Climatological variations in daily hospital admissions for acute coronary syndromes Demosthenes B. Panagiotakos a, * , Christina Chrysohoou a , Christos Pitsavos a , Panagiotis Nastos b , Aggelos Anadiotis a , Constantinos Tentolouris a , Christodoulos Stefanadis a , Pavlos Toutouzas a , Athanasios Paliatsos c a Department of Cardiology, School of Medicine, University of Athens, 48–50 Chiou st, Glyfada, 165-61 Athens, Greece b Department of Geology, School of Science, University of Athens, Athens, Greece c Department of Mathematics, Technological Educational Institute of Piraeus, Piraeus, Greece Received 13 December 2002; accepted 2 April 2003 Abstract Objective: We examined the association between climatologic parameters and daily admissions for non-fatal acute coronary syndromes (ACS) to emergency units of hospitals in the greater Athens area, from January 2001 to August 2002. Methods: Daily mean, maximum and minimum temperatures, relative humidity, wind speed, barometric pressure and a thermo-hydrological index (T.H.I.) were measured at the meteorological station of the Laboratory of Climatology of the Geology Department of the University of Athens. In addition, the daily number of admissions for acute myocardial infarction or unstable angina in the five major general hospitals in the greater Athens area was recorded. Generalized additive models (GAM) were applied to regress-time-series of daily numbers of outpatients with acute cardiac events against climatological variations, after controlling for possible confounders and adjustment for over dispersion and serial correlation. Results: Five thousand four hundred fifty-eight Athenians with non-fatal acute cardiac events were admitted to the selected hospitals during the period of the study, 4093 (75%) males and 1365 (25%) females. There was a negative correlation between hospital admissions and mean daily temperature (MDT) with a 1 jC decrease in mean air temperature yielding a 5% increase in hospital admissions ( P < 0.05). This association was stronger in females and the elderly ( P < 0.01). Relative humidity was positively correlated with hospital admissions ( P < 0.05). Conclusion: Despite the relatively short study period ( < 2 years), these findings suggest a significant association between cold weather and increased coronary heart disease incidence, especially in the elderly and females. D 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Climatologic parameters; Daily admissions; Acute coronary syndromes 1. Introduction Hippocrates (430 BC), in his treatise ‘‘Of Airs, Waters and Places’’, pointed out that environmental conditions play a role in the pathogenesis of disease. In recent years, several studies indicated that variations in ambient temperature correlated with mortality and morbidity rates [1–9]. In general, increased death rates occur principally in the elderly [1,2], with the lowest death rates occurring on days of moderate temperature and highest rates at either end of the temperature range [10]. However, the strength of the associ- ation as well as the potential mechanisms to explain the association between climatological variations and human health is still under investigation, with both physiological and psychological mechanisms being suggested. We examined the relationship between climatological indices (average, maximum and minimum daily temperature, relative humidity, wind speed, and barometric pressure) and admissions due to non-fatal acute coronary syndromes (ACS) in cardiology emergency units in the greater Athens area. 2. Methods 2.1. Study population Between 1 January 2001 and 31 August 2002 we obtained the daily counts of admissions for non-fatal ACS 0167-5273/$ - see front matter D 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2003.04.050 * Corresponding author. Demosthenes Panagiotakos, 46 Paleon Polemiston st, 166 74 Glyfada Greece. Tel.: +30-109-603-116; fax: +30- 109-600-719. E-mail address: d.b.panagiotakos@usa.net (D.B. Panagiotakos). www.elsevier.com/locate/ijcard International Journal of Cardiology 94 (2004) 229 – 233