The Association between Cold Spells and Pediatric Outpatient Visits for Asthma in Shanghai, China

Abstract

BackgroundAsthma is a serious global health problem. However, few studies have investigated the relationship between cold spells and pediatric outpatient visits for asthma.ObjectiveTo examine the association between cold spells and pediatric outpatient visits for asthma in Shanghai, China.MethodsWe collected daily data on pediatric outpatient visits for asthma, mean temperature, relative humidity, and ozone from Shanghai between 1 January 2007 and 31 December 2009. We defined cold spells as four or more consecutive days with temperature below the 5th percentile of temperature during 2007–2009. We used a Poisson regression model to examine the impact of temperature on pediatric outpatient visits for asthma in cold seasons during 2007 and 2009. We examined the effect of cold spells on asthma compared with non-cold spell days.ResultsThere was a significant relationship between cold temperatures and pediatric outpatient visits for asthma. The cold effects on children's asthma were observed at different lags. The lower the temperatures, the higher the risk for asthma attacks among children.ConclusionCold temperatures, particularly cold spells, significantly increase the risk of pediatric outpatient visits for asthma. The findings suggest that asthma children need to be better protected from cold effects in winter.

The short-term association between asthma hospitalisations, ambient temperature, other meteorological factors and air pollutants in Hong Kong: a time-series study

“…The nature of associations reported from past studies of asthma morbidity and temperatures have not been consistent, likely due to differences in climate, study design and statistical methodology. Some studies have found positive associations between temperatures and asthma admissions,23 24 some have reported negative associations,2 5 7 8 16 19 25 26 while a few have reported significant associations with high and low temperatures 6 27. The seasonal differences in associations of RH with asthma hospitalisations observed in this study, negative association in the cold season and positive in the hot season, have not been commonly reported in previous studies.…”

“…Maximum lags of 20–30 days have been commonly used in modelling temperature due to the relatively longer observed lagged effect of cold temperature,2 7 18 19 while lagged effect of air pollutants are usually shorter 20. Maximum lags for DLNMs were chosen by comparing relative risk (RR)–lag associations generated from initial DLNMs using different maximum lags (10–30 days).…”

“…However, the nature of these associations varied across studies in different geographic locations, likely due to differences in climate, socioeconomic development, and genetic characteristics. A study from Australia6 reported a positive association between childhood asthma morbidity and temperature, while a study from Shanghai2 reported higher numbers of admissions during periods of low temperature. In Hong Kong, large diurnal temperature ranges were found to be associated with more emergency hospital admissions for asthma 11.…”

Prevalência de diagnóstico médico de asma em adultos brasileiros: Pesquisa Nacional de Saúde, 2013

“…With regard to the macroregions of the country, in both the PNAD and the current research, the southern area showed a higher prevalence of asthma medical diagnosis, regardless of the age 7,20 . Access to health services might be one of the factors responsible for more diagnosis in the South; another aspect as to the southern area is its climate, because several studies in literature mention the cold temperature as a "trigger" for asthma crisis 25,26 . Nevertheless, one of the difficulties in understanding the higher asthma prevalence in some regions of the country is because Brazil does not have a single genetic standard.…”

Asthma hospitalisations and air pollution

“…However, studies have varied in the relationships found, with some suggesting high and others low temperature associations with asthma morbidity 1–3. Several air pollutants, such as particulate matter, NO 2 and O 3 , have been inconsistently associated with asthma and inevitably temperature confounds associations between asthma and pollutants 2 4. In addition, ambient temperature, particularly in temperate climates, may affect dry powder inhaler drug stability, and this may inadvertently confound worsening asthma control in areas of high humidity and high temperature, such as Hong Kong 5 6…”