Innovations In Clinical Neuroscience

SEP-OCT 2014

A peer-reviewed, evidence-based journal for clinicians in the field of neuroscience

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[ V O L U M E 1 1 , N U M B E R 9 – 1 0 , S E P T E M B E R – O C T O B E R 2 0 1 4 ] Innovations in CLINICAL NEUROSCIENCE 35 dependent on prevalence and can be low even when there is high concordance on low-prevalence conditions. The AUC, interpreted as t he probability that a randomly selected clinical case will score higher on the test than a non-case, has been proposed to correct this problem 18 and can be used in situations in which the predictor is a dichotomy. In this case, the AUC equals (SN+SP)/2. 19 Following Agresti, 2 0 we considered the AUC to be excellent evidence of concordance if 0.90 or greater, good evidence of concordance if between 0.80 and 0.90, acceptable although only average if between 0.70 and 0.80, and poor if below 0.70. 20 For each of the category comparisons with the C–SSRS, we report the following additional information shown in Table 2: 2 1,22 absolute numbers of participants in each cell of the cross-tabulation (those positive for a category on the test instrument and the C–SSRS, those negative on both scales, those positive on the test instrument but negative on the C–SSRS, those negative on the test instrument but positive on the C–SSRS) and McNemar's test of the significance of the comparison. We also report sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). These calculations require a "gold standard" measure of the presence of a construct (e.g., illness, symptom). Given the current putative status of the C–SSRS per FDA publications, it was used as the gold standard criterion measure. Thus, sensitivity is defined here as the probability of the test (i.e., the ISST-Plus or the S-STS, respectively) identifying a patient as meeting criteria for a particular FDA category (using the C–SSRS as the criterion). Specificity is defined as the probability of the test concluding that the subject does not meet criteria for the FDA category (using the C–SSRS results as the criterion). The PPV is defined as the probability that a subject who is identified as meeting criteria for a category on the test actually has the condition (using the C–SSRS as the criterion). In contrast, the NPV is the probability that a subject identified as not having the condition does not meet criteria based on the results of the C–SSRS. We also report overall agreement between the clinician-rated versions of ISST-Plus and S-STS. In addition, we tabulate the combinations of active suicidal ideation that are captured on the ISST-Plus and S-STS but not on the C–SSRS. RESULTS Study subjects. Forty-five subjects were interviewed. The mean (standard deviation [SD]) age of the sample was 39.9 (15.0) years, with a range of 19 to 73 years. For gender, 44.4 percent of the subjects self- identified as male. For race, 73.3 percent self-identified as white, 24 percent as black, and 2.2 percent as mixed race. The mean age of first psychiatric symptom was 16.6 (10.0) years with a range of 5 to 42 years. The mean age of first psychiatric treatment was 24.5 (13.3) years, with a range of 5 to 58 years. The mean age of first psychiatric hospitalization was 30.8 (14.7) years, with a range of 10 to 68 years. The mean number of past suicide attempts was 2.1 (2.8) with a range of 0 to 13. Suicide severity distribution is shown in Table 3. Table 3 illustrates that the sample studied had suicide severities well distributed across the full spectrum of severity. Agreement between the (ISST- Plus and C–SSRS) and (S-STS and C–SSRS). Table 4, together FIGURE 2. FDA categories to which suicide assessment scales should map per FDA Guidance 2012 and additional categories from FDA Guidance 2010

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