Intracerebral Hemorrhage In Southern Norway. A study of incidence and outcome
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Aims: We aimed to assess the incidence and baseline characteristics of first ever intracerebral hemorrhage (ICH) in Southern Norway leading to hospitalization, mortality rates after ICH and factors associated with 30-day mortality and long term mortality. We further aimed to assess clinical functioning including cognition in long term survivors and associations between baseline factors and 1) functional dependency and 2) cognitive impairment. We also aimed to assess the rate of recurrent ICH and late seizures.
Materials and methods: All consecutive patients hospitalized with a first-ever ICH in the period 2005-2009 in a well-defined area were identified. Risk factors, clinical-, and radiological data were recorded in a stroke register from September 2007 and retrieved from patient files in cases prior to that. In Paper I we calculated the crude incidence and the incidence adjusted to the standard European population. In paper II death registered up to December 31.2011 in the National Population Register was recorded and causes of death were obtained from Statistics Norway and patient files. The prognostic value of various baseline clinical and radiologic factors for 30-day and long term mortality was assessed. Information on recurrent ICH was obtained by review of patient files. In Paper III we did an extensive in person follow up of all long term survivors between August and November 2011. This included the National Institute of Health Stroke Scale (NIHSS), the modified Rankin Scale (mRS), the Barthel Index (BI) and the Montreal Cognitive Assessment (MoCA). Information on late seizures was obtained through the in person follow up and by review of patient files.
Results: Incidence (Paper I): We identified 134 patients, 74 (55%) men and 60 (45%) women with first ever ICH. The crude annual incidence rate per 100.000 per year was 19.6 for men, 15.7 for women and 17.6 for both sexes. Adjusted to the standard European population it was 16.9 for men, 8.8 for women (p<0.001) and 12.5 for both sexes. The overall age adjusted rate ratio men/women was 1.78 (p=0.001). Hematoma location was lobar in 36.6%, deep cerebral in 45.5%, cerebellar in 9.7%, and brain stem in 8.2%. Intraventricular hemorrhage occurred in 37%. The proportion with oral anticoagulant treatment associated ICH (OAT-ICH) was 26.9%.
Mortality (Paper I and II): Overall mortality at 2 days was 23%, at 7 days 30%, at 30 days 36.6%, at 1 year 46 % and at 2 years 53%. Factors independently associated with 30-day mortality were warfarin, Glasgow Coma Scale (GCS) score, intraventricular hemorrhage, and leukoaraiosis (LA) score. Factors independently associated with long term mortality in 30-day survivors were coronary heart disease (CHD), GCS score, and LA score. Median follow up time was 4.7 years.
Recurrent ICH (Paper II): Recurrent ICH was seen in 4 of 36 patients (11.1%) discharged alive after a lobar index ICH versus 0 of 52 (0%) after index ICH in other locations (p=0.025).
Clinical functioning in long term survivors (Paper III): Of 51 patients alive 50 (24 men and 26 women) had an in person follow up after a median of 3.8 years. Men were younger than women (70.4 versus 78.7 years, p=0.019). Forty one (82%) lived in their private homes and 9 (18%) in nursing homes, 34 (68%) were independent (mRS 0-2) and 16 (32%) were dependent (mRS 3-5). Factors independently associated with dependency were female sex and LA score. The proportion with cognitive impairment (MoCA≤23) was 61.4%. Factors independently associated with cognitive impairment were age and lobar ICH location.
Late seizures (not published): Late seizures occurred in 5 of 50 (10%) long term survivors; 5 of 19 (26%) with lobar ICH versus 0 of 31 (0%) with ICH in other locations (p=0.005). Patients with late seizures had larger median ICH volumes than patients without seizures, 39 ml (IQR 23.5- 58.5) versus 7 ml (IQR 2.5-16.5), p=0.004.
Conclusions: The incidence of first ever ICH in Southern Norway is in the mid range in Europe and lower than in the only prior Norwegian incidence study. Men are at higher risk than women. The proportion with OAT-ICH is higher than in most reports reflecting a well implemented use of warfarin in atrial fibrillation in the elderly (Paper I). LA is independently associated with both 30-day mortality and long term mortality in 30-day survivors. Warfarin is independently associated with 30-day mortality and coronary heart disease with long term mortality in 30-day survivors. Recurrent ICH is more frequent after lobar ICH than after ICH in other locations (Paper II). The majority of long term survivors live in their private homes. Two thirds are functionally independent. Dependency is associated with LA and female sex. Cognitive impairment is common and associated with lobar location of ICH (Paper III). Late seizures were associated with lobar index ICH and larger ICH volumes (not published).