title: "MOONSTROKE": Lunar patterns of stroke occurrence combined with circadian and seasonal rhythmicity--A hospital based study.
abstract: Both time of the day and season have been shown to have a significant effect on stroke incidence. In contrast, the role played by the moon has been little studied. We aimed to investigate the potential association of the lunar phase with the incidence of stroke subtypes [intracerebral hemorrhage (ICH), transient ischemic attack (TIA) and ischemic stroke (IS)], adjusted by circadian and seasonal variations. Consecutive stroke admissions to the Royal Melbourne Hospital (RMH) were analyzed from 2004-2011. Of 6252 patients, 4085 (65.3%) had confirmed dates and hour of the day. Of these, 632 (15.5%) had ICH, 658 (16.1%) presented with TIA and 2202 (53.9%) had IS. There were also 593 (14.5%) stroke mimics. We measured the association of stroke incidence with a particular lunar phase using an incidence rate ratio (IRR) with 95% confidence intervals (CI) using Poisson regression model (new moon set as reference). Compared with new moon phase, ICHs occurred significantly more during the first quarter (IRR, 1.55; 95%CI, 1.04 to 2.30; p = 0.03). More TIAs were observed during the first quarter and full moon than in new moon (IRR, 1.69; 95%CI, 1.16 to 2.46; p = 0.01; IRR, 1.52; 95%CI, 0.00 to 2.31; p = 0.05; respectively). Both ICH and TIA occurrence slightly decreased as lunar illumination increased (IRR, 0.99; 95%CI, 0.99 to 1.00; p = 0.01; IRR, 0.99; 95%CI, 0.99 to 1.00; p = 0.04; respectively). No association was found between lunar phase or illumination and IS. All stroke subtypes were less likely to happen between 12AM and 6AM than the remaining 18 h of the day. IS occurrence was significantly higher during the spring than summer (IRR, 1.14; 95%CI, 1.02 to 1.28; p = 0.03). For the patients older than 65 years, incidence of both ICH and IS was higher in spring than in summer (IRR, 1.33; 95%CI, 1.01 to 1.74; p = 0.04; IRR, 1.22; 95%CI, 1.06 to 1.39; p = 0.005; respectively). The lunar phase and illumination are associated with both ICH and TIA incidence. These findings should be tested on other stroke databases.
authors.affiliation: a Melbourne Brain Centre, Royal Melbourne Hospital, University of Melbourne , Parkville , Australia .
authors.forename: Yiting
authors.initials: Y
authors.lastname: Mao
authors.forename: Yisrael
authors.initials: Y
authors.lastname: Schnytzer
authors.forename: Lucy
authors.initials: L
authors.lastname: Busija
authors.forename: Leonid
authors.initials: L
authors.lastname: Churilov
authors.forename: Stephen
authors.initials: S
authors.lastname: Davis
authors.forename: Bernard
authors.initials: B
authors.lastname: Yan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002543:Cerebral Hemorrhage / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D016009:Chi-Square Distribution; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D015994:Incidence; D002546:Ischemic Attack, Transient / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D016081:Moon; D016017:Odds Ratio; D010343:Patient Admission; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012621:Seasons; D020521:Stroke / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D013997:Time Factors; D014739:Victoria / Q000453:epidemiology
keywords: Circadian rhythms; intracerebral hemorrhage; ischemic stroke; lunar phase; seasonality; transient ischemic attack