Innovations In Clinical Neuroscience

SEP-OCT 2014

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

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Innovations in CLINICAL NEUROSCIENCE [ 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 ] 68 psychometric data on the C–SSRS concluded the "C–SSRS requires more study before it can be recommended for use[...]" 19 This r elatively light attention is worrisome since not all scales that are widely used or accorded gold standard status continue to live up to the level expected of them. 21 MOUNTING CRITICISM In the case of the C–SSRS, criticism of the instrument has been mounting. 16,19,20 In particular, the third author of this article (D.S.) frequently hears from investigators—those who are now required to use the scale in sponsored studies—that the C–SSRS, because of its navigation flaws and other issues, under-identifies many cases of suicidal ideation (type II error), misclassifies and/or over- identifies others (type I error), and misses other suicidality combinations entirely. There is also growing concern that the scale in its current format does not map to the updated FDA classification algorithm outlined in the FDA's 2012 Draft Guidance and is therefore becoming more of a liability than an asset. 22 PURPOSE OF THIS PAPER This paper extends the debate on the C–SSRS. Guided by Guilford's observation, articulated more than a half century ago, that rating categorizations need to be "well- defined, mutually exclusive, univocal and exhaustive," 23 we evaluate whether the C–SSRS adequately meets widely accepted psychometric standards. In doing so, we ask the following questions: 1) Is the C–SSRS comprehensive? Does it address the full spectrum of suicidal ideation and behavior and avoid type II errors (i.e., the danger of missing true suicidal phenomena)? 2) Is the scale consistent? Does it provide consistent instructions, definitions, and probes, mitigating against misclassification, including type I errors (i.e., the danger of false positives)? 3) Is the scale unambiguous? Are questions worded in such a way that they are not susceptible to multiple interpretations, mitigating against type I as well as type II errors? 4) To what extent does the C–SSRS map to the new 2012 FDA classification a lgorithm for suicide assessment (henceforth referred to as FDA- CASA 2012)? and 5) Is there consistency across all versions of the C–SSRS (a critical component to mapping to the FDA-CASA 2012 Draft Guidelines)? FINDINGS 1. Is the C–SSRS comprehensive? Does it address the full range of suicidal ideation and behavior? The first task in developing any scale is the definition of the construct. One part of this task is deciding how broadly the construct needs to be defined. Another part is how finely the construct should be divided. In principle, parsimony is preferable but not at the expense of ignoring the full range of phenomena that make up the construct. 24 In fact, generating a representative and comprehensive pool of items is considered a critical step in scale construction since, as Clark and Watson observe, "No existing data-analytic technique can remedy serious deficiencies in an item pool." 2 5 In the case of multidimensional phenomena, such as suicidal ideation and behavior, particular care needs to be taken to ensure that the scale encompass all dimensions to avoid the risk of under-identification of phenomena that could pose a deadly risk. Ideally a construct-valid measure needs to tap into all the dimensions of the construct without surplus characteristics that might contaminate it and should provide comprehensive coverage of the range of the construct. 26 Our most serious criticism of the C–SSRS in terms of scale acceptance is that it does not cover the full spectrum of suicidal ideation. As shown in Table 1, there are as many as 16 possible combinations of active suicidal ideation (defined in terms of the presence or absence of method, intent, and plan) and 32 combinations if passive ideation is considered as an additional factor. The C–SSRS, however, reduces this total number to four categories of active ideation and one category of p assive ideation and the null of all these (possible combination number 1), i.e., a total of six categories. This means that as many as 26 categories of suicidal ideation are overlooked. While the overlooked combinations may constitute 20 percent of all combinations of suicide ideation event phenomena, they can constitute 60 percent of a patient's time spent in suicidality, and often pose serious safety issues. 27,28 The S-STS/ISST-Plus/C–SSRS validation study, which mapped all three scales to the FDA-CASA 2012 categories, examined the extent of these missing combinations. 29 The results found that the C–SSRS categories did not capture combinations of suicidal ideation, method, intent, and plan that were detected in 67 percent of the subjects using the clinician-rated S- STS, 80 percent of the subjects using the patient-rated S-STS, and 76 percent of the subjects using the ISST-Plus. 29 Unlike the C–SSRS, the S-STS and the ISST-Plus map all 32 combinations as shown in Table 1. 2 9 Consider the patient who does not have current passive or active suicidal ideation but made a suicide plan some time ago and intends to carry out this plan at some point in the future. The patient has a plan with intent but without active or passive ideation (combination #11). Assume as well that the patient has never made a suicide attempt. This patient is likely to be at much more risk than someone without intent or plan, but there is no way of recognizing this risk on the C–SSRS because the patient's experience doesn't fit into any category. What about the person who has passive ideation, method, and intent but no plan (combination #23)? This patient's experience would not be recognized either. Even more serious perhaps is the patient who presents to the doctor with a command hallucination to

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