Table 3.
Systematic reviews of hygiene hypothesis related interventions and the risk of food allergy or food sensitization.
| First Author (Year) AMSTAR Quality Meta-analysis MA (+ or −) |
Study Designs included in review & search dates | Population/s studied and numbers | Intervention/s and comparisons | Outcome measures | Main results | Authors’ Conclusions |
|---|---|---|---|---|---|---|
|
Arnoldussen (2011) [86] Quality: Medium MA− |
1 Randomized prospective single blind study 1 Retrospective Cohort study No search dates stated |
High allergy risk RCT- BCG = 62 Placebo = 59 Cohort- Atopic hereditary children 216 cases, 358 controls |
BCG vaccination |
Food allergy: Symptoms of allergy (skin reactions, wheezing, vomiting, or diarrhoea) on more than one occasion after ingestion or contact with a particular type of food or allergen (1 study) Symptoms of feeding induced vomiting diarrhoea or abdominal pain (1 study) |
Results not pooled because outcomes were judged to be too heterogeneous on clinical grounds Neither study individually showed a significant association with food allergy |
No protective effect of BCG vaccination on the development of food allergy 😐 |
|
Bager (2008) [87] Quality: Medium MA+ |
6 Cohort studies Between 1966 & 1 May 2007 |
32,565 children aged 0–17 Populations not defined |
Delivery by C-section |
Food Allergy/Atopy: Hospital admission for food anaphylaxis or epipen prescription (age 0–6) (1 study) Physician diagnosis (age 8–17) (1 study) Parent or self report to foods or drugs (age 3–17) (1 study) Parent or self report to egg, fish or nuts (age 1–2) (1 study) Raised specific IgE to food (age 1–2) (2 studies) |
Food allergy or Food atopy OR 1.32 (95% CI 1.12, 1.55) (6 studies (n = 32,565)) |
C-section may be associated with increases risk of food allergy. ☹ Results may have been affected by publication bias. |
|
Koplin (2008) [88] Quality: Medium MA− |
3 Prospective Cohorts 1 Retrospective cohort Published before July 2007 |
Population based (3) and High Allergy risk (1) 15,121 children |
Delivery by C-Section |
Food Allergy: Symptoms of food allergy Sensitization: IgE antigen-specific levels |
Results were not pooled due to small number of papers included in study | C-section may result in an increased risk of IgE-mediated sensitization ☹ |
☹ = Intervention associated with an increased risk of food allergy or food sensitization; 😐 = Intervention not associated with either increased or decreased risk of food allergy or food sensitization.