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Abstract
Objective The aim of the study was to assess the utility of a novel amyotrophic lateral sclerosis (ALS) diagnostic index (ALSDI).
Methods A prospective multicenter study was undertaken on patients presenting with suspected ALS. The reference standard (Awaji criteria) was applied to all patients at recruitment. Patients were randomly assigned to a training (75%) and a test (25%) cohort. The ALSDI was developed in the training cohort and its diagnostic utility was subsequently assessed in the test cohort.
Results A total of 407 patients were recruited, with 305 patients subsequently diagnosed with ALS and 102 with a non-ALS mimicking disorder. The ALSDI reliably differentiated ALS from neuromuscular disorders in the training cohort (area under the curve 0.92, 95% confidence interval 0.89–0.95), with ALSDI ≥4 exhibiting 81.6% sensitivity, 89.6% specificity, and 83.5% diagnostic accuracy. The ALSDI diagnostic utility was confirmed in the test cohort (area under the curve 0.90, 95% confidence interval 0.84–0.97), with ALSDI ≥4 exhibiting 83.3% sensitivity, 84% specificity, and 83.5% diagnostic accuracy. In addition, the diagnostic utility of the ALSDI was confirmed in patients who were Awaji negative at recruitment and in those exhibiting a predominantly lower motor neuron phenotype.
Conclusion The ALSDI reliably differentiates ALS from mimicking disorders at an early stage in the disease process.
Classification of evidence This study provides Class I evidence that for patients with suspected ALS, the ALSDI distinguished ALS from neuromuscular mimicking disorders.
Glossary
- ALS=
- amyotrophic lateral sclerosis;
- ALSDI=
- amyotrophic lateral sclerosis diagnostic index;
- ALSFRS-R=
- Amyotrophic Lateral Sclerosis Functional Rating Scale–Revised;
- AUC=
- area under the curve;
- CI=
- confidence interval;
- CMAP=
- compound muscle action potential;
- CSP=
- cortical silent period;
- ICF=
- intracortical facilitation;
- LMN=
- lower motor neuron;
- MEP=
- motor evoked potential;
- MRC=
- Medical Research Council;
- OR=
- odds ratio;
- SICI=
- short-interval intracortical inhibition;
- TMS=
- transcranial magnetic stimulation;
- UMN=
- upper motor neuron
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Editorial page 255
Class of Evidence: NPub.org/coe
- Received April 3, 2018.
- Accepted in final form September 28, 2018.
- © 2019 American Academy of Neurology
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