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.