Objectives To investigate the longitudinal trends of decompressive craniectomy (DC) following traumatic brain injury (TBI) or stroke and explore whether the timing of cranial reconstruction affected revision or removal rates using Hospital Episode Statistics (HES) between 2014 and 2019.Design Retrospective observational cohort study using HES. The time frame definitions mirror those often used in clinical practice.Setting HES data from neurosurgical centres in England.Participants HES data related to decompressive craniectomy procedures and cranioplasty following TBI or stroke between 2014 and 2019.Main outcome measures The primary outcome was the timing and rate of revision/removal compared with cranioplasty within