Long-term excess mortality after chronic subdural hematoma

Objective: To assess possible long-term excess mortality and causes of death of patients with chronic subdural hematoma (CSDH). Methods: A retrospective study (1990–2015) of adult patients (n = 1133, median age = 76 years old, men = 65%) with CSDH identified by ICD-codes and verified by medical records. All patients were followed until death or the end of 2017. Cumulative relative survival ratios and relative excess risks of death (RER) were estimated by comparing patients’ mortality with that in the entire regional matched population. The causes of death were compared with a separate reference group formed by randomly choosing sex, age, and calendar time matched controls (4 controls per each CSDH patient). Results: The median follow-up time was 4.8 years (range = 0–27 years), and 710 (63%) of the patients died (median age at death = 84 years old). The cumulative excess mortality was 1 year = 9%, 5 years = 18%, 10 years = 27%, 15 years = 37%, and 20 years = 48%. A subgroup of CSDH patients (n = 206) with no comorbidity had no excess mortality. Excess mortality was related to poor modified Rankin score at admission (RER = 4.93) and at discharge (RER = 8.31), alcohol abuse (RER = 4.47), warfarin (RER = 2.94), age ≥ 80 years old (RER = 1.83), non-operative treatment (RER = 1.56), and non-traumatic etiology (RER = 1.69). Hematoma characteristics or recurrence were unrelated to excess mortality. Dementia was the most common cause of death among the CSDH patients (21%) and the third most common cause in the reference group (15%, p < 0.001). Conclusions: Patients with CSDH have continuous excess mortality up to 20 years after diagnosis. Patient-related characteristics have a strong association with excess mortality, whereas specific CSDH-related findings do not. CSDH patients have an increased risk for dementia-related mortality.