External Validation of Risk Factors for Unplanned Hospitalization in Older Adults With Advanced Cancer Receiving Chemotherapy.

BACKGROUND: Older adults (age ≥65 years) receiving chemotherapy are at risk for hospitalization. Predictors of unplanned hospitalization among older adults receiving chemotherapy for cancer were recently published using data from a study conducted by the Cancer and Aging Research Group (CARG). Our study aimed to externally validate these predictors in an independent cohort including older adults with advanced cancer receiving chemotherapy. METHODS: This validation cohort included patients (n=369) from the GAP70+ trial usual care arm. Enrolled patients were aged ≥70 years with incurable cancer and were starting a new line of chemotherapy. Previously identified risk factors proposed by the CARG study were ≥3 comorbidities, albumin level <3.5 g/dL, creatinine clearance <60 mL/min, gastrointestinal cancer, ≥5 medications, requiring assistance with activities of daily activities (ADLs), and having someone available to take them to the doctor (ie, presence of social support). The primary outcome was unplanned hospitalization within 3 months of treatment initiation. Multivariable logistic regression was applied including the 7 identified risk factors. Discriminative ability of the fitted model was performed by calculating the area under the receiver operating characteristic (AUC) curve. RESULTS: Mean age of the cohort was 77 years, 45% of patients were women, and 29% experienced unplanned hospitalization within the first 3 months of treatment. The proportions of hospitalized patients with 0-3, 4-5, and 6-7 identified risk factors were 24%, 28%, and 47%, respectively (P=.04). Impaired ADLs (odds ratio, 1.76; 95% CI, 1.04-2.99) and albumin level <3.5 g/dL (odds ratio, 2.23; 95% CI, 1.37-3.62) were significantly associated with increased odds of unplanned hospitalization. The AUC of the model, including the 7 identified risk factors, was 0.65 (95% CI, 0.59-0.71). CONCLUSIONS: The presence of a higher number of risk factors was associated with increased odds of unplanned hospitalization. This association was largely driven by impairment in ADLs and low albumin level. Validated predictors of unplanned hospitalization can help with counseling and shared decision-making with patients and their caregivers. CLINICALTRIALS: gov identifier: NCT02054741.