Three sets of diagnostic criteria for major depression and correlations with serotonin-induced platelet calcium mobilization in cancer patients.

OBJECTIVE: Enhanced serotonin-induced platelet calcium mobilization has been proposed to be a biological marker for the pathophysiology of major depression in physically healthy patients. To determine the most appropriate method of diagnosing major depression in cancer patients, we compared serotonin-induced platelet calcium mobilization between patients with and without major depression diagnosed according to three different sets of diagnostic criteria (inclusive, substitutive and exclusive). METHODS: Among the cancer patients referred to our institution between June 1997 and March 1998, 24 patients diagnosed as having major depression according to the inclusive approach (in which the nine traditional symptoms of major depression contribute towards the diagnosis of depression regardless of its presumed etiology) participated in the study. Serotonininduced platelet calcium mobilization was examined in these patients and in the same number of non-depressed controls matched for age, sex, cancer stage and cancer site. The depressed patients were then re-evaluated using substitutive and exclusive criteria, and calcium mobilization comparisons with the relevant controls were repeated. RESULTS: Compared with the controls, an enhanced serotonin-induced platelet calcium response was only observed in the patients with major depression according to the exclusive criteria. No significant enhancement was observed when the inclusive or substitutive approaches were used. CONCLUSION: These findings, based on the use of enhanced serotonin-induced platelet calcium mobilization as a biological marker, suggest that the exclusive approach might be the most valid and appropriate method of diagnosing major depression in cancer patients, while the inclusive and substitutive approaches might overestimate the occurrence of major depression in these patients.