The utility of the short version of the Depression Anxiety Stress Scales (DASS-21) in elderly patients with persistent pain: does age make a difference?

OBJECTIVE This study examined the assessment of the negative emotional constructs of depression, anxiety and stress with the short version (21 items) of the Depression Anxiety Stress Scales (DASS-21) in elderly patients (age > 60 years) with persistent pain. DESIGN A convenience sample of 2,045 patients attending a tertiary referral pain centre were categorized by age and included a group aged 60 years and under (n=1,245) for assessment of age differences. Elderly patients (n=800) were divided into 3 groups: 61-70 years (n=366), 71-80 years (n=308) and 81 years and over (n=126). Patients completed the DASS-21 as part of an initial clinical assessment process. RESULTS The failure rate for scale completion increased across age groups and was significantly higher in the oldest group compared to the youngest group. All scales demonstrated reasonable convergent and divergent validity. Confirmatory factor analysis confirmed a three-factor structure and is consistent with previous studies. Age differences in depression, anxiety and stress scores were also assessed. Interestingly, patients aged 60 years and under had significantly higher Depression and Stress scores compared to all other age groups. This group also had significantly higher Anxiety scores compared to patients aged 61-70 years. CONCLUSIONS Overall, the DASS-21 is a reliable and valid measure of depression, anxiety and stress in elderly patients with persistent pain. There are some age differences in the normative values for the reporting of mood symptoms and these need to be taken into account when assessing pain-related mood disturbance in older populations.