Psychometric analysis in support of shortening the Scale for the Assessment of Negative Symptoms

Shortening the Alzheimer's disease assessment scale cognitive subscale

BACKGROUND

A short yet reliable cognitive measure is needed that separates treatment and placebo for treatment trials for Alzheimer's disease. Hence, we aimed to shorten the Alzheimer's Disease Assessment Scale Cognitive Subscale (ADAS-Cog) and test its use as an efficacy measure.

METHODS

Secondary data analysis of participant-level data from five pivotal clinical trials of donepezil compared with placebo for Alzheimer's disease (N = 2,198). Across all five trials, cognition was appraised using the original 11-item ADAS-Cog. Statistical analysis consisted of sample characterization, item response theory (IRT) to identify an ADAS-Cog short version, and mixed models for repeated-measures analysis to examine the effect sizes of ADAS-Cog change on the original and short versions in the placebo versus donepezil groups.

RESULTS

Based on IRT, a short ADAS-Cog was developed with seven items and two response options. The original and short ADAS-Cog correlated at baseline and at weeks 12 and 24 at 0.7. Effect sizes based on mixed modeling showed that the short and original ADAS-Cog separated placebo and donepezil comparably (ADAS-Cog original ES = 0.33, 95% CI = 0.29, 0.40, ADAS-Cog short ES = 0.25, 95% CI =0.23, 0.34).

CONCLUSIONS

IRT identified a short ADAS-cog version that separated donepezil and placebo, suggesting its clinical potential for assessment and treatment monitoring.

A very short Symptom Checklist-90-R version for routine outcome monitoring in psychotherapy; The SCL-3/7

OBJECTIVE

Routine outcome monitoring (ROM) is applied in many physical and mental health treatments. The treatment course is monitored with patient reported outcome measures (PROMs). A potential problem with PROM is response burden. This can be decreased by presenting such measures with less and better selected items. The SCL-90-R is an often used PROM for psychotherapies and a number of very short forms have been developed; the SCL-5, SCL-8, SCL-9 and SCL-10. This study aims to develop a new very short form, the symptom checklist 3 out of 7 (SCL-3/7) and to evaluate the effectiveness of these PROM with the precision relative to the complete SCL-90-R score.

METHODS

Item Response Theory analysis was applied to select the 7 best discriminating items, evenly distributed over the latent trait. A routing serves that patients only need to administer 3 items.

RESULTS

In a sample of 15,055 cases, the relative precisions of the SCL-3/7 were best for outpatients (122.7%), day care patients (111.8%) and inpatients (108.3). The SCL-5 was best for juvenile patients (110.0%), and the SCL-9 was best for addicted patients (107.2%).

CONCLUSION

The SCL-3/7 decreases patient burden in ROM and has a better precision in adult therapies than other SCL-90 short forms.

EPA guidance on assessment of negative symptoms in schizophrenia

Background

During the last decades, a renewed interest for negative symptoms (NS) was brought about by the increased awareness that they interfere severely with real-life functioning, particularly when they are primary and persistent.

Methods

In this guidance paper, we provide a systematic review of the evidence and elaborate several recommendations for the conceptualization and assessment of NS in clinical trials and practice.

Results

Expert consensus and systematic reviews have provided guidance for the optimal assessment of primary and persistent negative symptoms; second-generation rating scales, which provide a better assessment of the experiential domains, are available; however, NS are still poorly assessed both in research and clinical settings.

This European Psychiatric Association (EPA) guidance recommends the use of persistent negative symptoms (PNS) construct in the context of clinical trials and highlights the need for further efforts to make the definition of PNS consistent across studies in order to exclude as much as possible secondary negative symptoms. We also encourage clinicians to use second-generation scales, at least to complement first-generation ones.

The EPA guidance further recommends the evidence-based exclusion of several items included in first-generation scales from any NS summary or factor score to improve NS measurement in research and clinical settings. Self-rated instruments are suggested to further complement observer-rated scales in NS assessment.

Several recommendations are provided for the identification of secondary negative symptoms in clinical settings.

Conclusions

The dissemination of this guidance paper may promote the development of national guidelines on negative symptom assessment and ultimately improve the care of people with schizophrenia.

What is the Best Latent Structure of Negative Symptoms in Schizophrenia? A Systematic Review

Background

Determining the best latent structure of negative symptoms in schizophrenia could benefit assessment tools, neurobiological research, and targeted interventions. However, no review systematically evaluated studies that assessed and validated latent models of negative symptoms.

Objective

To identify and evaluate existing latent structure models in the literature of negative symptoms and to determine the best model.

Method

Systematic search of MEDLINE, EMBASE, and Scopus on July 19, 2020, for confirmatory factor analysis models of negative symptoms in patients with schizophrenia. The available evidence was assessed through 2 sets of criteria: (1) study design quality—based on negative symptoms assessment and modeling strategy and (2) psychometric quality and model fit—based on fit indices and factor definition quality.

Results

In total, 22 studies (n = 17 086) from 9 countries were included. Studies differed greatly regarding symptom scales, setting, and sample size (range = 86–6889). Dimensional models included 2–6 factors (median = 4). Twelve studies evaluated competing models and adopted appropriate instruments to assess the latent structure of negative symptoms. The 5-factor and hierarchical models outperformed unitary, 2-factor, and 3-factor models on all direct comparisons, and most of the analyses derived from the Brief Negative Symptom Scale. Considering the quality criteria proposed, 5-factor and hierarchical models achieved excellent fit in just one study.

Conclusions

Our review points out that the 5-factor and hierarchical models represent the best latent structure of negative symptoms, but the immaturity of the relevant current literature may affect the robustness of this conclusion. Future studies should address current limitations regarding psychometric properties and also address biological and clinical validity to refine available models.

The Brief Negative Symptom Scale (BNSS): Independent validation in a large sample of Italian patients with schizophrenia

Background

The Brief Negative Symptom Scale (BNSS) was developed to address the main limitations of the existing scales for the assessment of negative symptoms of schizophrenia. The initial validation of the scale by the group involved in its development demonstrated good convergent and discriminant validity, and a factor structure confirming the two domains of negative symptoms (reduced emotional/verbal expression and anhedonia/asociality/avolition). However, only relatively small samples of patients with schizophrenia were investigated. Further independent validation in large clinical samples might be instrumental to the broad diffusion of the scale in clinical research.

Methods

The present study aimed to examine the BNSS inter-rater reliability, convergent/discriminant validity and factor structure in a large Italian sample of outpatients with schizophrenia.

Results

Our results confirmed the excellent inter-rater reliability of the BNSS (the intraclass correlation coefficient ranged from 0.81 to 0.98 for individual items and was 0.98 for the total score). The convergent validity measures had r values from 0.62 to 0.77, while the divergent validity measures had r values from 0.20 to 0.28 in the main sample (n = 912) and in a subsample without clinically significant levels of depression and extrapyramidal symptoms (n = 496). The BNSS factor structure was supported in both groups.

Conclusions

The study confirms that the BNSS is a promising measure for quantifying negative symptoms of schizophrenia in large multicenter clinical studies.

Amendment of traditional assessment measures for the negative symptoms of schizophrenia

Schizophrenia research based on traditional assessment measures for negative symptoms appears to be, to some extent, unreliable. The limitations of the Positive and Negative Syndrome Scale (PANSS) and the Scale for the Assessment of Negative Symptoms (SANS) have been extensively acknowledged and should be taken into account. The aim of this study is to show how the PANSS and the SANS conflate negative symptoms and cognition and to offer alternatives for the limitations found.

METHODS

A sample of 117 participants with schizophrenia from two independent studies was retrospectively investigated. Linear regression models were computed to explore the effect of negative symptoms and illness duration as predictors of cognitive performance.

RESULTS

For the PANSS, the item "abstract thinking" accounted for the association between negative symptoms and cognition. For the SANS, the "attention" subscale predicted the performance in verbal memory, but illness duration emerged as a stronger predictor than negative symptoms for outcomes of processing speed, verbal and working memory.

CONCLUSION

Utilizing alternative models to the traditional PANSS and SANS formats, and accounting for illness duration, provide more precise evidence on the relationship between negative symptoms and cognition. Since these measures are still extensively utilized, we recommend adopting more rigorous approaches to avoid misleading results.

Current developments and challenges in the assessment of negative symptoms

Reliable and valid assessment of negative symptoms is crucial to further develop etiological models and improve treatments. Our understanding of the concept of negative symptoms has undergone significant advances since the introduction of quantitative assessments of negative symptoms in the 1980s. These include the conceptualization of cognitive dysfunction as separate from negative symptoms and the distinction of two main negative symptom factors (avolition and diminished expression). In this review we provide an overview of existing negative symptom scales, focusing on both observer-rated and self-rated measurement of negative symptoms. We also distinguish between measures that assess negative symptoms as part of a broader assessment of schizophrenia symptoms, those specifically developed for negative symptoms and those that assess specific domains of negative symptoms within and beyond the context of psychotic disorders. We critically discuss strengths and limitations of these measures in the light of some existing challenges, i.e. observed and subjective symptom experiences, the challenge of distinguishing between primary and secondary negative symptoms, and the overlap between negative symptoms and related factors (e.g. personality traits and premorbid functioning). This review is aimed to inform the ongoing development of negative symptom scales.

Identifying a system of predominant negative symptoms: Network analysis of three randomized clinical trials

BACKGROUND

Reasons for the recent mixed success of research into negative symptoms may be informed by conceptualizing negative symptoms as a system that is identifiable from network analysis. We aimed to identify: (I) negative symptom systems; (I) central negative symptoms within each system; and (III) differences between the systems, based on network analysis of negative symptoms for baseline, endpoint and change.

METHODS

Patients with chronic schizophrenia and predominant negative symptoms participated in three clinical trials that compared placebo and amisulpride to 60days (n=487). Networks analyses were computed from the Scale for the Assessment of Negative Symptoms (SANS) scores for baseline and endpoint for severity, and estimated change based on mixed models. Central symptoms to each network were identified. The networks were contrasted for connectivity with permutation tests.

RESULTS

Network analysis showed that the baseline and endpoint symptom severity systems formed symptom groups of Affect, Poor responsiveness, Lack of interest, and Apathy-inattentiveness. The baseline and endpoint networks did not significantly differ in terms of connectivity, but both significantly (P<0.05) differed to the change network. In the change network the apathy-inattentiveness symptom group split into three other groups. The most central symptoms were Decreased Spontaneous Movements at baseline and endpoint, and Poverty of Speech for estimated change.

CONCLUSIONS

Results provide preliminary evidence for: (I) a replicable negative symptom severity system; and (II) symptoms with high centrality (e.g., Decreased Spontaneous Movement), that may be future treatment targets following replication to ensure the curent results generalize to other samples.

Validity and test-retest reliability of the Persian version of the Montgomery-Asberg Depression Rating Scale

BACKGROUND AND AIMS

The Montgomery-Asberg Depression Rating Scale (MADRS) is an expert's rating tool to assess the severity and symptoms of depression. The aim of the present two studies was to validate the Persian version of the MADRS and determine its test-retest reliability in patients diagnosed with major depressive disorders (MDD).

METHODS

In study 1, the translated MADRS and the Hamilton Depression Rating Scale (HDRS) were applied to 210 patients diagnosed with MDD and 100 healthy adults. In study 2, 200 patients diagnosed with MDD were assessed with the MADRS in face-to-face interviews. Thereafter, 100 patients were assessed 3-14 days later, again via face-to-face-interviews, while the other 100 patients were assessed 3-14 days later via a telephone interview.

RESULTS

Study 1: The MADRS and HDRS scores between patients with MDD and healthy controls differed significantly. Agreement between scoring of the MADRS and HDRS was high (r=0.95). Study 2: The intraclass correlation coefficient (test-retest reliability) was r=0.944 for the face-to-face interviews, and r=0.959 for the telephone interviews.

CONCLUSION

The present data suggest that the Persian MADRS has high validity and excellent test-retest reliability over a time interval of 3-14 days, irrespective of whether the second assessment was carried out face-to-face or via a telephone interview.

Psychometric evaluation of the negative syndrome of schizophrenia

In this paper, we reviewed the available instruments for assessing the negative syndrome of schizophrenia, describing their strengths and weaknesses. Current instruments were classified into two categories according to their content validity and assessment approach as first- or second-generation instruments. The BPRS, SANS, the SENS and the PANSS belong to the first generation, while the BNSS, the CAINS and the MAP-SR belong to the second generation. The NSA can be considered a transitional instrument between the two. First-generation instruments have more content validity problems than second-generation instruments do, as they do not accurately reflect the currently accepted negative syndrome (they do not include all negative symptoms and signs or they include symptoms from other dimensions). They also have more problems relative to the use of behavioural referents instead of internal experiences of deficits when assessing symptoms, which may lead to measuring functioning instead of negative symptoms. Further research needs to be done in this area in order to ensure the evaluation of primary negative symptoms and internal experiences involved in negative symptoms rather than external behaviours.

Impact of BPRS interview length on ratings reliability in a schizophrenia trial

Signal detection in clinical trials relies on ratings reliability. We conducted a reliability analysis of site-independent rater scores derived from audio-digital recordings of site-based rater interviews of the structured Brief Psychiatric Rating Scale (BPRS) in a schizophrenia study. "Dual" ratings assessments were conducted as part of a quality assurance program in a 12-week, double-blind, parallel-group study of PF-02545920 compared to placebo in patients with sub-optimally controlled symptoms of schizophrenia (ClinicalTrials.gov identifier NCT01939548). Blinded, site-independent raters scored the recorded site-based BPRS interviews that were administered in relatively stable patients during two visits prior to the randomization visit. We analyzed the impact of BPRS interview length on "dual" scoring variance and discordance between trained and certified site-based raters and the paired scores of the independent raters. Mean total BPRS scores for 392 interviews conducted at the screen and stabilization visits were 50.4±7.2 (SD) for site-based raters and 49.2±7.2 for site-independent raters (t=2.34; p=0.025). "Dual" rated total BPRS scores were highly correlated (r=0.812). Mean BPRS interview length was 21:05±7:47min ranging from 7 to 59min. 89 interviews (23%) were conducted in less than 15min. These shorter interviews had significantly greater "dual" scoring variability (p=0.0016) and absolute discordance (p=0.0037) between site-based and site-independent raters than longer interviews. In-study ratings reliability cannot be guaranteed by pre-study rater certification. Our findings reveal marked variability of BPRS interview length and that shorter interviews are often incomplete yielding greater "dual" scoring discordance that may affect ratings precision.

Identification of psychopathological course trajectories in schizophrenia

Course trajectory analyses have been performed primarily for treatment response in acute episodes of schizophrenic disorders. As yet, corresponding data for the long-term course are lacking. Within a multicenter prospective observational study, 268 patients with schizophrenia were assessed at discharge from hospital and followed up after 6, 12, 18, and 24 months. A latent class growth analysis was performed on the scores from the Positive and Negative Syndrome Scale (PANSS). A two-class conditional latent class model showed the best data fit (Entropy: 0.924). The model divided the sample into a group with amelioration in all PANSS subscales (60%) and a group with stable positive/negative and deteriorating general psychopathology symptoms (40%). Global functioning (GAF score), gender, age, living situation and involuntary admission predicted course trajectory class membership. The model was predictive of significant differences between the two groups in health care service costs and quality of life. The results underline the heterogeneous course of the illness, which ranged from amelioration to deterioration over a 2-year period. Statistical models such as trajectory analysis could help to identify more homogenous subtypes in schizophrenia.

Scale for the Assessment of Negative Symptoms structure in first episode psychosis

Previous studies in schizophrenia samples suggest negative symptoms can be categorized as expressivity or experiential. This study examines the structure of the Scale for the Assessment of Negative Symptoms (SANS) at two separate interviews in a first episode psychosis (FEP) sample. SANS structure was determined with principal components analysis in a schizophrenia spectrum (SSD, N=191) and non-schizophrenia spectrum (NSSD, N=246) sample at first presentation. Confirmatory factor analysis (CFA) was conducted in the entire FEP sample (N=197) at a follow-up assessment. A three factor model solution was extracted in both SSD and NSSD at first presentation. The three components, consisting of expressivity, experiential and alogia/inattention components, explained 26.1%, 16.6% and 13.6% of the variance respectively in SSD. In NSSD the same three components explained 24.2%, 17.9% and 13.1% of the variance respectively. CFA at follow-up showed similar model fit for both the original SANS five factor and for a three factor model solution. The results indicate that either a three or five factor SANS model solution may be appropriate in a psychosis sample inclusive of both SSD and NSSD. The findings also provide initial support for expressivity and experiential domain research in NSSD.