichs-Carpenter Quality of Life Scale (QLS) total score. Logistic regression was used to construct models of class membership.

RESULTS

Our study identified three distinct clusters: 50.4% of patients were classified in the "moderate" cluster, 27.9% in the "poor" cluster, 21.7% in the "good" cluster. Membership in the "good" cluster versus the "poor" cluster was characterized by less severe negative (OR=.832) and depressive symptoms (OR=.848), being employed (OR=2.414), having a long-term relationship (OR=.256), and treatment with second-generation antipsychotics (SGAs) (OR=3.831). Nagelkerke R(2) for this model was .777.

CONCLUSIONS

Understanding which factors are associated with better outcomes may direct specific and additional therapeutic interventions, such as treatment with SGAs and supported employment, in order to enhance benefits for patients, as well as to improve the delivery of care in the community.

Decrease of functioning in remitted and non-remitted patients 16 years after a first-episode schizophrenia

In schizophrenia, a better level of functioning has been generally associated with symptomatic remission. However, this association has been supported by cross-sectional studies or by studies with a short follow-up period. Forty-eight patients with schizophrenia were evaluated by the Positive and Negative Symptoms Scale and the Social and Occupational Functioning Assessment Scale (SOFAS) at the first episode and after a mean period of 16 years. At follow-up, patients were defined as remitters (R) or non-remitters (NR) according to the Remission Schizophrenia Working Group criteria. R (n = 18; 37.5%) compared to NR showed at the first episode a lower illness severity and a better level of functioning. A functional decline was found in both groups at follow-up, even though NR showed a more than twofold reduction than R. Better SOFAS scores at follow-up were predicted by baseline SOFAS score and less severe negative symptoms at follow-up. Schizophrenia implies a functional decline over time, regardless of the symptomatic remission status with negative symptoms playing a major role.

Addressing the unmet needs of patients with persistent negative symptoms of schizophrenia: emerging pharmacological treatment options

The negative symptoms of schizophrenia represent an impairment of normal emotional responses, thought processes and behaviors, and include blunting or flattening of affect, alogia/aprosody, avolition/apathy, anhedonia, and asociality. Negative symptoms contribute to a reduced quality of life, increased functional disability, increased burden of illness, and poorer long-term outcomes, to a greater degree than positive symptoms. Primary negative symptoms are prominent and persistent in up to 26% of patients with schizophrenia, and they are estimated to occur in up to 58% of outpatients at any given time. Negative symptoms respond less well to medications than positive symptoms, and to date treatment options for negative symptoms have been limited, with no accepted standard treatment. Modest benefits have been reported with a variety of different agents, including second-generation antipsychotics and add-on therapy with antidepressants and other pharmacological classes. Recent clinical research focusing on negative symptoms target novel biological systems, such as glutamatergic neurotransmission. Different approaches include: enhancing N-methyl-D-aspartate receptor function with agents that bind directly to the glycine ligand site or with glycine reuptake inhibitors; influencing the metabotropic glutamate receptor (mGluR2/3) with positive allosteric modulators; and stimulating nicotinic acetylcholine receptors. In conclusion, the lack of clearly efficacious pharmacological treatments for the management of negative symptoms represents a significant unmet need, especially considering the importance of these symptoms on patient outcomes. Hence, further research to identify and characterize novel pharmacological treatments for negative symptoms is greatly needed.

Validation of a functional remission threshold for the Functional Remission of General Schizophrenia (FROGS) scale

OBJECTIVE

The aim of this study was to develop a functional remission threshold for the Functional Remission Of General Schizophrenia (FROGS) scale, and test its validity regarding clinical and quality of life outcomes.

DESIGN

Cross-sectional study.

INCLUSION CRITERIA

Schizophrenia according to DSM-IV-TR criteria.

DATA COLLECTION

Functioning was assessed using the FROGS and the Global Assessment of Functioning (GAF) scales; psychotic symptoms using the Positive and Negative Syndrome Scale; memory, attention, and executive functions were assessed using the California Verbal Learning Test, the D2 attention task, the Stroop color-word test, the verbal fluency test, the Trail Making Test A and B and the Wechsler Adult Intelligence Scale; and quality of life using the schizophrenia quality of life (S-QoL 18) scale.

ANALYSIS

A logistic regression analysis including the different dimensions of the FROGS was used to create a composite score to classify patients into remitted and non-remitted according a gold standard (cut-off: GAF>= 61). Receiver operating characteristics analyses were then performed to determine the area under the curve (AUC).

RESULTS

Of 137 patients enrolled, 26 were functionally remitted and 111 were not remitted according to GAF score. The AUC for the combination of the FROGS's dimensions to detect functional remission was 0.903 (p<0.001). Sensitivity and specificity for the combination of the FROGS dimensions using the Youden index were 88.5 [69.8; 97.6] and 81.1 [72.5; 87.9], respectively. Validity of this combination was satisfactory. Patients in functional remission had a lower severity of the disease, especially for PANSS negative (p<0.001) and general psychopathology (p<0.001) symptoms. Only two cognitive functions (i.e. fluency and episodic memory) were improved in remitted patients. Higher quality of life levels were globally associated with better functioning.

CONCLUSIONS

These findings provide for first accurate FROGS thresholds to detect functional remission in schizophrenia.

Empirically driven definitions of "good," "moderate," and "poor" levels of functioning in the treatment of schizophrenia

Purpose

This study used an empirical approach to identify and validate the classification of patients with schizophrenia in “good,” “moderate,” or “poor” functioning groups based on the assessment of functional measures.

Methods

Using data from a study of schizophrenia outpatients, patients were classified into functional groups using cluster analysis based on the Heinrich–Carpenter Quality of Life Scale (QLS), the 36-item Short-Form Health Survey (SF-36) Mental Component Summary Score, and a productivity measure. A three-cluster solution was chosen. Concurrent, convergent, and discriminant validity were assessed. Criteria for classifying patient functioning as “good,” “moderate,” or “poor” were established using classification and regression tree analysis.

Results

The three clusters consistently differentiated patients on the QLS, SF-36 Mental Component Summary Score, and productivity measure. The clusters also differed on other functional measures and were concordant with previous functional classifications. Concurrent, convergent, and discriminant validity were good. “Good” functioning was identified as a QLS total score ≥84.5; “moderate” and “poor” functioning were separated by a cutoff score of 15.5 on the QLS intrapsychic foundation domain. Sensitivity ranged from 86 to 93 % and specificity from 89 to 99 %.

Conclusions

The heterogeneity in functioning of schizophrenia patients can be classified reliably in an empirical manner using specific cutoff scores on commonly used functional measures.

Searching for a consensus five-factor model of the Positive and Negative Syndrome Scale for schizophrenia

Although the developers of the Positive and Negative Syndrome Scale (PANSS) grouped items into three subscales, factor analyses indicate that a five-factor model better characterizes PANSS data. However, lack of consensus on which model to use limits the comparability of PANSS variables across studies. We counted "votes" from published factor analyses to derive consensus models. One of these combined superior fit in our Caucasian sample (n=458, CFI=.970), and in distinct Japanese sample (n=164, CFI=.964), relative to the original three-subscale model, with a sorting of items into factors that was highly consistent across the studies reviewed.