Prognostic value of a patient-reported functional score versus physician-reported Karnofsky Performance Status Score in brain metastases

INTRODUCTION: Our aim was to investigate the added prognostic value of a patient-reported functional outcome score over Karnofsky Performance Status (KPS) in patients with non-small-cell lung cancers (NSCLC) with brain metastases. MATERIALS AND METHODS: The baseline data are from a prospective cohort study involving 140 consecutive patients presenting at our institute. A patient reported performance status (PRPS) was obtained by summing the physical- and role-functioning scale scores of the EORTC QLQ C30 questionnaire. Nested cox proportional hazards models predicting survival were developed including both KPS and PRPS (full model), KPS only (KPS Model), and PRPS only (PRPS model). The incremental value of the addition of KPS or PRPS was ascertained using the likelihood ratio test, model adequacy index and integrated discrimination Improvement (IDI). RESULTS: PRPS was an independent and statistically significant prognostic factor and had only a moderate degree of agreement with KPS. All models showed nearly the same discrimination and calibration accuracy, but the likelihood ratio test comparing the full model to the KPS model was significant (L.R. Chi(2) = 5.34, p = 0.02). Model adequacy index for the KPS model was 85% versus 95% for the PRPS model. IDI when comparing the KPS model to the full model was 0.0279, while it was 0.008 for the PRPS model versus the Full model. CONCLUSIONS: Use of patient-reported functional outcomes like PRPS can provide the same prognostic information as KPS in patients of NSCLC with brain metastases. HIGHLIGHTS: Patient-reported functional status (PRPS) has a moderate degree of agreement with KPS. PRPS is an independent and significant predictor of survival in brain metastases. PRPS can replace KPS without loss of prognostic information.