The palliative performance scale: examining its inter-rater reliability in an outpatient palliative radiation oncology clinic.

Introduction: The Palliative Performance Scale (PPS) was developed by the Victoria Hospice Society in 1996 to modernize the Karnofsky Performance Scale. Currently, it is being used to measure palliative patient performance status in a variety of settings. Despite its widespread use, only one study has examined the inter-rater reliability of the PPS.
Purpose: To examine the inter-rater reliability of the PPS in measuring performance status in patients seen in an outpatient palliative radiation oncology clinic
Methods: Performance status for 102 consecutive patients was assessed by an oncologist (MD), a radiation therapist (RT), and a research assistant (RA) in the Rapid Response Radiotherapy Program at the Odette Cancer Centre in Toronto, Ontario, Canada. Raters' scores were analyzed for correlation and compared to evaluate the inter-rater reliability of the PPS tool.
Results: Excellent correlation was found between the scores rated by the MD and RA (r = 0.86); good correlation was observed between scores rated by the MD and RT (r = 0.69) and the RT and RA (r = 0.77). Scores between all three raters, as well as between rater pairs, were also found to have good reliability as measured by the Chronbach's alpha coefficient. Significant results were obtained for the range of PPS scores in which the majority of our patients fell: 40-80%.
Conclusion: PPS was shown to have good overall inter-rater reliability in an outpatient palliative setting, but more research is needed to establish the validity and reliability of the tool in a variety of different palliative settings.