Hygiene hypothesis: association between hygiene and asthma among preschool children in Lebanon

Abstract

Objectives: To validate a scale to assess the hygiene hypothesis and the association between hygiene and asthma among Lebanese preschool children aged 3–5 years. Methods: This cross-sectional study, conducted between November 2018 and March 2019, enrolled 515 preschool children. Asthma and potential risk factors, including hygiene, were assessed using a standardized questionnaire. A specific hygiene hypothesis scale has been gen-erated and validated for this purpose. Results: The hygiene hypothesis scale items converged over a solution of nine factors that had an Eigenvalue over 1, explaining a total of 65.86% of the variance. An acceptable Cronbach’s alpha value was recorded for the hygiene hypothesis scale (0.696). Variables correlated with higher odds of asthma were male gender (ORa = 0.41 for females), living near a prairie sprayed with pesticides (ORa = 3.09), having a heating system in the bedroom compared to the sitting room (ORa = 9.97), attending kindergarten (ORa = 2.80), having a mother who smokes water-pipe compared to not smoking (ORa = 3.34), having a mother with a history of asthma (ORa = 5.50), and having respiratory infections (ORa = 14.72). However, the hygiene hypothesis score was not associated with higher odds of asthma (p = 0.881). Conclusions: The current results suggested that neither home cleaning nor personal cleanliness was correlated with asthma in preschool children. Larger prospective studies that measure the intensity and duration of exposure to each toxicant are suggested to better assess the hygiene hypothesis items and their association with asthma.

Risk factors of asthma in the Asian population: a systematic review and meta-analysis

“…Further, we also identified 9 common asthma comorbidities that were reported in at least 3 studies. These include atopy (26 studies) [ 16 – 41 ], allergic rhinitis (AR, 21 studies) [ 19 , 26 , 35 , 42 – 59 ], respiratory infections (20 studies) [ 27 , 40 , 44 , 49 , 57 , 59 – 73 ], eczema/atopic dermatitis (AD, 18 studies) [ 40 , 44 , 45 , 47 , 53 – 59 , 62 , 70 , 72 , 74 – 79 ], gastroesophageal reflux disease (5 studies) [ 19 , 44 , 47 , 67 , 80 ], chronic rhinosinusitis (5 studies) [ 19 , 57 , 76 , 81 , 82 ], food allergy (4 studies) [ 26 , 62 , 76 , 82 ], otitis (3 studies) [ 67 , 76 , 82 ], and bronchitis (3 studies) [ 44 , 57 , 83 ] (Table S 6 ).…”

“…Overall, 91 studies in Asia investigated the associations between the family history of various allergy-related diseases and the risk of asthma development [ 20 , 22 , 23 , 25 – 27 , 31 , 32 , 34 – 36 , 42 , 44 – 46 , 51 , 52 , 57 , 59 , 62 , 65 – 68 , 70 – 73 , 76 – 79 , 82 – 140 ]. Among these, the family medical history of asthma (any family members) was most frequently studied and significantly associated with an increased risk of asthma (36 studies) [ 20 , 25 – 27 , 32 , 34 , 35 , 44 – 46 , 51 , 57 , 59 , 76 , 77 , 79 , 82 , 83 , 86 , 95 , 101 , 102 , 104 – 106 , 108 – 110 , 112 , 116 , 123 , 128 , 129 , 133 , 137 , 140 , 141 ].…”

“…S 1 ). Further, we also performed meta-analyses for the family medical history of asthma in specific family groups separately, including paternal asthma (11 studies) [ 26 , 27 , 62 , 68 , 92 , 113 , 114 , 117 , 119 , 120 , 138 ], maternal asthma (15 studies) [ 26 , 27 , 62 , 68 , 73 , 84 , 89 , 92 , 113 , 117 , 119 , 120 , 123 , 134 , 138 ], parental asthma (9 studies) [ 26 , 66 , 72 , 78 , 88 , 93 , 118 , 121 , 122 ], and sibling’s asthma (4 studies) [ 26 , 65 , 123 , 138 ]. The combined risk estimates for asthma were also significantly increased in these four meta-analyses (pooled OR ranged between 3.22 and 4; Fig.…”

“…A total of 76 studies have investigated housing-related factors and their association with asthma [ 16 – 18 , 25 , 26 , 38 , 52 , 53 , 58 – 60 , 67 , 72 , 73 , 79 , 82 , 85 , 88 , 91 , 94 , 95 , 97 , 98 , 105 , 111 , 118 – 120 , 125 , 127 , 129 , 130 , 135 , 136 , 138 , 142 – 182 ]. In these studies, frequently investigated housing-related risk factors of asthma included household dampness (18 studies) [ 17 , 67 , 72 , 82 , 85 , 88 , 125 , 130 , 142 , 143 , 146 , 147 , 150 , 157 , 166 , 171 , 174 , 180 ], traffic pollution (14 studies) [ 16 , 18 , 53 , 58 , 127 , 129 , 130 , 135 , 148 , 149 , 172 , 173 , 176 , 181 ...…”

“…The association between gender and asthma was reported in 75 studies [ 16 , 18 , 19 , 21 , 22 , 33 , 35 , 37 , 38 , 40 , 42 , 43 , 47 , 49 , 56 , 58 , 62 , 67 , 70 , 71 , 73 , 74 , 79 , 82 – 87 , 92 , 93 , 95 , 97 , 99 , 104 , 105 , 107 , 110 , 116 , 118 , 120 , 122 , 124 – 127 , 130 , 131 , 133 , 135 – 137 , 139 , 142 , 159 , 170 , 179 , 184 – 201 ]. Of these, 58 studies have observed male subjects having a higher asthma susceptibility as compared with that of the female subjects significantly [ 16 , 18 , 22 , 37 , 38 , 40 , 47 , 56 , 58 , 62 , 67 , 70 , 71 , 73 , 74 , …”