van der Gaag WH, Chiarotto A, Heymans MW, et al. - Researchers aimed at developing and internally validating three clinical prediction models for nonrecovery in older patients with back pain. In this prospective cohort study conducted in general practice (Back Complaints in the Elders, Netherlands), a total of 675 patients > 55 years with a new episode of care for back pain were included. Combining 6-month and 12-month follow-up data, they used three definitions of nonrecovery: (1) persistent back pain, (2) persistent disability, and (3) perceived nonrecovery. Using multivariable logistic regression, the models were developed (backward selection procedure). Internal validation of the models was done in 250 bootstrapped samples to correct for overoptimism. During development as well as internal validation, overall good performance was recorded for all 3 models. Following were the common predictors in all models: age, chronic duration, disability, a recent back pain episode, and patients' recovery expectations. Two of 3 models included spinal morning stiffness and pain during spinal rotation. The model predicting persistent disability showed best performance, displaying good calibration, discrimination, and explained variance .