Evaluation of patients with advanced cancer using the Karnofsky performance status.

The Karnofsky Performance Status Scale (KPS) was designed to measure the level of patient activity and medical care requirements. It is a general measure of patient independence and has been widely used as a general assessment of patient with cancer. Although there is a long history of use of the KPS for judging cancer patients, its reliability and validity have been assumed without formal investigation. The interrater reliability of the KPS was investigated in two ways, both of which gave evidence of moderately high reliability. The patients evaluated in their home were usually assigned a lower KPS score compared with a similar evaluation at the same time done in the outpatient clinic. Costruct validity of the KPS was demonstrated by strong correlation with several variables relating to physical function. On-study KPS score accurately predicted early death, but high initial KPS scores did not necessarily predict long survival. Patient deterioration with subsequent death within a few months could be predicted to a limited extent by a rapidly dropping KPS. These results suggest that the KPS has considerable validity as a global indicator of the functional status of patients with cancer and might be helpful for following other patients with chronic disease.