Empirical evaluation of the factorial structure of clinical symptoms in schizophrenia: Effects of typical neuroleptics on the brief psychiatric rating scale

Harvey, Philip D.; Davidson, Michael; White, Leonard; Keefe, Richard S.E.; Hirschowitz, Jack; Mohs, Richard C.; Davis, Kenneth L.

doi:10.1016/0006-3223(95)00486-6

Cited by 34 publications

(26 citation statements)

References 17 publications

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“…The data simulation was performed using R software 2.6.2.; vectors ε j , f m and C were generated using the function rnorm and δ j using runif. (Bell et al, 1994;Fresan et al, 2005;Honey et al, 2003;Kay et al, 1990;Lancon et al, 1999;Lee et al, 2003;Lindenmayer et al, 2004;Loza et al, 2003;Lykouras et al, 2000;Salokangas et al, 2002;Villalta-Gil et al, 2006) 11 --1 8 -2 BPRS (Adachi et al, 2000;Harvey et al, 1996;Lachar et al, 2001;Ventura et al, 2000) 4 --2 1 1 -BAI (Beck, 1991;Chapman et al, 2009;Kabacoff et al, 1997;Steer et al, 1995;Steer et al, 1993) (Gabryelewicz et al, 2004;Galinowski et al, 1995;Lee et al, 2003;Parker et al, 2003;Serretti et al, 1999) 5 3 2 ----BDI (Basker et al, 2007;Bonicatto et al, 1998;Bonilla et al, 2004;Gorenstein et al, 1999;Grunebaum et al, 2005;Helm et al, 2003;Jo et al, 2007;Killgore, 1999;Munoz et al, 2007;Powell, 2003;Salamero et al, 1994;Shek, 1990;Steer et al, 1989;Uslu et al, 2008;Wang et al, 2005) …”

Section: Resultsmentioning

confidence: 99%

Sample size requirements for the internal validation of psychiatric scales

Rouquette

Falissard

2011

Int J Methods Psych Res

211

121

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To cite this version:Alexandra Rouquette, Bruno Falissard. Sample size requirements for the internal validation of psychiatric scales.. International Journal of Methods in Psychiatric Research, Wiley, 2011, 20 (4) Abstract:The ratio of subjects to variables (N/p), as a rule to calculate the sample size required in internal validity studies on measurement scales, has been recommended without any strict theoretical or empirical basis being provided. The purpose of the present study was to develop a tool to determine sample size for these studies in the field of psychiatry. First, a literature review was carried out to identify the distinctive features of psychiatric scales. Then, two simulation methods were developed to generate data according to: 1/ the model for factor structure derived from the literature review and 2/ a real dataset. This enabled the study of the quality of solutions obtained from principal component analysis or Exploratory Factor Analysis (EFA) on various sample sizes. Lastly, the influence of sample size on the precision of Cronbach"s alpha coefficient was examined. The N/p ratio rule is not upheld by this study: short scales do not allow smaller sample size. As a rule of thumb, if one"s aim is to reveal the factor structure, a minimum of 300 subjects is generally acceptable but should be increased when the number of factors within the scale is large, when EFA is used and when the number of items is small.

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Section: Resultsmentioning

confidence: 99%

Sample size requirements for the internal validation of psychiatric scales

Rouquette

Falissard

2011

Int J Methods Psych Res

211

121

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“…If the distinction between reality distortion and disorganization reflects distinct biological processes, treatment response could be assessed more informatively by separate measures of these two domains, rather than by a "positive symptom" factor which includes elements of both. Harvey et al (1996) reported a similar division in a model derived from exploratory factor analysis. The symptoms loading on several of their factors differed from our model, and their five-factor model did not fit well in their original data set; nor did it fit as well in our data as the other models considered.…”

Section: Comparison To Other Factor Ratingsmentioning

confidence: 63%

“…The stability of our factor structure before and after treatment with clozapine supports the assertion that these factors retain their internal validity despite treatment effects, and may be used to give meaningful summaries of treatment effects on symptoms. Stability of schizophrenic symptom clusters over time despite medication effects has also been reported in schizophrenic patients not selected for treatment resistance (Arndt et al 1995, Goldman et al 1991Harvey et al 1996).…”

Section: Comparison To Other Factor Ratingsmentioning

confidence: 81%

“…Sources of variability in the symptom domains reported include: (1) potential differences in pathology and symptom associations among distinct patient populations; (2) differences in the instruments used, with some (e.g., Scale for Assessment of Positive Symptoms (Andreasen 1984)) and Scale for the Assessment of Negative Symptoms (Andreasen 1989)) omitting the affective domain entirely, despite the common presence of these symptoms in patients with schizophrenia; and (3) variations in factor analytic methods. In addition, only a few reports (Arndt et al 1995;Harvey et al 1996;Goldman et al 1991) have addressed whether factor solutions are stable over time despite medication changes.…”

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confidence: 99%

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Novel Factor-Based Symptom Scores in Treatment Resistant Schizophrenia Implications for Clinical Trials

McMahon¹,

Kelly²,

Kreyenbuhl

et al. 2002

Neuropsychopharmacology

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To study the factor structure of symptoms in patients with treatment resistant schizophrenia and whether it is altered by treatment, we analyzed ratings on the Brief Psychiatric Rating Scale (BPRS) from two independent groups of patients with treatment resistant schizophrenia. With confirmatory factor analysis of pre-clozapine BPRS scores in 1074 patients in an administrative data base, the Clozapine Authorization and Monitoring Program (CAMP), we assessed the fit of published factor models and developed a better-fitting model. Model fit was validated in an independent group of 197 research unit participants. Stability of model fit six months post-clozapine was assessed in 834 CAMP patients. A new 4-factor model (negative symptoms, reality distortion, disorganization, and anxiety/ depression) had better fit in both data sets than two commonly used factor models, and also fit better postclozapine. We recommend these four factor scores as clinical trial outcomes in patients withSchizophrenia is a disease with a highly variable course and symptoms. On broad-ranging symptom inventories such as the Brief Psychiatric Rating Scale (BPRS) (Overall and Gorham 1988) and Positive and Negative Symptom Scale (PANSS), patients typically display a wide variety of disordered behavior of varying severity. With some variation in how symptoms are clustered together, factor analytic studies have suggested the presence of certain broad symptom domains (reality distortion, disorganization, negative symptoms and anxiety/ depression) underlying this heterogeneity (Buchanan and Carpenter 1994). Sources of variability in the symptom domains reported include: (1) potential differences in pathology and symptom associations among distinct patient populations; (2) differences in the instruments used, with some (e.g., Scale for Assessment of Positive Symptoms (Andreasen 1984)) and Scale for the Assessment of Negative Symptoms (Andreasen 1989)) omitting the affective domain entirely, despite the common presence of these symptoms in patients with schizophrenia; and (3) variations in factor analytic methods. In addition, only a few reports (Arndt et al. 1995;Harvey et al. 1996;Goldman et al. 1991) 26 , NO . 4 The effectiveness of medications may vary across these symptom domains, so that domain-specific symptom scores are logical outcome measures for clinical trials. Symptom domain scores used in psychiatric clinical trials, however, have been inconsistent in the symptoms included. Nicholson et al. (1995) found no less than ten BPRS-based definitions of positive symptoms and four definitions of negative symptoms in recent psychiatric literature. Commonly used BPRS scorings group symptoms of disorganization and reality distortion together in a "positive" symptom score, despite the emerging evidence that these symptoms fall into two distinct domains.The goal of the current study is to develop and validate domain-specific BPRS symptom scores suitable for use as outcome measures in clinical trials in patients with treatment resistant schizophr...

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“…Outcomes on the BPRS were analyzed using the 5-factor solution described by Harvey et al [43], which includes the following subscales: positive, negative, disorganization, belligerence, and affect. Each item was rated from 1 (not present) to 7 (extremely severe), with higher scores indicating more severe symptoms.…”

Section: Methodsmentioning

confidence: 99%