***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Little is known about the prevalence of atopic eczema outside Northern Europe . OBJECTIVES We sought to describe the magnitude and variation in the prevalence of atopic eczema symptoms throughout the world . METHODS A cross-sectional question naire survey was conducted on r and om sample s of schoolchildren aged 6 to 7 years and 13 to 14 years from centers in 56 countries throughout the world . Those children with a positive response to being question ed about the presence of an itchy relapsing skin rash in the last 12 months that had affected their skin creases were considered to have atopic eczema . Children whose atopic eczema symptoms result ed in sleep disturbance for 1 or more nights per week were considered to have severe atopic eczema . RESULTS Complete data was available for 256,410 children aged 6 to 7 years in 90 centers and 458,623 children aged 13 to 14 years in 153 centers . The prevalence range for symptoms of atopic eczema was from less than 2 % in Iran to over 16 % in Japan and Sweden in the 6 to 7 year age range and less than 1 % in Albania to over 17 % in Nigeria for the 13 to 14 year age range . Higher prevalences of atopic eczema symptoms were reported in Australasia and Northern Europe , and lower prevalences were reported in Eastern and Central Europe and Asia . Similar patterns were seen for symptoms of severe atopic eczema . CONCLUSIONS Atopic eczema is a common health problem for children and adolescents throughout the world . Symptoms of atopic eczema exhibit wide variations in prevalence both within and between countries inhabited by similar ethnic groups , suggesting that environmental factors may be critical in determining disease expression . Studies that include objective skin examinations are required to confirm these findings BACKGROUND The aim of the International Study of Asthma and Allergies in Childhood ( ISAAC ) was to evaluate the prevalence of symptoms of eczema among children living in different parts of Latin America . Data were from centers that participated in ISAAC Phase 3 . METHODS This was a cross-sectional question naire survey of 93,851 schoolchildren ( 6 to 7 years old ) from 35 centers in 14 Latin American countries and 165,917 adolescents ( 13 to 14 years old ) from 56 centers in 17 Latin American countries . RESULTS The mean prevalence of current flexural eczema in schoolchildren was 11.3 % , ranging from 3.2 % in Ciudad Victoria ( Mexico ) to 25.0 % in Barranquilla ( Colombia ) . For adolescents , the prevalence varied from 3.4 % in Santo And ré ( Brazil ) to 30.2 % in Barranquilla ( mean prevalence , 10.6 % ) . The mean prevalence of current symptoms of severe eczema among schoolchildren was 1.5 % , ranging from 0.3 % in Ciudad Victoria , Toluca , and Cuernavaca ( Mexico ) to 4.9 % in La Habana ( Cuba ) . For adolescents , the mean prevalence was 1.4 % , ranging from 0.1 % in Mexicali Valley ( Mexico ) to 4.2 % in Santa Cruz ( Bolivia ) . These prevalence values are among the highest observed during ISAAC Phase 3 . In general , the prevalence of current symptoms of eczema was higher among the Spanish-speaking centers for both schoolchildren and adolescents . CONCLUSION Environmental risk factors must be evaluated in order to identify potential causes for the differences observed , even in centers from the same country BACKGROUND The association between allergic sensitization and eczema has been debated for years . OBJECTIVE We sought to determine and compare the strength of the association between allergen skin sensitization and eczema in both developing and industrialized countries . METHODS Twenty-eight thous and five hundred ninety-one r and omly selected 8- to 12-year-old schoolchildren in 20 countries were physically examined for flexural eczema and received skin prick testing to Dermatophagoides pteronyssinus , Dermatophagoides farinae , cat hair , Alternaria tenuis , mixed tree and grass pollen , and allergens of local relevance . RESULTS The age- and sex-adjusted odds ratios ( ORs ) for a positive association between flexural eczema and atopy ranged between 0.74 ( 95 % CI , 0.31 - 1.81 ) and 4.53 ( 95 % CI , 1.72 - 11.93 ) , with a significantly stronger association in affluent compared with nonaffluent countries ( combined age- and sex-adjusted OR(affluent ) = 2.69 [ 95 % CI , 2.31 - 3.13 ] and OR(nonaffluent ) = 1.17 [ 95 % CI , 0.81 - 1.70 ] ) . The combined population attributable fraction for atopy in flexural eczema was 27.9 % for affluent and 1.2 % for nonaffluent-country centers . Correlating gross national per-capita income with either ORs or population attributable fractions for atopy in flexural eczema confirmed a highly significant positive association ( P = .006 and P < .001 , respectively ) . CONCLUSIONS The association between atopy and flexural eczema is weak and more variable than previously suggested , and the strength of this association is positively linked to gross national income Background Question naires are widely used in epidemiological studies to measure eczema symptom prevalence , but there are concerns regarding their accuracy if used as a diagnostic tool 
    Output:
    
Conclusions and Relevance Skin and subcutaneous diseases were the 18th leading cause of global DALYs in Global Burden of Disease 2013 .
Excluding mortality , skin diseases were the fourth leading cause of disability worldwide