External validation of the number of risk factors score in a palliative care outpatient clinic at a comprehensive cancer center.

Abstract

Prognostic tools are available to predict if terminally ill cancer patients have days or weeks to live. Tools for predicting the prognosis in ambulatory patients at an earlier stage are lacking. The Number of Risk Factors (NRF) score developed in ambulatory cancer patients receiving palliative radiation therapy may be suitable for this purpose but has not been tested in a palliative care setting. Our aim was to evaluate the prognostic accuracy of the NRF score in patients referred to a palliative care outpatient clinic at a comprehensive cancer center. We conducted a retrospective chart review of NRF scores and survival in 300 consecutive, newly referred patients. Measurements included primary cancer type, extent of disease, Karnofsky Performance Scale (KPS) score, and survival duration after first visit. One point was allocated each for cancer other than breast cancer, metastases other than bone, and low KPS score. Of 300 patients, 236 (79%) had advanced disease. Of those 236, 212 (90%) had a cancer other than breast cancer, 180 (76%) had metastatic disease in sites other than bone, and 64 (27%) had a KPS score <70%. During the 2-year follow-up, 221 (94%) patients died, with overall median survival of 4.9 months (95% confidence interval, 3.9-6.1 months). NRF scores of 0 to 1, 2, and 3 split the sample into subgroups with highly significantly different survival among the groups, with medians 9.0, 4.6, and 2.1 months, respectively (Wilcoxon test χ(2)=43.9, degrees of freedom [df] 2, p<0.0001). A simple parametric model was fit to determine the probability of subgroup members surviving to a certain number of months. In cancer patients referred to palliative care earlier in their disease trajectory, the NRF score may be a useful prognostic tool. Further validation in other palliative care populations is needed.