Poster Presentation COSA 2015 ASM

A PILOT STUDY TO ASSESS VALIDITY OF THE DASS-21SUBSCALES IN AN OUTPATIENT ONCOLOGY POPULATION (#202)

Claire E Johnson 1 , Jade Newton 2 , Kellie S Bennett 3 , Joseph McTigue 1 , Scott Taylor 1 , Peter Lau 4 5
  1. School of Surgery, The University of Western Australia, Perth, Western Australia, Australia
  2. School of Population Health, School of Surgery, The University of Western Australia, Perth, Western Australia, Australia
  3. School of Psychiatry and Clinical Neurosciences, The University of Western Australia, Perth, Western Australia, Australia
  4. Cancer Medicine, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
  5. Department of Health Western Australia, Perth,, Western Australia, Australia

Aims
Depression and anxiety are common but often under-recognised comorbidities of oncology patients. The Depression, Anxiety and Stress Scale, short version (DASS-21) is a widely used psychological screening tool but is yet to be validated in an oncology population. We conducted a pilot study to validate the DASS-21 and explore its clinical utility for assessing the emotional status of oncology outpatients receiving chemotherapy.
Methods
Patients completed a survey, which included the DASS-21 questionnaire, while receiving chemotherapy in the oncology outpatient clinic at three tertiary hospitals in Perth. Exploratory factor analysis using Principal Axis Factoring was performed to investigate the internal structure of each sub-scale.
Results
Of 694 eligible patients, there were 364/432 (84%) respondents who completed all DASS-21 items.
A forced three-factor model resulted in most of the Depression and Stress items loading onto their respective factors, but the third factor primarily comprised four items previously considered somatic expressions of anxiety from the Anxiety scale (Factor loadings >0.3). Reliability for these scales was good (Chronbach’s alpha .88, .79 and .87 respectively).
A second analysis allowing items to empirically load onto factors resulted in four factors. The stress subscale loaded as expected onto factor one (Labelled ‘Stress’), however depression items relating to self-worth and cognitive anxiety items loaded onto factor two (‘Emotional Anxiety’), the remaining depression items loaded onto factor three (‘Depression’), and physiological anxiety items loaded onto the remaining factor (‘Physiological Anxiety’). Scale reliability was variable (Chronbach’s alpha: Stress .87, Depression .83, Emotional Anxiety .85, Physiological Anxiety .67).
Age, Karnofsky Status, disease, and treatment variables did not alter the way each item loaded onto the four factors.
Conclusions
Given the physical symptoms of people diagnosed with cancer and potential treatment side-effects, the DASS-21 three scale model should be used with caution if making inferences relating to the Anxiety subscale.