Puerto Rico Recurrence Scale: Predicting chronic subdural hematoma recurrence risk after initial surgical drainage

Background: Chronic subdural hematoma (CSDH) commonly affects older individuals and is associated with a relatively high rate of recurrence after surgery. Many studies have created grading systems to identify patients at high risk of CSDH recurrence after the initial surgery. However, no system has been adopted widely. The authors present the first CSDH grading system created from a population-based single-center data set. Methods: A single-center Puerto Rican population-based retrospective analysis was performed on consecutive patients treated for a CSDH at a designated institution from July 1, 2017 to December 31, 2019. Univariate and multivariate analyses were used to create a CSDH recurrence grading scale. Retrospective validation was conducted on this sample population. Results: The study included 428 patients. Preoperative midline shift, postoperative midline shift, and size of postoperative subdural space differed between the recurrence and nonrecurrence groups (P = 0.03, 0.002, and 0.002, respectively). A multivariate analysis was used to create a 10-point grading scale comprising four independent variables. Recurrence rates progressively increased from the low-risk (0-3 points) to high-risk (8-10 points) groups (2.9% vs. 20.3%; P < 0.001). Conclusion: A 10-point grading scale for CSDH recurrence was developed with four components: preoperative midline shift (≤1 and >1 cm), laterality (bilateral, unilateral-right, and unilateral-left), size of postoperative subdural space (≤1.6 and >1.6 cm), and pneumocephalus (present or absent). Patients who scored higher on the scale had a higher risk of recurrence. This CSDH grading scale has implications for Puerto Rico and the general population as the elderly population increases worldwide.