Aims The laboratory diagnosis of demyelinating inflammatory disorders (DIDs) relies on both intrathecal oligoclonal band (OCB) positivity and IgG index. Although OCB typing remains the gold-standard test for DIDs, it can be laborious and ambiguous, complicating diagnostics, and unduly increasing diagnostic time. We examined whether serum or cerebrospinal fluid (CSF) parameters can classify OCB types and, thus, be used as a replacement test to standard OCB typing.
Methods We retrospectively analysed >1000 prospectively collected samples of patients with DIDs and quantified albumin and IgG levels in the CSF and serum. We determined OCB types by isoelectric focusing combined with immunofixation and evaluated the diagnostic accuracies of IgG and albumin indices in discriminating OCB types by receiver operating characteristic curves and multinomial regression.
Results An IgG index cut-off of 0.589 differentiated types 2/3 from types 1/4 (area under the curve 0.780, 95% CI 0.761 to 0.812, p<0.001; specificity: 71.10%, sensitivity: 73.45%). Albumin quotient cut-off values of 6.625 and of 6.707 discriminated type 1 from type 4 and type 2 from type 3, respectively (specificity: <55%, sensitivity: <75%). Female sex, age, IgG index, CSF IgG and serum albumin were associated with different OCB types.
Conclusions Our study reveals that IgG and albumin index can differentiate OCB types with adequate accuracy, especially if refined by age and gender.
- evidence-based practice
Data availability statement
Data are available upon reasonable request.
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Handling editor Tahir S Pillay.
A-FAM and GPC contributed equally.
Contributors MB: conceived the study; collected data; performed research; provided important reagents; revised the paper. AK: conceived the study; collected data; provided important reagents; revised the paper. A-FM: conceived the study; designed research/study; analysed data; performed research; wrote the paper. GPC: conceived the study; designed research/study; supervised the study; revised the paper. All listed authors have read and approved the final version of the manuscript and provided consent for its publication.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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