Innovations In Clinical Neuroscience

NOV-DEC 2017

A peer-reviewed, evidence-based journal for clinicians in the field of neuroscience

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35 ICNS INNOVATIONS IN CLINICAL NEUROSCIENCE November-December 2017 • Volume 14 • Number 11–12 O R I G I N A L R E S E A R C H that showed DIF favoring the United States (as evidenced by CC-), indicating the item is more reliably and uniformly scored for the severity level in the United States than in India. Every moderate-to-large DIF was in favor of the non-United States geographical region under investigation. Of all the items of the NSF, N3 Poor Rapport showed the most moderate and large DIF (n=13; 86.67%) across countries, with seven countries reporting large DIF. Similarly, N6 Lack of Spontaneity and Flow of Conversation showed moderate and large DIF for 66.67% countries (n=10). Canada was the only country to report no DIF across all items of the expressive deficit domain. With respect to the experiential deficit factor, there were no geographical regions that showed moderate-to-large DIF for all items. Out of all the factors of the NSF, item G16 Active Social Avoidance reported negligible DIF for 14 of the 15 countries investigated (93.33%). Large DIF was observed for N2 Emotional Withdrawal and N4 Passive Apathetic Social Withdrawal for Brazil and India. Brazil demonstrated the largest DIF classifications (CC) across all countries (i.e., five of the seven NSF items). Seven regions demonstrated no DIF across all items of the PANSS experiential deficit factor (South America-Mexico, Belgium-Netherlands, Nordic, Great Britain, Eastern Europe, Russia, and Spain), as compared with only one region (Canada) that showed no DIF for the PANSS expressive deficit domain. Similar to the findings observed in the PANSS expressive deficit domain, India was the only country to show large DIF in favor of the United States, indicating that the item is more reliably and uniformly scored for the severity level within the United States. Overall, there were many fewer observed items with large DIF for PANSS experiential deficits (only 14 of 45 observed cases of moderate-to-large DIF). DISCUSSION Despite the multiple psychometric analyses of the PANSS over the past 30 years, this study is the first to assess performance on the PANSS expressive and experiential deficit factors across varying levels of symptom severity (borderline to extremely mentally ill) and across multiple (i.e., 15) geographical regions. Our first aim was to assess whether the items attributed to the PANSS expressive and experiential deficit factors were observed within our dataset. To this end, the expressive and experiential items of the PANSS NSF show good model fit and distinct deficits in these two domains, indicating that the PANSS expressive deficit and experiential deficit factors can be reliably used as distinct efficacy endpoints to further characterize negative symptoms. Our second aim was to assess performance of the items attributed to the PANSS expressive and experiential deficits to identify DIF across geographic regions. Our findings showed that, similar to previous studies, 18,19 negative symptom items show increased variability in scores across raters. Specifically, we showed DIF across multiple countries for most items of the PANSS expressive deficit. Having determined that negative symptoms of schizophrenia are particularly difficult to assess due to the challenge of eliciting reliable information from a potentially disengaged subject during a clinical interview, this study evaluated differences in PANSS expressive and experiential deficits across 15 geographic regions. The observed differences can help inform protocol development, elucidate ways to customize rater training and data review, and determine endpoints for clinical trials that will subsequently affect accuracy of symptom presentation and trial outcome. The present study found that all items of the PANSS experiential and expressive deficit factors showed evidence of DIF across geographic regions after matching subjects on PANSS total score. Items of the PANSS expressive deficit factor showed more DIF with the United States compared with other geographical regions. Specifically, for N3 Poor Rapport, 13 of the 15 geographic regions had moderate-to-large DIF with the United States than any other item. N3 Poor Rapport assesses the rater's opinion of the subject's interpersonal empathy, openness in conversation, and sense of closeness, interest, or involvement with the rater. With the available data from our sample, it is unclear how to interpret these findings, given that we do not have information on subject disposition (i.e., hospitalized or non-hospitalized, length of hospitalization); good rapport could be expected with longer inpatient stays as symptoms improve and subjects become more familiar with raters, but such differences cannot be assessed with the available data. We therefore hypothesize that cultural differences between raters might have affected the scoring of N3 Poor Rapport in the geographical regions examined due to distinctive interpersonal norms. While assessing the influence of language and culture on the PANSS across seven geographic regions, Yavorsky et al 35 found differences in the rating of negative symptoms, particularly poor rapport, due to the ways in which different groups conceptualize N3 Poor Rapport. Moreover, N3 Poor Rapport characterizes behaviors that are perhaps less accepted in the United States, Canada, and India, as compared with in other geographic regions where they might be more tolerated. Item N1 Blunted Affect showed DIF favoring seven geographic regions compared with the United States; item N6 Lack of Spontaneity and Flow of Conversation showed DIF favoring nine geographic regions as compared with the United States, with India being the only region that showed DIF favoring the United States. N1 Blunted Affect is scored solely on the rater's observation of the subject's physical manifestations. However, Mesquita and Frijda 36 reviewed evidence that there are cultural similarities and differences in all components of the affect process, including in TABLE 3. Factor loadings and model fit SEVERITY LEVELS PANSS NSF PANSS expressive deficits, % variance 55.12% N1 blunted Affect 0.749 N3 Poor Rapport 0.696 N6 Lack of Spontaneity 0.783 G7 Motor Retardation 0.744 PANSS experiential deficits, % variance 14.65% N2 Emotional Withdrawal 0.666 N4 Passive Apathetic Social Withdrawal 0.779 G16 Active Social Avoidance 0.886 Chi-squared 99.215 P* ≤0.001 Root mean square error of approximation (RMSEA)** 0.045 Comparative fix index (CFI)*** 0.923 Tucker-Lewis index (TLI)**** 0.913 Goodness-of-fix index (GFI)***** 0.906 PANSS: Positive and Negative Syndrome Scale; NSF: negative symptom factor; *if significance level set at P<0.05; **RMSEA≤0.05 is "good fit;" ***CFI≥0.90 is "satisfactory fit;" ****TLI≥0.90 is "satisfactory fit;" *****GFI≥0.90 is "satisfactory fit"

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