title: Stroke seasonality associations with subtype, etiology and laboratory results in the Ludwigshafen Stroke Study (LuSSt).
abstract: Data on seasonal differences in stroke incidence are conflicting. Little is known about seasonal variability in etiological stroke subtypes and population-based data on possible trigger factors are lacking. The Ludwigshafen Stroke Study is a prospective population-based stroke registry. All residents of the city of Ludwigshafen who suffer from acute stroke or TIA are registered. Patients with first-ever stroke (FES) were included for the present analysis. Between January 1, 2006 and December 31st, 2010, 1,779 patients (age 71.7 ± 13.4 years (mean + standard deviation; 897 (50.4 %) women) suffered a FES. Incidence for FES was lowest in summer (reference) with significantly higher rates in winter (rate ratio (RR) 1.20, 95 % confidence interval (CI) 1.05-1.37) and spring (RR 1.21 95 % CI 1.06-1.38). First-ever ischemic stroke (FEIS) was more common in winter (RR 1.16, 95 %CI 1.01-1.34) and first-ever intracerebral haemorrhage (FE-ICH) was more frequent in spring (RR 2.0, 95 %CI 1.24-3.22) than in summer. In FES, systolic and diastolic blood pressure on admission (SBP/DBP) showed significant variation with lowest values in summer (SBP: p = 0.02; DBP p = 0.05). In subtypes of FEIS, cardioembolism tended to be more common in winter (p = 0.14). There were no differences in risk factor prevalence between seasons. Leukocyte count on admission was lowest in summer (8.2 ± 1.4/μl) and highest in winter (8.9 ± 1.9/μl; p = 0.008). The hematocrit showed a similar trend (p = 0.06). Our data show higher incidence rates for FES in winter and spring, for FEIS in winter and for FE-ICH in spring. Variations in blood pressure on admission and leukocyte counts were associated with these findings and may possibly contribute to seasonal stroke variability.
authors: Department of Neurology, Städtisches Klinikum Ludwigshafen, Bremserstrasse 79, Ludwigshafen a. Rh., Germany. frederickpalm@gmx.de
authors: Frederick
authors: F
authors: Palm
authors: Michael
authors: M
authors: Dos Santos
authors: Christian
authors: C
authors: Urbanek
authors: Matthias
authors: M
authors: Greulich
authors: Kathrin
authors: K
authors: Zimmer
authors: Anton
authors: A
authors: Safer
authors: Armin Jürgen
authors: AJ
authors: Grau
authors: Heiko
authors: H
authors: Becher
mesh_terms: D000369:Aged, 80 and over; D015415:Biomarkers / Q000032:analysis*; D002097:C-Reactive Protein / Q000378:metabolism; D002543:Cerebral Hemorrhage / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D005858:Germany / Q000453:epidemiology; D006400:Hematocrit / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D002546:Ischemic Attack, Transient / Q000453:epidemiology / Q000209:etiology*; D007958:Leukocyte Count / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D015995:Prevalence; D012042:Registries; D012044:Regression Analysis; D012307:Risk Factors; D012621:Seasons; D020521:Stroke / Q000453:epidemiology / Q000209:etiology*
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein
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