High haemoglobin levels and mortality in males with intracerebral haemorrhage: a retrospective cohort study

OBJECTIVES: To examine the association between high haemoglobin levels and outcomes in intracerebral haemorrhage (ICH) in a multicentre cohort study. DESIGN: Prospective multicentre cohort study. SETTINGS: 21 tertiary hospitals across mainland China. PARTICIPANTS: A total of 5318 consecutive in-hospital spontaneous ICH patients were recruited between January 2012 and June 2016. PRIMARY AND SECONDARY OUTCOME MEASURES: Haemoglobin levels were measured on admission. Binary or ordinary logistic regression was used to evaluate the independent relationship of haemoglobin level with clinical outcomes at 3 months, measured as death or disability. Restricted cubic spline regression was fitted to examine the potential non-linear shape of the dose–response curve between the whole haemoglobin levels and 3-month poor outcomes. RESULTS: A total of 5031 patients with ICH were analysed (64.3% male; mean age (SD), 57.8 (15.2) years). We found that the highest haemoglobin quintile was associated with poor outcomes 3 months in males (adjusted OR (aOR) 1.65, 95% CI 1.21 to 2.25) but not in females, which was also observed in the pooled analysis of three subcohorts in male patients (average aOR 1.70, 95% CI 1.23 to 2.33). The spline regression suggested a non-linear association between haemoglobin levels and outcomes and a linear relationship was observed between an elevated haemoglobin level and 3-month disability/death in males (haemoglobin level per 10 g/L: aOR 1.24, 95% CI 1.10 to 1.40, p<0.001), which was mediated by larger haematoma volume (effect size: 0.115, 95% CI 0.012 to 0.231). CONCLUSIONS: This study found a sex-specific association between an elevated haemoglobin level and poor 3-month outcomes, which might be mediated by larger haematoma volume.