- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
Objective: There are no community based, longitudinal, intra individual epidemiological studies on effect of weather and season on blood pressure. We evaluated the effect of season and temperature on prevalence and epidemiology of BP in tropical climate. Methods and results: It was a longitudinal cross sectional survey of rural and urban subjects in their native surroundings. BP was measured in four different seasons in same subjects. A total of 978 subjects (452 rural and 521 urban) were included in the current analysis. Demographic characteristics such as age, gender, education, occupational based physical activity and body mass index were recorded. Mean BP, both systolic and diastolic were significantly higher in winter season as compared to summer season. Mean difference between winter and summer was 9.01 (95% CI: 7.74–10.28, p < 0.001) in systolic BP and 5.61 (95% CI: 4.75–6.47, p < 0.001) in diastolic BP. This increase in BP was more marked in rural areas and elderly subjects.Prevalence of hypertension was significantly higher during winter (23.72%) than in summer (10.12%). Conclusion: BP increases significantly during winter season as compared to summer season. Increase is more marked in rural areas and elderly subjects. Seasonal variation in BP should be taken into account while looking at prevalence of hypertension in epidemiological studies.
The present study was conducted in a community setting, both rural and urban areas of North India and BP was recorded in out-ofclinic settings in native surroundings (either home or workplace). The study shows that there was significant seasonal variation in BP. Highest BP (Mean SBP/DBP) were observed during winter (131.28/ 83.24 mm Hg) and lowest during summers (122.27/77.69 mm Hg). There are very few studies available from developing countries.3,5,6 A study from China demonstrated a significant increase in clinic blood pressure (SBP/DBP) by 10/4 mm Hg between summer and winter which is similar to our study.6 Another clinic based study from rural China also showed that there was significant difference in adjusted SBP/DBP (19.2/7.7 mm Hg) between winter and summer.5 However, both these studies were clinic based. Our study is the largest study from a developing country in out-ofclinic settings. An increase in prevalence of hypertension during winter as compared to other seasons was noticed in the current study. Prevalence became more than doubled during winter (23.72%) as compared to summer season (10.12%). Similar finding was reported recently in a study from rural China where hypertension detection during winter was twice high (50.6%) as compared to summer (19.4%).5 Few other studies have also reported the same.15–18 However, most of these studies were hospital based.A recent epidemiological survey reported that an increase of 1C in air temperature reduced hypertension prevalence at two survey visits with an odds ratio of 0.98 (95% confidence interval: 0.96–0.99).