What Is the Definition of Clinically Significant?

The DSM-5 and Diagnosing Clinically Significant Depression

Depression. Paul Gilham / Staff / Getty Images

When it comes to depression, clinical significance indicates behaviors and symptoms that are considered to be outside the range of normal, and are marked by distress and impairment of daily functioning.

When Is a Mood Disorder Clinically Significant?

The criteria for a mood disorder and its clinically significant symptoms are set by the Diagnostic and Statistical Manual of Mental Disorders (DSM). In the DSM-IV, published in 2000, "clinically significant distress and impairment” was added to the diagnosis criteria for all mental disorders.

The thinking went that the diagnostic criteria set forth in the previous DSM (DSM-III) was overly broad. By adding "clinically significant distress and impairment," it sought to narrow down diagnosis of various mental disorders to people who are not just showing symptoms, but whose symptoms are creating a serious problem in their lives. With the publication of the DSM-5 in 2013, the standards for clinical significance have carried over, although the editors have taken it a step further, adding severity measures. Through adding severity measures, the editors of the DSM-5 have fine-tuned the diagnostic criteria and linked it to treatment and outcomes. 

An example of the severity measures is the Patient Health Questionnaire (PHQ-9), which outlines nine criteria for major depressive disorder (at least five of the criteria must be met for a diagnosis of major depression). In terms of scoring, a score of five merits a diagnosis, but a score of ten is needed to define the depression as "clinically significant" and warranting treatment.

Another example is that of sadness in a child. For it to be considered clinically significant, the child would have had symptoms present for at least two weeks, on all or most days, and her sadness will have affected her interactions with family and friends and significantly interfered with her ability to attend school or complete school work.

What Causes Clinically Insignificant Depression?

If symptoms of depression are present, but the level of severity, persistence and impact of the symptoms doesn't meet the diagnostic criteria for clinically significant depression, it may be considered clinically insignificant. To go back to the example of the sad child, a child who does not show clinically significant depression might be experiencing temporary feelings of sadness that last for three to four days with no other symptoms of childhood depression present.

Clinical Significance in Treatment

When it comes to treatment, clinical significance reflects the size of the treatment effect. Clinical significance is a different concept than statistical significance, or the mathematical determination of an event, symptom, behavior, etc. not occurring merely by chance. 

While some statistically significant events may not be clinically relevant, clinically significant events may sometimes be statistically significant.

This is how clinical significance plays out in practice.

Clinicians use up-to-date research to inform their treatment and clinical judgment. A treatment that's research might yield statistically significant results, but if they're not clinically significant, the clinician is unlikely to incorporate the treatment into his practice.


Boris Birmaher, MD, David Brent, MD, et al.Practice Parameter for the Assessment and Treatment of Children and Adolescents With Depressive Disorders Journal of American Academy of Child and Adolescent Psychiatry. 46(11). November 2007. 1503-1526.

National Survey Confirms that Youth are Disproportionately Affected by Mental Disorders. National Institute on Mental Health. Accessed: March 24, 2011. http://www.nimh.nih.gov/science-news/2010/national-survey-confirms-that-youth-are-disproportionately-affected-by-mental-disorders.shtml

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