Thursday, February 25, 2010

Is the Clinical Significance Criterion Significant?

The draft version of DSM-V: Revenge of the Fallen has been online for a few weeks (1) and much has already been written about it (1, 2, 3, 4). Much focus has been on what is "new" and what is "gone." One feature that is shared by the majority of DSM diagnoses, the "clinical significance" criterion, might be on its way out. Typically this criterion reads "The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning." The general rule being, if the person does not satisfy this criterion, a diagnosis probably should not be made.

This criterion is unique to the DSM-IV and is not found in the earlier versions of the text. The stated reason for adding it to the DSM was to
"establish the threshold for the diagnosis of a disorder in those situations in which the symptomatic presentation by itself (particularly in its milder forms) is not inherently pathological and may be encountered in individuals for whom a diagnosis of mental disorder would be inappropriate."  
Since mental health disorders are made by subjective analysis (often referred to as clinical judgment), does the addition of this criterion aid in the diagnostic process?

Not according to Wakefield et. al who published an article in the January 2010 issue of the American Journal of Psychiatry (5). In the article, titled, "Does the DSM-IV Clinical Significance Criterion for Major Depression Reduce False Positives? Evidence From the National Comorbidity Survey Replication," the authors' reason why the criterion is ineffective, is because it is redundant.

Wakefield argues that "distress is common to both normal reactions (e.g., acute grief) and disordered conditions, 'since most of these symptoms are either intrinsically distressing or are almost invariably accompanied by distress about having the symptom."

In other words, it's highly unlikely that an individual will satisfy full diagnostic criteria for a disorder and not be distressed or impaired.

(Click to Enlarge)

In the results reproduced above, out 2,071 respondents who reported episodes of sadness, 1,254 (60.5%) met diagnostic criteria for major depressive disorder (MDD). Of those who did not meet full criteria for MDD (n=817 or 39.5%), 93.5% did satisfy the "clinically significant distress or impairment" criterion. This suggests that the criterion is a poor indicator of diagnostic status. This result agrees with other research (6). 

It's unlikely that any modification of this criterion, other than its deletion, will resolve this issue of redundancy. If the definition is narrowed, there will be more false negatives; if the definition is broadened, there will be more false positives. Actually, the whole idea of false negatives/positives for already highly arbitrary (i.e. not valid) diagnoses is quite humorous, but I digress...

Wakefield, J., Schmitz, M., & Baer, J. (2010). Does the DSM-IV Clinical Significance Criterion for Major Depression Reduce False Positives? Evidence From the National Comorbidity Survey Replication American Journal of Psychiatry DOI: 10.1176/appi.ajp.2009.09040553

1 comment:

Neuroskeptic said...

The "clinical significance" criterion has always seems dubious to me because it doesn't specify what that means. So it's essentially redundant because it could mean anything.

Maybe there could be a more operationalized definition e.g. "Have you had to, or been advised to, take time off work" or something like that. Which has its own problems, but is at least meaningful...