External validation and updating of prediction models for estimating the 1-year risk of low health-related quality of life in colorectal cancer survivors

Timely identification of colorectal cancer (CRC) survivors at risk of experiencing low health-related quality of life (HRQoL) in the near future is important for enabling appropriately tailored preventive actions. We previously developed and internally validated risk prediction models to estimate the 1-year risk of low HRQoL in long-term CRC survivors. In this article, we aim to externally validate and update these models in a population of short-term CRC survivors. In a pooled cohort of 1,596 CRC survivors, seven HRQoL domains (global QoL, cognitive/emotional/physical/role/social functioning, and fatigue) were measured prospectively at approximately 5 months postdiagnosis (baseline for prediction) and approximately 1 year later by a validated patient-reported outcome measure (European Organization for Research and Treatment of Cancer Quality of life Questionnaire–Core 30). For each HRQoL domain, 1-year scores were dichotomized into low vs. normal/high HRQoL. Performance of the previously developed multivariable logistic prediction models was evaluated (calibration and discrimination). Models were updated to create a more parsimonious predictor set for all HRQoL domains. Updated models showed good calibration and discrimination (AUC ≥0.75), containing a single set of 15 predictors, including nonmodifiable (age, sex, education, time since diagnosis, chemotherapy, radiotherapy, stoma, and comorbidities) and modifiable predictors (body mass index, physical activity, smoking, anxiety/depression, and baseline fatigue and HRQoL domain scores). Externally validated and updated prediction models performed well for estimating the 1-year risk of low HRQoL in CRC survivors within 6 months postdiagnosis. The impact of implementing the models in oncology practice to improve HRQoL outcomes in CRC survivors needs to be evaluated.