The relationship between meteorological conditions and index acute coronary events in a global clinical trial

Abstract

Background: Considerable uncertainty exists concerning the interaction between climate and human health. We explored this issue by evaluating the relationship between meteorological events and acute coronary syndrome (ACS) events.

Methods: 9406 patients in 29 countries at 440 Early versus Delayed, Provisional Eptifibatide in Acute Coronary Syndromes (EARLY ACS) clinical trial sites were linked to a weather station by location. Temperature, barometric pressure, precipitation, wind speed and combined temperature and relative humidity were normalized by location for the 37 days prior to the index ACS event that precipitated study enrollment. A meteorological event was defined as a change in any weather metric that was expected to occur in less than 10% of the exposure intervals: four separate 48-hour intervals within the seven days prior to an ACS event (T1, day of event and -1 day; T2, -2 to -3 days; T3, -4 to -5 days; and T4, -6 to -7 days). Results are reported as ratio of observed to expected events for the meteorological parameter.

Results: There were 10% more drops in temperature observed in T4 (95%CI: 3-17%), and more increases in temperature observed during T1 (4%; 95%CI -2-9%). An excess number of wind speed increases (9%;95%CI 2-16%) and relative humidity increases (6%; 95%CI 0.1-14%) occurred during T4. Additionally, female patients in this cohort presented less often than male patients following drops in average temperature.

Conclusions: Using a new method for integrating meteorological data into a clinical trial dataset, we identified associations between changes in weather conditions and the likelihood of an ACS event.

Trial registration: ClinicalTrials.gov NCT00089895.

Keywords: Acute coronary syndromes; Climate; Temperature.