Which population level environmental factors are associated with asthma, rhinoconjunctivitis and eczema? Review of the ecological analyses of ISAAC Phase One

Table 3 Symptoms of eczema in the past 12 months - summary of ecological analyses*.

Ecological Issue	Specific Factor	13-14 Year Age Group		6-7 Year Age Group
		Direction of effect	P Value	Direction of effect	P Value
Economic development	GNP	+	0.05	+	0.02
Diet	Calories from cereals and rice %	-	0.246	-	0.767
	Protein from cereals and nuts %	-	0.028	-	0.07
	Starch g/d	-	0.560	-	0.058
	Vegetables g/d	-	0.001	-	0.157
	Vegetable Vitamin A μ/d	-	0.001	-	0.153
	Trans fatty acids	+	< 0.0001
Immunisation	Local immunisation rates for DTP#	-	0.048	-	> 0.05
	Local immunisation rates for measles	-	0.036	-	> 0.05
TB exposure	TB notification rates, WHO	+	0.544
Outdoor climate	Latitude	0	> 0.05	+	> 0.05
	Altitude	+	> 0.05	+	> 0.05
	Mean annual temperature	-	> 0.05	-	> 0.05
	Annual variation in mean temperature	+	< 0.05	+	> 0.05
	Lowest monthly mean temperature	-	> 0.05	-	< 0.05
	Annual variation in mean relative humidity	-	> 0.05	-	> 0.05
	Lowest monthly mean relative humidity	-	> 0.05	-	> 0.05
Indoor climate	Mean annual relative humidity	-	> 0.05	-	< 0.05
	Lowest monthly mean relative humidity	0	> 0.05	-	> 0.05
Tobacco smoking	Tobacco consumption, ≥ 15 yrs	+	0.35	+	0.87
	Tobacco smoking, women	+	0.42	+	0.17
	Tobacco smoking, men	-	0.007	-	0.67
Pollen	Total grass pollen count	-	0.15
	Days with high pollen counts	-	0.32
Antibiotic usage	Antibiotic sales per capita	-	0.46
Air pollution	PM₁₀	-	0.07	-	0.10
Paracetamol	Per capita paracetamol sales	+	< 0.0005	+	0.001

*standardized for GNP. Where p values are recorded as > 0.05 the non significant p values were not provided in the source publication. #DTP = Diphtheria and tetanus toxoids and pertussis.
Blank space = data not collected. + = positive association. - = inverse association. 0 = no association.

ISSN: 1465-993X