Patient-Reported Functional Status in Outpatients With Advanced Cancer: Correlation With Physician-Reported Scores and Survival

Abstract

Context: Performance status measures are increasingly completed by patients in outpatient cancer settings, but are not well validated for this use.

Objectives: We assessed performance of a patient-reported functional status measure (PRFS, based on the Eastern Cooperative Oncology Group [ECOG]), compared with the physician-completed ECOG, in terms of agreement in ratings and prediction of survival.

Methods: Patients and physicians independently completed five-point PRFS (lay version of ECOG) and ECOG measures on first consultation at an oncology palliative care clinic. We assessed agreement between PRFS and ECOG using weighted Kappa statistics, and used linear regression to determine factors associated with the difference between PRFS and ECOG ratings. We used the Kaplan-Meier method to estimate the patients' median survival, categorized by PRFS and ECOG, and assessed predictive accuracy of these measures using the C-statistic.

Results: For the 949 patients, there was moderate agreement between PRFS and ECOG (weighted Kappa 0.32; 95% CI: 0.28-0.36). On average, patients' ratings of performance status were worse by 0.31 points (95% CI: 0.25-0.37, P < 0.0001); this tendency was greater for younger patients (P = 0.002) and those with worse symptoms (P < 0.0001). Both PRFS and ECOG scores correlated well with overall survival; the C-statistic was higher for the average of PRFS and ECOG scores (0.619) than when reported individually (0.596 and 0.604, respectively).

Conclusion: Patients tend to rate their performance status worse than physicians, particularly if they are younger or have greater symptom burden. Prognostic ability of performance status could be improved by using the average of patients and physician scores.

Keywords: Palliative care; cancer; patient-reported outcome measures; performance status; prognosis; survival.