Assessing agreement between salivary alpha amylase levels collected by passive drool and eluted filter paper in adolescents with cancer

Purpose/Objectives: To assess the validity of filter paper (FP) against the gold standard of passive drool (PD) for collecting salivary alpha amylase as a surrogate biomarker of psychological stress in adolescents with cancer. Design: Part of a longitudinal, descriptive study of symptoms in adolescents with cancer during chemotherapy. Setting: A pediatric hematology/oncology treatment center. Sample: 33 saliva sample pairs from nine adolescents with cancer, aged 13-18 years. Methods: Salivary alpha amylase was collected by PD and FP at four time points during a cycle of chemotherapy: days 1 (time 1) and 2 (time 2) of chemotherapy, day 7-10 (time 3), and day 1 of the next cycle (time 4). A random effects regression was used to assess the correlation between PD and FP values, and a Bland Altman analysis was conducted to assess agreement between the values. Main Research Variables: Salivary alpha amylase. Findings: The estimated correlation between PD and FP values was r = 0.91, p < 0.001. Regression results were also used to rescale FP values to the levels of the PD values because the FP values were on a different scale than the PD values. The Bland Altman analysis revealed that the agreement between the rescaled FP values and PD values was not satisfactory. Conclusions: Eluted FP may not be a valid method for collecting salivary alpha amylase in adolescents with cancer. Implications for Nursing: Psychological stress in adolescents with cancer may be linked to negative outcomes, such as greater symptom severity and post-traumatic stress disorder. Nurses need valid, efficient, biobehavioral measures to assess psychological stress in the clinical setting.