In Reply We thank Skelin and colleagues for their comments regarding our study1 evaluating the association of early palliative care with survival among patients with advanced lung cancer. Performance status is an important parameter in cancer treatment decision-making, and the Eastern Cooperative Oncology Group scale is one set of criteria used to encourage standardized reporting of treatment toxic effects and response, especially in the conduct of randomized clinical trials. Unfortunately, interrater reliability is inconsistent,2 inherent clinician bias may contribute to inconsistencies,3 and missing values are common in administrative data. Instead, we included the Charlson Comorbidity Index score, which measures comorbidities, and the Functional Comorbidity Index score, which measures physical function to predict survival in modeling, as surrogates of performance status because both are well validated in administrative data. Ultimately, treatment decision-making in oncology is complex, multifactorial, and influenced by clinician-related and patient-related factors; therefore, no single measure of patient suitability for treatment is likely to be sufficient.