Two-Item and Nine-Item Screening Tests May Be Useful to Detect Major Depression

July 22, 2010 — Two-item and nine-item screening tests may be useful to detect major depression, according to the results of a large validation study reported in the July/August issue of Annals of Family Medicine.

"Although screening for unipolar depression is controversial, it is potentially an efficient way to find undetected cases and improve diagnostic acumen," write Bruce Arroll, MBChB, PhD, from the Department of General Practice & Primary Health Care in Auckland, New Zealand, and colleagues. "Using a reference standard, we aimed to validate the 2- and 9-question Patient Health Questionnaires (PHQ-2 and PHQ-9) in primary care settings. The PHQ-2 comprises the first 2 questions of the PHQ-9."

At Auckland family practices, 2642 consecutive adult patients completed the PHQ-9 and then completed the Composite International Diagnostic Interview as a reference standard for depression. The investigators determined sensitivity and specificity of the PHQ-2 and the PHQ-9 for diagnosing major depression.

For a score of 2 or higher on the PHQ-2, sensitivity was 86% and specificity was 78%. For a score of 3 or higher, values were 61% and 92%, respectively. A score of 2 or higher on the PHQ-2 identified more cases of depression than a score of 3 or higher.

For a score of 10 or higher on the PHQ-9, sensitivity was 74% and specificity was 91%. Use of this cutoff point detected more cases of major depression than the PHQ scoring for major depression initially described by the original authors of this test in 1999.

"The PHQ-2 score of 2 or higher had good sensitivity but poor specificity in detecting major depression," the study authors write. "Using a PHQ-2 threshold score of 2 or higher rather than 3 or higher resulted in more depressed patients being correctly identified. A PHQ-9 score of 10 or higher appears to detect more depressed patients than the originally described PHQ-9 scoring for major depression."

A limitation of this study is possible lack of generalizability to primary care settings other than in New Zealand.

"For clinicians who wish to screen their patients for depression, we suggest they ask patients to respond to the first 2 questions of the PHQ-9 (ie, the PHQ-2); if their score is positive (if they score 2 or more), the patients should then complete the PHQ-9," the study authors conclude. "....A reevaluation of the original PHQ-9 criteria for major depression may also be needed, as the simple additive score PHQ-9 of 10 or higher identified more patients with depression than the originally described (and more time-consuming) method for scoring the PHQ-9."

The Health Research Council of New Zealand supported this study. The study authors have disclosed no relevant financial relationships.