Syed Haider Hasan Alam, Zohaib Yousaf, Zeeshan Butt, Saira Afzal.
Correlation between the Number of Outdoor Visits and Climate Variables for Asthmatics in a Developing Country: A Retrospective Study.
Pak J Med Health Sci Jan ;6(2):483-7.

Background: Seasonal variations in the frequency of asthma visits and admissions are recognized widely, but there is a dearth of studies that associate the seasonal variation with the asthma visits in the pediatric age group in Pakistan. Methods: The study was conducted on electronically compiled data of 19,712 patients from a period of 6 years (2004-2009) who came to the asthma clinic. The percentages of asthma outdoor visits per month were calculated and compared over the 6 year period. Pearson correlation was used to analyze the relation between the number of outdoor visits, and the Mean Monthly Temperature and Mean Monthly Humidity. Results: Out of the total 19,712 visits, 55.9% were male patients and 44.1% were female patients. A 13-fold rise in the number of asthma visits was seen in 2009 as compared to 2004. The highest number of asthma visits was in September through December (winters). The temperature in these months was low and the humidity high. The number of visits was at their lowest in May (summer) when the temperature was high and the humidity low. This pattern was not affected by age group or gender. A negative correlation was seen between the number of outdoor visits of asthma patients and the Mean Monthly Temperature (-0.03), and a positive correlation (0.15) was seen between the number of outdoor visits of asthma patients and the Mean Monthly Humidity, but overall it was not significant (p=0.83 and p=0.21 respectively). Conclusions: The number of asthmatics is on the rise in Pakistan. A negative correlation was seen between the number of outdoor visits and the Mean Monthly Temperature, and a positive correlation was seen between the number of outdoor visits of asthma patients and the Mean Monthly Humidity.

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