Patient Performance Status
Performance status is a numerical rating given to a patient’s ability to function in daily life, including the ability to care for oneself, engage in physical activity, and whether any assistance or medical care is necessary for the patient. Performance status scales are widely used in assessing the expected outcome of cancer (or prognosis).1
What is performance status scoring?
David Karnofsky and his colleagues described the first performance status scoring in a textbook published in 1948. The Karnofsky scale uses a scale between 0 and 100. A score of 100 represents normal activity, and a score of 0 occurs at death.2
In 1960, the Eastern Co-operative Oncology Group (ECOG) simplified the scoring system to five points. It is sometimes referred to as the Zubrod scale because C. Gordon Zubrod was the principal researcher. Later, a sixth point was added, with 0 denoting someone who is fully active and 5 occurring at death. The ECOG performance status is often used in clinical trials when enrolling patients to help keep study populations consistent. The performance status is also used to evaluate patient’s ability to function as a result of cancer treatment.1-3
Several studies have determined that both the Karnofsky and ECOG performance status scores are reliable. Studies have also demonstrated a high level of agreement across different raters for both scoring systems.1,3,4
90: Able to carry on normal activity with minor signs or symptoms of disease
70: Able to care for self but unable to carry on normal activity or to do active work
50: Requires considerable assistance and frequent medical care
30: Severely disabled; hospitalization is appropriate although death is not imminent
10: Declining, approaching death
How do performance scores determine prognosis?
Performance status scores are often used to help determine prognosis for lung cancer. Several studies that used the Karnofsky performance scale have determined that predicting survival is valid only for patients with scores less than 50. At scores of 30-40, patients had a survival time of approximately 49.8 days, while patients with scores of 10-20 had survival of approximately 16.8 days.5
The ECOG performance status scores also provide prognostic estimates at the lower levels of functioning. A score of 3 on the ECOG scale correlates to a survival of approximately less than 3 months, while a score of 4 correlates to an approximate survival of less than 1 month.5