As temperature soars, overall deaths also go up: Study

As the city continues to swelter under the summer heat, it is perhaps time to take a look at number of deaths due to unforgiving heat this year. Even if the statistics of mortality don't point out to heat, a study conducted in Surat way back in 2016 says otherwise. It shows how all-cause mortality (death due to any cause) has seen a rise when temperature soars. The expert also pointed out to the need to identify the cause of death that relate to heat.

The study published in the Indian Journal of Community Medicine in the year 2017 assesses the effect of daily maximum temperature relative humidity and heat index on spatial variability of all-cause mortality for summer months (March to May) from 2014 to 2015 for the urban population of Surat.

It analysed the all-cause mortality data of 9,237 deaths with temperature and humidity for 184 summer days of 2014 and 2015.

The study found that the mortality saw a rise of 20 per cent per day at temperatures that were greater than 40 degree Celsius.

It also found variations in the deaths being reported from different zones with 61 per cent all-cause mortality rise for Southeast and 30 per cent for east zones of Surat when temperatures touched above 40 degree Celsius.

This also showed that certain areas and zones of the city were at particularly high risk due to the heat compared to others.

The study was authored by Dr Suresh Kumar Rathi, Dr. Vikas Desai, Priyanka Jariwala, Dr. Hemant Desai, Dr. Asshish Naik and Arpit Joseph

Dr Suresh Kumar Rathi, lead author of the paper, and Associate Professor with the Indian Institute of Public Health (IIPH) Hyderabad said that one of the key takeaways from the study was how heat can have different impacts in different places of the same city. He further added that the spatial variability in the study also reinforces what many public health practitioners believe that particular areas of a city need more focus than others.

"Moreover, one of the things that needs to be done is to create awareness and sensitize about heat stroke and heat-related deaths among doctors and para-medical staff at various levels. By this I don't mean just training them in identifying heat stroke symptoms, which they are already trained to do," said Dr Rathi, who was associated with the Urban Health and Climate Resilience Centre in Surat when the study was carried out.

He said as the study shows, the number of deaths go up as temperature rise but not all deaths are attributed to heat are reported. "Often when a patient has other conditions like diabetes, hypertension, etc., the death may not be reported as being caused due to heat. But we need to know what triggered it and heat may be the cause," said Dr Rathi. He said it is very important and doctors are also trained to mention heat / heat stroke is the cause of death in death certificate. "That is how we will be able to collect data about deaths whose underlying cause may be rise in temperature and it will help us in framing better policies to battle it," said Dr. Rathi.

The study attributed higher number of deaths in particular zones of Surat to a deadly combination of population density, industries, and slums with migrant population making them vulnerable to all-cause mortality due to high temperature.

Dr Maharshi Desai, a critical care specialist with Apollo Hospital in the city said the findings should not come as a surprise. "Heat has adverse impact on two kinds of people. Those who work in the sun and those who have borderline medical conditions or other severe ailments. In the latter, heat can have an impact even if they are necessarily outside in the sun. It may not be the only reason but it can definitely contribute to the mortality," he said

Healthy people when exposed to heat can succumb to heat stroke in the event of lack of proper medical care.

"Those who are sick need not be exposed to the sun to worsen their condition. Ambient temperature above 40 or 45 degree Celsius contributes to the pre-existing problem and leads to mortality," said Dr Desai. He said that in such cases it is also not possible to mention heat as a cause of death or one of the contributing factors because it is often not obvious.

DEADLY HEAT

Study assessed the effect of heat on all-cause mortality Often when a patient has conditions like diabetes, hypertension, etc., death may not be reported as being caused due to heat. But we need to find it out if heat was the cause — Dr. Suresh Kumar Rathi, Urban Health & Climate Resilience Centre

THE FINDINGS

1. Analysis of weather stations showed that East and Southeast zones of Surat were 3°C-4°C warmer than other zones on a given day. 

2. When temperatures reached above 40°C the average deaths per day increased from 48.01 to 57.26 (9.25) or 20% rise in average per day all-cause mortality. 

3. Minimum deaths per day at daily maximum temperature of <35°C was 3.6. This increased to 5.8 during daily maximum temperature of ≥ 40°C for Southeast zone.  

4. This means that 2.2 (61%) deaths per day increased at the temperature of ≥ 40°C for Southeast zone.