Seasonal variation in cardiovascular and cerebrovascular hospitalizations across climatic zones in Northern and Southern Israel

Abstract Background Seasonal variation in cardiovascular and cerebrovascular diseases (CCD) is well documented, with higher morbidity in winter. Israel’s contrasting climates—Mediterranean in the north and semi-arid in the south—offer a unique setting to examine associations between seasonality and hospitalizations. Methods We conducted a 19-year retrospective ecological study using daily hospitalization data from Rambam Medical Center (RMC, north) and Soroka Medical Center (SMC, south) between 2000 and 2018. Hospitalizations were classified as acute myocardial infarction (AMI; ICD-9 410.0–410.9), ischemic stroke (ICD-9 434.90–434.91), or hemorrhagic stroke (ICD-9 430–431). Trend-Harmonic (Cosinor) analysis with Poisson or Negative Binomial regression models was applied to assess seasonal and weekly patterns. Results A total of 88,101 hospitalizations were analyzed (RMC: 42,971; SMC: 45,130). AMI admissions showed significant winter peaks at both centers (RMC IRR = 1.107, p < 0.001; SMC IRR = 1.145, p = 0.002) and summer declines (RMC IRR = 0.946, p = 0.010). Ischemic stroke showed a modest winter increase in the north (IRR = 1.046, p = 0.023), while hemorrhagic stroke showed no significant seasonal variation. Daily mean AMI hospitalizations were highest in winter (3.2 at RMC; 5.1 at SMC) and lowest in summer (2.7 at RMC; 4.0 at SMC). Conclusions AMI hospitalizations in Israel consistently peak in winter across diverse climates, highlighting robust seasonal associations in cardiovascular morbidity. These findings support targeted preventive strategies, including public health interventions and hospital preparedness, during colder months.