Patient Health Questionnaire 9 Validated for Depression Screening in Adolescents

Megan Brooks

November 01, 2010

November 1, 2010 — The Patient Health Questionnaire 9 (PHQ-9) has "high" sensitivity and "good" specificity for detecting major depression in adolescents in a primary care setting, new research, published online November 1 in Pediatrics, suggests.

The US Preventive Services Task force now recommends routine screening for depression among adolescents, but few screening instruments have been validated for use with adolescents in primary care settings.

"The PHQ-9 is widely used with adults but has never been validated among adolescents. In our work with adolescents, we found the tool to be very useful, and we felt that it was important to validate it in this age group," first study author Laura P. Richardson, MD, MPH, Seattle Children's Hospital Research Institute, Washington, told Medscape Medical News.

To that end, she and colleagues first had 2291 youth, 13 to 17 years old, complete a brief overall health survey, including the PHQ-2 item, which asks respondents how often they have experienced a depressed mood and/or lack of pleasure in usual activities in the past 2 weeks. A total of 281 youth (12%) screened positive for depression with a PHQ-2 score of 3 or higher.

They then invited 499 youth (271 depressed) to complete the PHQ-9 and 444 did; 242 of them were depressed based on the PHQ-2. Two youth who met criteria for bereavement were excluded, leaving 442 for the final analysis; 60% were female, 71% were white, 78% came from 2-parent households, and 87% came from households in which at least 1 parent had at least some college.

High False-Positive Rate

According to the investigators, among the 242 youth who had a positive PHQ-2 result on initial screening, 112 (46.2%) still had positive results on a second PHQ-2 performed 2 weeks later and 101 (41.7%) had positive results on the PHQ-9. Among the 202 who screened negative initially on the PHQ-2, 194 (96.0%) still had negative results on the second PHQ-2 and 190 (94.0%) screened negative on the PHQ-9, having a score of less than 11.

A PHQ-9 score of 11 or higher was the optimal cut point for maximizing sensitivity of the PHQ-9 without loss of specificity, the investigators report. At this cut point, the PHQ-9 had a sensitivity of 89.5% and a specificity of 77.5% for detecting youth who met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), criteria for major depression on the Diagnostic Interview Schedule for Children (DISC-IV).

In adults, a PHQ-9 score of 10 or higher is recommended to identify individuals with likely depression, the study authors note. Bruce Arroll, PhD, MBChB, of the Department of General Practice and Primary Health Care, Auckland University, New Zealand, says the cut point difference (≥10 for adults vs ≥11 for children) "may be due to the gold standard they used (the DISC-IV) or the population or just chance."

Earlier this year, Dr. Arroll, who was not involved in the current study, published results of a large validation study of the PHQ-2 and PHQ-9 to screen for major depression in an adult primary care population.

Dr. Richardson and colleagues point out in their article that the sensitivity of the PHQ-9 is higher in adolescents (compared with adults) but the specificity is lower, which suggests that it is less likely to miss youth with major depression but there is a higher false-positive rate.

The higher false-positive rate in adolescents, they suggest, may be due to a high rate of subthreshold depressive symptoms and adjustment disorders, as well as significant overlap of symptoms between mental health disorders among this age group.

"Reasonable Strategy"

"The PHQ-9 is free, easy to administer, and easy to score and interpret," Dr. Richardson told Medscape Medical News, "and in this study it performed well in identifying adolescents with major depression and had good validity in this age group."

For providers wanting to implement adolescent depression screening, her team suggests using the PHQ-2, which contains the first 2 items of the PHQ-9, and, for positive screens, moving on to the PHQ-9.

"This is a reasonable strategy," Dr. Arroll told Medscape Medical News. He made the point, however, that the Beck Depression Inventory "has better validity so in that sense the PHQ-9 is not as good."

The study authors and Dr. Arroll have disclosed no relevant financial relationships.

Pediatrics. Published online November 1, 2010.

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