Performance of four diagnostic approaches to depression in adults with cancer

The potentially confounding influence of somatic symptoms in identifying depression in medically ill patients has long been of concern, resulting in several proposed alternative diagnostic approaches. These approaches have been compared in the cancer setting, but the strengths and weaknesses of the alternative approaches have rarely been examined. The purpose of the current study was to examine the performance of four approaches to depression assessment among ambulatory cancer patients.

Outpatients were recruited from a large cancer center (N = 611). Participants had to be 40 years or older, English-speaking, and have a cancer diagnosis. All participants completed a sociodemographic questionnaire and a modified Patient Health Questionnaire-9 with additional items targeting the Endicott and Cavanaugh substitutive criteria.

Depression prevalence varied significantly by diagnostic approach, with the inclusive approach identifying the largest proportion as depressed (9.3%, n = 57), followed by the Endicott-substitutive (6.2%, n = 38), exclusive (4.6%, n = 28), and Cavanaugh-substitutive approach (1.8%, n = 11). Somatic items were significantly elevated across all four approaches.

The inclusive approach that retains use of somatic symptoms is appropriate when screening cancer patients for depression. The fact that somatic symptoms were more prevalent across approaches suggests that they may not inflate the prevalence of depression as much as some have feared. Rather, somatic items may explain variance in depressive symptoms beyond that explained by the presence of cancer and its treatment. Additionally, the Endicott items appeared useful for capturing depressive symptoms that are not included in the existing DSM criteria, and may have a place in clinical and research settings.