Non-somatic items on the PHQ-9 screening tool for depressive disorders can help identify patients with cancer at risk for major depressive disorder (MDD), according to research published in the Journal of Affective Disorders. Major depression is common in patients with cancer (11.1%), and researchers sought to determine the diagnostic accuracy of somatic vs cognitive-emotional PHQ-9 items.
Researchers collected routine data from 4705 patients who had been screened at the National Center for Tumor Diseases in Heidelberg, Germany. For diagnoses of MDD and any depressive disorder (ADD), researchers applied PHQ-9 items, receiver operating characteristics, sensitivity, specificity, positive and negative predictive values, the Youden Index, and the Clinical Utility Index.
The non-somatic items were critical to the diagnosis of MDD, while the diagnostic accuracy of the somatic items increased in the diagnosis of ADD. For both MDD and ADD, the non-somatic items “little interest” and “feeling down” had the best performance. Overall, the somatic items had less discriminatory value than the non-somatic items, but researchers advised they may be useful screening mechanisms for identifying patients with cancer who are at-risk and/or have mild or moderate depression.
The diagnoses were not validated by clinical interviews and there was only 1 self-reported instrument, which limited the study.
The clinical implications of the study include that the use of the PHQ-9, and especially the somatic items, is a useful and accurate screening mechanism for identifying patients with cancer who are at risk for MDD. This could prevent the underestimation of depressive syndromes in patients with cancer. In addition, clinicians should be trained not only to interpret and treat somatic symptoms, but also to identify potentially related depressive syndromes.
The researchers concluded that more research is necessary and noted, “Since the incidence of somatic symptoms can differ within cancer types…in a subsequent study we will investigate the diagnostic accuracy of the PHQ-9 items, depending on age, gender, and tumor disease.”
Grapp M, Terhoeven V, Nikendei C, Friederich HC, Maatouk I. Screening for depression in cancer patients using the PHQ-9: the accuracy of somatic compared to non-somatic items [published online May 13, 2019]. J Affect Disord. doi:10.1016/j.jad.2019.05.026