Non-surgical patient characteristics best predict outcome after 6 months in patients surgically treated for chronic subdural haematoma

Abstract

Background: Chronic subdural haematoma (CSDH) is one of the most common conditions encountered in neurosurgical practice. After surgery, the patients often improve dramatically; but their long-term outcome is more uncertain. The purpose of this study was to investigate predictors of outcome 6 months after surgery.

Methods: Retrospective data were collected on patients in Orebro County, Sweden, who had undergone surgery for CSDH at the Orebro University Hospital between 2013 and 2019. The outcomes were defined as favourable or unfavourable in terms of the modified Rankin Scale (mRS). A favourable outcome was defined as either mRS 0-2 or an unchanged mRS score in patients scoring 3-5 before surgery. From the variables in the data collected, a multiple logistic regression model was constructed.

Results: The study comprised 180 patients, of whom 134 (74.4%) were male. Median age was 79.2 years (IQR 71.7-85.5), and 129 (71.7%) patients had a favourable outcome at 6 months. In the group with an unfavourable outcome, 18 (10%) had died and 33 (18.3%) had either lost their independence in daily living or become somewhat less independent. The final multiple logistic regression model consisted of pre-surgery variables only: age (OR 0.92, 95% CI 0.87-0.97), CRP (OR 0.96, 95% CI 0.94-0.99), GCS > 13 (OR 3.66, 95% CI 1.09-12.3), Hb (OR 1.03, 95% CI 1.00-1.05), and ASA score < 3 (OR 2.58, 95% CI 0.98-6.79). The whole model had an AUC of 0.88.

Conclusion: CSDH requiring surgery is associated with high morbidity and mortality at 6 months after surgery. Age, CRP, GCS, Hb and ASA score on admission for surgery are the variables that best predicts outcome. This knowledge can help to identify the patients at greatest risk for an unfavourable outcome, who may need additional support from the health care system.

Unstructured abstract: Chronic subdural haematoma (CSDH) is one of the most common conditions encountered in neurosurgical practice. After surgery, the patients often improve dramatically; but their long-term outcome is more uncertain. The purpose of this study was to investigate predictors of outcome, in terms of the modified Rankin Scale (mRS), 6 months after surgery. The study comprised 180 patients, of whom 134 (74.4%) were male. Median age was 79.2 years (IQR 71.7-85.5), and 129 (71.7%) patients had a favourable outcome at 6 months. In the group with an unfavourable outcome, 18 (10%) had died and 33 (18.3%) had either lost their independence in daily living or become somewhat less independent. The final multiple logistic regression model consisted of pre-surgery variables only: age (OR 0.92, 95% CI 0.87-0.97), CRP (OR 0.96, 95% CI 0.94-0.99), GCS > 13 (OR 3.66, 95% CI 1.09-12.3), Hb (OR 1.03, 95% CI 1.00-1.05), and ASA score < 3 (OR 2.58, 95% CI 0.98-6.79). The whole model had an AUC of 0.88. In conclusion, CSDH requiring surgery is associated with high morbidity and mortality at 6 months after surgery. Age, CRP, GCS, Hb and ASA score on admission for surgery are the variables that best predicts outcome. This knowledge can help to identify the patients at greatest risk for an unfavourable outcome, who may need additional support from the health care system.

Keywords: American Society of Anaesthesiologists’ (ASA) physical status classification; C-reactive protein (CRP); Chronic subdural haematoma (CSDH); Glasgow Coma Scale (GCS); Haemoglobin (Hb); Modified Rankin Scale (mRS).