Epidemiological features of allergic rhinitis in four major cities in Western China.

Allergic rhinitis (AR), with an increasing uptrend of the prevalence in many developed and developing countries, is a global health problem that affects people of all ages and ethnic groups. However, data on the prevalence of self-reported AR in western China are rare. This study investigated the epidemiological features of self-reported AR in western China. In the cross-sectional, population-based study, a validated questionnaire survey on self-reported AR was carried out in 4 major cities in western China by multistage, stratified and cluster sampling, from January to December 2008. The total prevalence rate was 34.3%, with 32.3% (Chongqing), 34.3% (Chengdu), 37.9% (Urumqi), 30.3% (Nanning), respectively. The prevalence presented to increase with age before 30 years old while decrease with age after 30 years old, and the highest prevalence was in 19-30 years group in Chongqing, Chengdu and Nanning which significantly showed "persistent and moderate-severe" type (P<0.0001); In Urumqi, there wasn't a significant increasing or decreasing trend of prevalence rate with age but with an "intermittent and mild"predominance (P<0.0001). There were no distinct sexual differences in prevalence rates in the 4 cities. The morbidity was positively related to monthly average temperature and sunshine (r=0.76645, P=0.0036; r=0.67303, P=0.0165), but negatively associated with relative humidity (r=-0.64391, P=0.0238) in Urumqi. Interestingly, the monthly morbidity was negatively associate with average temperature, sunshine and precipitation in Nanning (r=-0.81997, P=0.0011; r=-0.60787, P=0.0360; r=-0.59443, P=0.0415). Self-reported AR is becoming common in western China with a rapid development in recent years, affecting about three persons out of ten. The climatic factors may have an indirect impact on the prevalence rate through the effects on the local allergens.