Improving Assessment of Cognitive Impairment after Spinal Cord Injury: Methods to Reduce the Risk of Reporting False Positives

J. Clin. Med., 2023 · DOI: 10.3390/jcm12010068 · Published: December 21, 2022

Spinal Cord Injury Mental Health Neurology

Simple Explanation

This study addresses the problem of misclassifying mild cognitive impairment (MCI) in adults with spinal cord injury (SCI). It argues that relying solely on comparing an individual's cognitive test scores to a normative group (nM-method) can lead to inaccurate MCI diagnoses. The authors propose incorporating an assessment of premorbid intelligence (pIQ-method), which estimates a person's cognitive ability before the injury. By comparing current cognitive function to estimated premorbid function, clinicians can better identify genuine cognitive decline. The study used simulated data to compare the two assessment methods (nM-method vs. pIQ-method) and found that relying only on the nM-method can lead to a significant number of false positive MCI diagnoses in people with SCI.

Study Duration

12-months post-injury

Participants

62 adults with SCI informed simulation procedures, simulated data for 500,000 adults with SCI

Evidence Level

Not specified

Key Findings

1
Exclusive reliance on norm-referenced methods (nM-method) resulted in one in five to one in 13 potential false positive MCI classifications.
2
The rate of disagreement between the nM-method and the premorbid intelligence method (pIQ-method) depended on the chosen standard deviation cut-off and the assumed base rate of MCI.
3
The likelihood of disagreement between the two methods was highest when a smaller standard deviation (1 SD) was used to classify impairment, irrespective of changes in the base rate of MCI.

Research Summary

This study investigates the potential for misclassification of mild cognitive impairment (MCI) in adults with spinal cord injury (SCI) when relying solely on norm-referenced assessments, without considering premorbid intelligence. Using simulated data, the study compares norm-referenced (nM-method) and premorbid intelligence (pIQ-method) approaches to MCI screening, highlighting the potential for false positive MCI classifications when premorbid cognitive function is not considered. The findings suggest that a comprehensive MCI assessment approach, incorporating both norm-referenced and premorbid cognitive function measures, is crucial for accurate diagnosis and to avoid overestimating the prevalence of MCI after SCI.

Practical Implications

Improve MCI Assessment

Incorporate premorbid intelligence measures alongside norm-referenced tests to enhance the accuracy of MCI diagnosis in SCI patients.

Standardize Assessment Practices

Develop standardized assessment criteria and practices for MCI diagnosis in SCI to reduce heterogeneity and improve the reliability of research findings.

Develop SCI-Specific Norms

Create SCI-specific norms for existing neuropsychological screens and develop new tests tailored to the unique testing needs of the SCI population.

Study Limitations

1
The NUCOG is not a gold standard screen for MCI assessment.
2
The correlation between the NUCOG and the Test of Premorbid Functioning in this simulated sample of adults with SCI was 0.42.
3
The NUCOG has been shown to have suboptimal structural validity in an SCI sample.

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