Temporal and meteorological determinants of emergency department visit volume: a 24-month time-series analysis from a tertiary hospital in Istanbul
This 24-month time-series analysis of a tertiary emergency department in Istanbul reveals that daily visit volumes are significantly driven by a non-linear inverted-U relationship with temperature, precipitation levels, day-of-week patterns, religious calendar events (Ramadan and Eid), influenza surveillance data, and major natural disasters, providing a quantitative basis for dynamic capacity planning beyond fixed seasonal models.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Hospitals are living organisms that breathe in rhythm with the world outside their walls. Just as a city's traffic flows differently on a rainy Tuesday than on a sunny Saturday, the number of people walking through emergency room doors changes constantly. This volume is not random; it is driven by a complex mix of the weather, the calendar, and the deep cultural rhythms of the society it serves. When a heatwave hits, when a religious holiday begins, or when a storm rolls in, the people who need urgent care change, and so does the number of people arriving. Understanding these patterns is not just an academic exercise; it is a matter of life and death for the hospitals themselves. If a hospital knows exactly when the crowd will swell, it can staff its doctors and nurses accordingly, ensuring that the right care is available the moment it is needed. Without this knowledge, emergency departments face a constant struggle against overcrowding, which slows down treatment and increases the risk of errors.
In a large, bustling hospital in Istanbul, researchers set out to map these invisible rhythms over a period of two years. They looked at nearly 1.2 million visits to the emergency department, tracking every single day from January 2024 through the end of 2025. Their goal was to build a clear picture of what actually drives people to seek emergency care. They did not just look at the weather; they also examined the Turkish calendar, which includes secular holidays, the Islamic month of Ramadan, and the festivals that follow it. They even looked at how a major natural disaster, an earthquake that struck the region in April 2025, altered the flow of patients. By combining daily weather data with hospital records, the team could separate the noise of random events from the steady, predictable patterns that govern the emergency room.
The most striking discovery was how temperature shapes the daily crowd. The relationship between heat and hospital visits is not a straight line where more heat always means more patients. Instead, the researchers found a curve that rises and then falls. As the temperature climbs, the number of visits increases, reaching a peak when the daily high hits about 31 degrees Celsius. Beyond that point, as the heat becomes extreme, the number of people arriving actually begins to drop. This suggests that while moderate warmth brings out more people, perhaps due to increased activity or minor health issues, extreme heat keeps people indoors, sheltering from the sun and delaying their trips to the hospital unless they are critically ill. This inverted shape was consistent and robust, appearing clearly in the data regardless of the time of year.
Rain, too, plays a significant role, but in the opposite direction. The study showed that when it rains, fewer people come to the emergency room. Specifically, for every millimeter of rain that falls over a three-day period, the daily number of visits drops by a measurable amount. It seems that wet weather acts as a natural barrier, keeping people at home and discouraging them from making non-urgent trips to the hospital. This effect was steady and predictable, adding another layer to the weather's influence on hospital capacity.
Perhaps the most culturally specific findings came from the religious calendar. The month of Ramadan, a time of fasting from dawn to dusk, brought a dramatic shift in the daily rhythm of the emergency room. During this month, the total number of visits dropped significantly compared to other times of the year. However, the timing of those visits changed completely. Instead of arriving during the day, patients shifted their visits to the evening and night. The hours just after sunset, when the fast is broken, and the early morning hours before dawn saw a surge in activity. This indicates that the physical and social changes of fasting alter when people feel the need to seek help, pushing the demand for care into the night.
The period immediately following the major religious festivals, known as Eid, revealed another powerful pattern. While the festival days themselves saw a slight dip in visitors, the week that followed was a time of intense activity. For seven days after the holiday, the hospital saw a massive increase in patients, with hundreds more people arriving each day compared to a normal week. This "return week" effect suggests that people who delayed their medical care during the holiday, or who traveled back to the city from other regions, flooded the emergency rooms once normal life resumed. This finding is crucial for hospital planners, as it shows that the pressure on the system peaks not during the holiday, but in the week after it ends.
The researchers also looked at what happens when the ground shakes. When a magnitude 6.2 earthquake struck the Marmara region in April 2025, the overall number of people coming to the emergency room dropped sharply for three days. This counterintuitive result suggests that in the immediate aftermath of a disaster, people stay home, perhaps due to fear, damage to roads, or a belief that the hospital is overwhelmed. Yet, the nature of the patients who did arrive changed. While the total crowd shrank, the proportion of the most critical, life-threatening cases increased significantly. This means that while the hospital was less crowded overall, the patients who did make it through the doors were in far more urgent need of immediate, high-level care.
The study also explored the link between respiratory viruses and hospital visits. By tracking national data on flu-like illnesses, the researchers found that as the number of people with respiratory symptoms in the community rose, so did the number of visits to the emergency room. This connection was strongest for patients with less severe conditions, who made up the bulk of the increase. This suggests that when a virus is spreading, the emergency room becomes a place for managing a wide range of minor to moderate ailments, adding to the daily load in a way that is distinct from the weather or the calendar.
Other factors, such as football matches between rival teams or strikes by doctors, did not show a measurable impact on the total number of daily visits. This indicates that while these events are significant in the news, they do not disrupt the fundamental flow of emergency care in the way that weather and holidays do. The study concluded that the daily volume of emergency visits is a predictable outcome of the environment and the culture. By understanding the inverted curve of temperature, the dampening effect of rain, the shifting rhythms of religious observance, and the surge that follows holidays, hospital administrators can move beyond guessing. They can prepare for the specific, real-world forces that bring people to their doors, ensuring that the hospital is ready for the crowd that is coming, whether it is driven by the sun, the rain, or the calendar.
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