Validity of carbohydrate deficient transferrin and other markers as diagnostic aids in the detection of alcohol related seizures

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Abstract
OBJECTIVE The role of alcohol misuse in the genesis of seizures is probably often undetected. The aim was to investigate the utility of carbohydrate deficient transferrin (CDT) compared with other biomarkers and clinical examination in the diagnosis of alcohol related seizures. METHODS The study included consecutively 158 seizure patients—83 men and 75 women—with mean age 45 (16–79) years. Seizures related to alcohol use were identified by a score ⩾8 in the alcohol use disorders identification test (AUDIT positive). AUDIT was applied as the gold standard to which sensitivity and specificity of the various markers were related. Blood samples were obtained from 150 patients on admission and analysed for ethanol, liver enzymes, and CDT, using AXIS Biochemicals' %CDT-TIA kit. RESULTS 53 patients (34%) were AUDIT positive. Using the commonly applied decision value for %CDT of 5.0%, a sensitivity of 41% and a specificity of 84% were obtained. Analysis of receiver operator characteristics (ROC) curves disclosed an optimal cut off value for %CDT of 5.4%, which yielded a sensitivity of 39% and a specificity of 88%. At a specificity of 80%, the sensitivity was 43% for %CDT and 26% for GGT. The %CDT sensitivity was markedly higher for men than for women. Compared with GGT, ASAT, ALAT, and ASAT/ALAT ratio, CDT was the best single biomarker for alcohol related seizures. However, even in the subgroup of withdrawal seizures, the sensitivity level barely exceeded 50%. Clinicians scored alcohol as the main cause of the seizure in only 19 cases (12%). In 38 (24%) cases, clinicians suspected that alcohol had a role (sensitivity of 62% at a specificity of 89%). Their ability to identify AUDIT positive patients was better than that of any biomarker, but many cases were missed. Agreement of clinicians' scores to CDT was only fair (κ=0.28). CDT concentrations were significantly increased among alcohol abstaining patients on enzyme-inducing antiepileptic drugs. Six out of 16 patients with false positive CDT results were exposed to such drugs. CONCLUSIONS CDT is not recommended as a stand alone marker for alcohol related seizures, but may provide a useful contribution to the overall diagnostic investigation of seizures. Confirmatory studies are needed as to the apparent vulnerability of CDT to antiepileptic drugs.