Asthma, COPD most common respiratory diseases among Indians, less prevalent during summer: Study
Asthma and chronic obstructive pulmonary disorder (COPD) are the most common respiratory illnesses among Indians, according to a multi-centre survey conducted at outpatient clinics across the country. Carried out on four different days of the year representing seasonal transitions – winter, summer, monsoon and autumn – the survey also found that respiratory illnesses showed significant seasonal trends and were less prevalent during summers.
This seasonal waves of respiratory disorders (SWORD) study was conceived and coordinated at Asthma Bhavan, an independent research institute in Jaipur, and subsequently conducted in 2017-18. It was published in PLOS One on August 18 this year.
Conducted across 302 sites covering 25,177 adults, the study showed that the common diagnoses were asthma (29.8 per cent), COPD (15.6 per cent), respiratory tract infections (11.3 per cent) and tuberculosis (8.7 per cent).
“All these conditions showed significant seasonal trends (asthma 31.4 per cent autumn vs. 26.5 per cent summer, COPD 21.1 per cent winter vs. 8.1 per cent summer, RTIs 13.3 per cent winter vs. 4.3 per cent summer, and tuberculosis 12.5 per cent autumn vs. 4.1 per cent summer,” Bharat Bhushan Sharma from the department of medicine, division of allergy and pulmonary medicine, SMS Medical College, Jaipur, said in the report.
Asthma was significantly associated with exposure to molds, pet animals, recent travel and rain-wetting, said researchers. The study said that a significant association was found with trigger factors for each respiratory disease — exposure to molds, household animals, recent travel and rain-wetting for asthma; biomass fuel and smoking for COPD; rain-wetting and recent travel for respiratory tract infections.
According to the study, the prevalence of COPD increased with age for both men and women. After the age of 40, COPD was found to be almost twice as common among men than among women, said Dr Sundeep Salvi, one of the researchers and director of Pune-based Pulmocare Research and Education Foundation.
Asthma, COPD, tuberculosis and respiratory tract infections showed a dip in numbers mainly during summer, according to the study. The low prevalence of symptomatic respiratory patients during summer in the SWORD study is intriguing and could be partly explained by environmental factors, including a rise in ambient temperature and prolonged, overhead and intense sunlight throughout the days, less vegetation and molds.
Seasonal variation mainly depends on temperature, precipitation and the productivity of the biosphere. The latter part of summer and the beginning of monsoons is marked by rains, fluctuations in temperature and changes in flora and fauna. These may be responsible for the rise in respiratory illnesses during this period, according to the study. The high prevalence of respiratory disease-related outpatient visits is maintained subsequently in winters probably due to a rise in pollution or mixed effect of viral-related illnesses, it said.
According to the study, the proportionate symptomatic burden due to tuberculosis was about 8.7 per cent and it showed that the prevalence of the disease is still high despite the implementation of national-level tuberculosis programmes. The goal of eradicating tuberculosis in India by 2025 remains a formidable challenge, the researchers said.
Of the patients surveyed, 3,803 (15.1 per cent) belonged to below-poverty-line (BPL) families. As many as 2,539 (10.1 per cent) patients were asymptomatic and revisits were 14,692 (58.4 per cent). Among respiratory symptoms, breathlessness (15,287, 60.7 per cent) was the most common complaint.
