Leukocyte count and incidence of subarachnoid haemorrhage: a prospective cohort study.
BACKGROUND
Subarachnoid haemorrhage (SAH) is a devastating disease, in the majority of cases caused by a rupture of an arterial intracranial aneurysm. The effect of systemic low-grade inflammation on incidence of SAH is not known. The purpose of this study was to evaluate the relationship between leukocyte count, a marker of systemic inflammation, and incidence of SAH in a large cohort study.


METHODS
Leukocyte count and other cardiovascular risk factors were measured in 19,794 individuals (17,083 men and 2,711 women, mean age 44 years) participating in a health screening program between 1974 and 1981. Incidence of SAH in relation to baseline leukocyte concentration was studied during a mean follow-up of 27 years in participants free from previous stroke.


RESULTS
Ninety-five participants had a SAH, corresponding to an incidence of 22 per 100,000 in women and 17 per 100,000 in men. The hazard ratio for SAH per one standard deviation (2.01 × 10⁹ cells/L) increase of leukocyte concentration was 1.26 (95% CI 1.05-1.53, p = 0.014) after adjustment for several potential confounding factors including smoking. In sensitivity analysis, there was a significant association in smokers but not in non-smokers.


CONCLUSIONS
High leukocyte count at baseline was associated with increased incidence of SAH, although this relationship might be restricted to smokers. The results support the view that low-grade systemic inflammation could be involved in the pathogenesis of SAH, or constitute an early risk marker for the disease.
Cardiovascular Epidemiology Research Group, Department of Clinical Sciences Malmö, Lund University, CRC building 60 floor 13, Jan Waldenströms gata 35, 20502 Malmö, Sweden. martin.soderholm@med.lu.se.
Martin
M
Söderholm
Elisabet
E
Zia
Bo
B
Hedblad
Gunnar
G
Engström
D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007249:Inflammation / Q000097:blood / Q000150:complications*; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013345:Subarachnoid Hemorrhage / Q000097:blood / Q000150:complications* / Q000453:epidemiology*