Aim: Asthma is a common chronic condition in both children and adults worldwide and it has a high socio-economic cost. Little is known about asthma in Tibet and especially about asthma in rural and high altitude parts of the country. There is therefore a need to increase the knowledge of asthma and asthma related diseases and symptoms in this part of the world. The aim of my study was therefore to assess prevalence of asthma and asthma related symptoms and diseases among school children in the rural high altitude parts of Tibet. Furthermore, to study environmental exposures and family related conditions and if these conditions were related to disease and symptom occurrence in this population.
Methods: A cross-sectional study was carried out among 2026 children 12 to 14 years of age in two counties Tingri and Sagya in Shigatse District, Tibet. These counties were chosen because they were considered representative for the rural population of Shigatse District and were accessible for our data collection team. The questionnaire consisted of the core questions regarding wheezing, asthma, eczema and rhinitis from the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. The core included questions about experience of various symptoms visualized by a video. Data on environmental exposures and living conditions was collected and the participants’ height and weight were measured.
Results: Knowledge about asthma was reported by 4.2% of the children (1.4% in Tingri, 6.9% in Sagya, p<0.01). The prevalence of asthma, hay fever, rhinitis and eczema were 2.4%, 5.8%, 8.7% and 9.1%, respectively. 6.8% of children reported ever wheezing or whistling in the chest, while wheezing during the past 12 months was reported by 2.6% of the children. The symptom was reported less often among girls than boys (p=0.01). The over all prevalence of the symptoms visualized by video was 2.8% for wheeze at rest and 1.1% for wheeze at rest during the last 12 months. 3.4 % of the mothers and 35.3% of the fathers were current smokers and similar percentages were reported for former smoking habits. Most of the families used wood and yak and/or sheep dung for fuel when cooking and heating. In 65.3% of the homes they kept dogs inside. This was more common in Tingri than Sagya (p<0.01). There was a statistically significant association between mothers smoking and severe asthma (OR, 5.0; 95%CI, 1.7 to 14.7). There was also a clear relation between reports of indoor dampness and/or mold problems and the prevalence of asthma symptoms. This included symptoms like wheeze at rest (adjusted OR, 2.2; 95% CI, 1.3 to 3.8), night waking with wheeze (adjusted OR, 2.0; 95% CI, 1.1 to 3.9), night waking with cough (adjusted OR, 2.0; 95% CI, 1.3 to 3.3) and severe wheeze (adjusted OR, 2.6; 95% CI, 1.3 to 5.5). Children from large families had more asthma symptoms than children from small families.
Conclusions: Compared with most western countries Tibetan children living in a rural district reported fewer symptoms of asthma and asthma related diseases. The symptoms and disease occurrence are more similar to findings from countries such as India, China and Russia. The present findings are therefore in accordance with the general view that the western lifestyle in some way increases the risk of developing these diseases. The cause of this is not understood, and the study could not add much to the understanding of that research question. The data did not support the hypothesis that large families or having many siblings have a protective effect on the development of these diseases. However, in accordance with many other studies, I found that indoor dampness/molds increase the risk of having asthma symptoms. The level of exposure to indoor pollutants from the burning of biomasses was high for most of the children. Due to the small variation in this exposure it is unlikely that I should have been able to show that methods of heating and cooking were related to the disease and symptom outcomes. However, it is interesting that a population with heavily exposed children still has low symptom prevalence. I would recommend that several issues from the present study should be investigated in more detail.