Testing the differential effects of symptom management interventions in cancer.

Objective: The purpose of this study was to test for moderating effects of patient characteristics on self-management interventions developed to address symptoms during cancer treatment. Patient's age, education, and depressive symptomatology were considered as potential moderators.

Methods: A secondary analysis of data of 782 patients from two randomized clinical trials was performed. Both trials enrolled patients with solid tumors undergoing chemotherapy. After completing baseline interviews, patients were randomized to a nurse-delivered intervention versus intervention delivered by a 'coach' in trial I and to a nurse-delivered intervention versus an intervention delivered by an automated voice response system in trial II. In each of the two trials, following a six-contact 8-week intervention, patients were interviewed at week 10 to assess the primary outcome of symptom severity.

Results: Although nurse-delivered intervention proved no better than the coach or automated system in lowering symptom severity, important differences in the intervention by age were found in both trials. Patients aged ≤45 years responded better to the coach or automated system, whereas those aged ≥75 years favored the nurse. Education and depressive symptomatology did not modify the intervention effects in either of the two trials. Depressive symptomatology had a significant main effect on symptom severity at week 10 in both trials (p = 0.03 and p < 0.01, respectively). Education was not associated with symptom severity over and above age and depressive symptomatology.

Conclusions: Clinicians need to carefully consider the age of the population when using or testing interventions to manage symptoms among cancer patients.