Table 2

Risk of bias: reporting of exposures measured, adjustment for confounders and proportion of variables associated with asthma or wheeze

DesignStudyISAAC questionnaireExposures measuredExposures reportedCriteria for presentationAdjustment for confoundersHygiene exposures with association (P<0.005)Non-hygiene exposures with association (P<0.05)Total exposures with association (P<0.005)
CohortBrandão et al45 46Yes43 (6–7 years)?
34 (13–14 years)?
Not described for univariate analysis. Variables reported varied between the different agesYes3/73/156/22
SCAALA Brazil9 15 16 20 21Yes5550‘Meaningfully associated’ in univariate or multivariate analysis (with Schistosoma mansoni and hookworm excluded from analysis)Yes4/281/225/50
Pelotas cohort23 24 26Modified20?20Not described for multivariate. No hygiene exposure in multivariate*Yes*1/57/158/20
Cuban study60–62Modified2524One more variable only used as confounder in multivariateYes2/156/108/25
ECUAVIDA22 25Modified47?25Not described, except confounders chosen for significant associations with the 5-year AW phenotype and on previously reported associations with asthma or with microbiome shiftsYes3/124/137/25
Zepeda et al27No1514Not describedNo1/120/31/15
Cross-sectionalSCAALA Ecuador10 30 31Yes4727P<0.2 in univariate analysis or included in multivariate analysis. Parasites with low prevalence not representedYes5/152/327/47
Uruguaiana study13 14Yes41?11–12Risk factors known to be associated with wheeze/asthma and those significantly associated in the bivariate analysis. Intestinal parasitesYes†1/116/307/41?
Azalim et al32Modified?12Not describedYes0/24/114/13
Barraza et al33Yes?16Not describedYes2/38/1310/16
Barreto and Sole28Yes3315P<0.2 in univariate analysis and P<0.05 in bivariate analysisNo3/?12/?15/33
Bragagnoli and Silva63Yes1815Only presented results for the Ascaris lumbricoides coinfections with other parasites (not those other parasites alone)No3/142/45/18
Casagrande et al29Yes33?31Not described (P<0.2 in univariate analysis to include in bivariate)Yes0/112/202/31
Cooper et al64Yes43Not specified (low proportion of Ancylostoma duodenale?)Yes0/30/3
Del-Rio-Navarro et al44Yes43 (6–7 years)
34 (13–14 years)
Statistically significant results (for univariate and multivariate)Unclear1/1
Endara et al65Yes1 (+6 parasites)1No association with intestinal parasitesYes0/1 (7)00/1 (7)
Freitas et al66Yes6510P<0.2 in univariate was included in multivariate. Final model variables P<0.05Yes1/102/553/65
Garcia et al67Yes3512P<0.25 in bivariate analysisYes1/35/326/35
Gomes de Luna et al68Modified3434Yes0/14/334/34
Guimarães et al69No1414No0/22/122/14
Hagel et al7022No0/20/2
Han et al71 72Modified37?21/26Not specifiedYes§2/1311/2413/37
Kuschnir and Alves da Cunha73Yes3410Not statedYes2/33/315/34
Lima et al74Modified99Yes0/13/83/9
Maia et al75No83P<0.05 in final multivariate modelYes1/12/73/8
Palvo et al76Modified149P<0.2 in univariate analysis and P<0.05 in multivariate analysisYes1/45/106/14
Prietsch et al77No28?17P<0.2 in univariate analysis (to be included in multivariate)Yes1/66/227/28
Quiroz-Arcentales et al42No15?5Not statedNo4?/56?/1010?/15
Ribeiro et al78No177Not statedNo0/51/121/17
Rojas Molina et al34Modified?3–4Only significant variablesNo1/?2–3/?3–4/?
Silva et al79No11Yes0/1-0/1
Solis-Soto et al35Yes?9Not specifiedYes1/52/43/9
Soto-Quiros et al80No1010No1/14/95/10
Souza et al8110No result for asthma alone (only for respiratory allergy)No0/10/1
Tintori et al82No14?14P<0.5 in univariate was included in multivariate. Final model variables P<0.05Yes1/211/1212/14
Toledo et al83Modified124Not statedNo0/40/80/12
Case–controlBoneberger et al43Modified1311Matched by sex and age (not represented)Yes3/61/74/13
Cadore et al84No14?14Yes1/45/106/14
Coelho et al47Yes67?35Not stated. P<0.2 in bivariate included in multivariateYes2/114/246/35
Jucá et al85Yes67?26Not stated. P<0.2 in bivariate included in multivariateYes1/107/588/68
López et al8611No0/10/1
Mendoza et al8766No1/61/6
Moraes et al88No2222Unclear¶1/31/192/22
Oliveira-Santos et al89Yes67?26Not stated. P<0.25 in bivariate included in multivariateYes2/61/203/26
Rizzo et al90No30‘No significant difference’ in text, but no numbers representedNo0/20/10/3
  • ?: unclear number or not included.

  • *Muiño et al26: no description of variables measured and represented. No adjustment.

  • †Only for Pereira et al14 not da Silva et al.13

  • ‡Same questionnaire as SCAALA Ecuador.

  • §Only rural residence and antibiotic use and bronchiolitis in the first year of life were adjusted for in multivariable analysis, as was the objective of the study.

  • ¶Not published.

  • Exposures associated to wheeze or asthma: shown over total exposures measured or represented (when number of exposures measured was not clear). When results presented were divided in subgroups, highest number of associated variables from any of the subgroups was selected for the table.

  • AW, atopic wheeze; ISAAC, International Study on Asthma and Allergies in Children; SCAALA, Social Changes, Asthma and Allergy in Latin America.