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Item response analysis of the Positive and Negative Syndrome Scale.

Santor DA, Ascher-Svanum H, Lindenmayer JP, Obenchain RL - BMC Psychiatry (2007)

Bottom Line: Statistical models based on item response theory were used to examine (a) the performance of individual Positive and Negative Syndrome Scale (PANSS) items and their options, (b) the effectiveness of various subscales to discriminate among individual differences in symptom severity, and (c) the appropriateness of cutoff scores recently recommended by Andreasen and her colleagues (2005) to establish symptom remission.These analyses did identify some items which might be further improved for measuring individual severity differences or for defining remission thresholds.Findings also suggest that the Positive and Negative subscales are more sensitive to change than the PANSS total score and, thus, may constitute a "mini PANSS" that may be more reliable, require shorter administration and training time, and possibly reduce sample sizes needed for future research.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Psychology, University of Ottawa, Ottawa, Canada, and The Provincial Centre of Excellence for Child and Youth Mental Health, Ottawa, Ontario, Canada. dsantor@uottawa.ca

ABSTRACT

Background: Statistical models based on item response theory were used to examine (a) the performance of individual Positive and Negative Syndrome Scale (PANSS) items and their options, (b) the effectiveness of various subscales to discriminate among individual differences in symptom severity, and (c) the appropriateness of cutoff scores recently recommended by Andreasen and her colleagues (2005) to establish symptom remission.

Methods: Option characteristic curves were estimated using a nonparametric item response model to examine the probability of endorsing each of 7 options within each of 30 PANSS items as a function of standardized, overall symptom severity. Our data were baseline PANSS scores from 9205 patients with schizophrenia or schizoaffective disorder who were enrolled between 1995 and 2003 in either a large, naturalistic, observational study or else in 1 of 12 randomized, double-blind, clinical trials comparing olanzapine to other antipsychotic drugs.

Results: Our analyses show that the majority of items forming the Positive and Negative subscales of the PANSS perform very well. We also identified key areas for improvement or revision in items and options within the General Psychopathology subscale. The Positive and Negative subscale scores are not only more discriminating of individual differences in symptom severity than the General Psychopathology subscale score, but are also more efficient on average than the 30-item total score. Of the 8 items recently recommended to establish symptom remission, 1 performed markedly different from the 7 others and should either be deleted or rescored requiring that patients achieve a lower score of 2 (rather than 3) to signal remission.

Conclusion: This first item response analysis of the PANSS supports its sound psychometric properties; most PANSS items were either very good or good at assessing overall severity of illness. These analyses did identify some items which might be further improved for measuring individual severity differences or for defining remission thresholds. Findings also suggest that the Positive and Negative subscales are more sensitive to change than the PANSS total score and, thus, may constitute a "mini PANSS" that may be more reliable, require shorter administration and training time, and possibly reduce sample sizes needed for future research.

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Related in: MedlinePlus

Option characteristic curves and expected item total score for Item 19: Mannerisms and posturing. Option characteristic curves (solid lines) and expected item total score (dashed line) are plotted as a function of scores on the General Psychopathology Subscale from the PANNS, expressed as standard normal scores (lower x-axis) and expected total scores (upper x-axis). Option characteristic curves (solid lines) overlap between Options 1 and 2 but generally well differentiated. However, options are generally only endorsed at more severe levels of symptomatology. Option 1 was most likely to be endorsed than any other option, in over half the sample, namely with individuals scoring less than 81 on the 30-item PANSS.
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Figure 5: Option characteristic curves and expected item total score for Item 19: Mannerisms and posturing. Option characteristic curves (solid lines) and expected item total score (dashed line) are plotted as a function of scores on the General Psychopathology Subscale from the PANNS, expressed as standard normal scores (lower x-axis) and expected total scores (upper x-axis). Option characteristic curves (solid lines) overlap between Options 1 and 2 but generally well differentiated. However, options are generally only endorsed at more severe levels of symptomatology. Option 1 was most likely to be endorsed than any other option, in over half the sample, namely with individuals scoring less than 81 on the 30-item PANSS.

Mentions: Item 19 from the PANSS assesses Mannerisms and Posturing, which is defined as "Unnatural movements or posture characterized as awkward, stilted, disorganized, or bizarre". Option characteristic curves for this item, Figure 5, tend to increase less quickly than those for Item 1 (Delusions.) As a result, Options 2 through 6 of Item 19 are likely to be endorsed at much higher severity levels than the corresponding options of Item 1. Item 19 (Mannerisms and Posturing) could, therefore, be termed a "hard" item.


Item response analysis of the Positive and Negative Syndrome Scale.

Santor DA, Ascher-Svanum H, Lindenmayer JP, Obenchain RL - BMC Psychiatry (2007)

Option characteristic curves and expected item total score for Item 19: Mannerisms and posturing. Option characteristic curves (solid lines) and expected item total score (dashed line) are plotted as a function of scores on the General Psychopathology Subscale from the PANNS, expressed as standard normal scores (lower x-axis) and expected total scores (upper x-axis). Option characteristic curves (solid lines) overlap between Options 1 and 2 but generally well differentiated. However, options are generally only endorsed at more severe levels of symptomatology. Option 1 was most likely to be endorsed than any other option, in over half the sample, namely with individuals scoring less than 81 on the 30-item PANSS.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211479&req=5

Figure 5: Option characteristic curves and expected item total score for Item 19: Mannerisms and posturing. Option characteristic curves (solid lines) and expected item total score (dashed line) are plotted as a function of scores on the General Psychopathology Subscale from the PANNS, expressed as standard normal scores (lower x-axis) and expected total scores (upper x-axis). Option characteristic curves (solid lines) overlap between Options 1 and 2 but generally well differentiated. However, options are generally only endorsed at more severe levels of symptomatology. Option 1 was most likely to be endorsed than any other option, in over half the sample, namely with individuals scoring less than 81 on the 30-item PANSS.
Mentions: Item 19 from the PANSS assesses Mannerisms and Posturing, which is defined as "Unnatural movements or posture characterized as awkward, stilted, disorganized, or bizarre". Option characteristic curves for this item, Figure 5, tend to increase less quickly than those for Item 1 (Delusions.) As a result, Options 2 through 6 of Item 19 are likely to be endorsed at much higher severity levels than the corresponding options of Item 1. Item 19 (Mannerisms and Posturing) could, therefore, be termed a "hard" item.

Bottom Line: Statistical models based on item response theory were used to examine (a) the performance of individual Positive and Negative Syndrome Scale (PANSS) items and their options, (b) the effectiveness of various subscales to discriminate among individual differences in symptom severity, and (c) the appropriateness of cutoff scores recently recommended by Andreasen and her colleagues (2005) to establish symptom remission.These analyses did identify some items which might be further improved for measuring individual severity differences or for defining remission thresholds.Findings also suggest that the Positive and Negative subscales are more sensitive to change than the PANSS total score and, thus, may constitute a "mini PANSS" that may be more reliable, require shorter administration and training time, and possibly reduce sample sizes needed for future research.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Psychology, University of Ottawa, Ottawa, Canada, and The Provincial Centre of Excellence for Child and Youth Mental Health, Ottawa, Ontario, Canada. dsantor@uottawa.ca

ABSTRACT

Background: Statistical models based on item response theory were used to examine (a) the performance of individual Positive and Negative Syndrome Scale (PANSS) items and their options, (b) the effectiveness of various subscales to discriminate among individual differences in symptom severity, and (c) the appropriateness of cutoff scores recently recommended by Andreasen and her colleagues (2005) to establish symptom remission.

Methods: Option characteristic curves were estimated using a nonparametric item response model to examine the probability of endorsing each of 7 options within each of 30 PANSS items as a function of standardized, overall symptom severity. Our data were baseline PANSS scores from 9205 patients with schizophrenia or schizoaffective disorder who were enrolled between 1995 and 2003 in either a large, naturalistic, observational study or else in 1 of 12 randomized, double-blind, clinical trials comparing olanzapine to other antipsychotic drugs.

Results: Our analyses show that the majority of items forming the Positive and Negative subscales of the PANSS perform very well. We also identified key areas for improvement or revision in items and options within the General Psychopathology subscale. The Positive and Negative subscale scores are not only more discriminating of individual differences in symptom severity than the General Psychopathology subscale score, but are also more efficient on average than the 30-item total score. Of the 8 items recently recommended to establish symptom remission, 1 performed markedly different from the 7 others and should either be deleted or rescored requiring that patients achieve a lower score of 2 (rather than 3) to signal remission.

Conclusion: This first item response analysis of the PANSS supports its sound psychometric properties; most PANSS items were either very good or good at assessing overall severity of illness. These analyses did identify some items which might be further improved for measuring individual severity differences or for defining remission thresholds. Findings also suggest that the Positive and Negative subscales are more sensitive to change than the PANSS total score and, thus, may constitute a "mini PANSS" that may be more reliable, require shorter administration and training time, and possibly reduce sample sizes needed for future research.

Show MeSH
Related in: MedlinePlus