Table 1. Summary of studies of the association between SHS exposure and IBD or pharyngeal bacterial carriage.
| Study (Location, Year) | Design | Setting and Study Population | Sample Size | Exposurea | Case Ascertainmentb | Adjustment in Multivariate Analysis |
| Invasive meningococcal disease | ||||||
| Haneberg et al. (Norway, 1983) [29] | Case-control | Population-based, younger than 12 y | 469 (case 115) | Parental or household smoking | Laboratory-confirmed and/or clinical diagnosis | Only unadjusted ORs reported |
| Stuart et al. (UK, 1988) [40] | Case-control | Population-based, younger than 12 y | 140 (case 70) | Household smoking | Laboratory-confirmed and/or clinical diagnosis | Only unadjusted ORs reported |
| Stanwell-Smith et al. (UK, 1994) [39] | Case-control | Population-based, younger than 5 y | 152 (case 38) | Household smoking | Laboratory-confirmed diagnosis | Only unadjusted ORs reported |
| Fischer et al. (US, 1997) [27] | Case-control | Population-based, younger than 18 y | 259 (case 84) | Maternal smoking at home | Laboratory-confirmed diagnosis | Age, location, maternal education, lack of primary care physician, household member density, school children density, humidifier use, church attendance |
| Moodley et al. (South Africa, 1999) [34] | Case-control | Population-based, younger than 14 y | 280 (case 70) | Two or more household smokers | Laboratory-confirmed and/or clinical diagnosis | Age, breastfeeding, crowding index, recent respiratory tract infection, weight for age z-score |
| Baker et al. (New Zealand, 2000) [25] | Case-control | Population-based, younger than 8 y | 515 (case 202) | Household smoking | Laboratory-confirmed and/or clinical diagnosis | Number of household members, analgesic use, attendance of social gathering, food sharing, household member respiratory tract infection symptom, recent respiratory tract infection, bed sharing |
| Kriz et al. (Czech Republic, 2000) [32] | Case-control | Population-based, younger than 15 y | 203 (case 68) | Number of cigarettes smoked in the house in multiples of 20 | Laboratory-confirmed diagnosis | Mother's and father's education, ownership of car and cottage, crowding |
| Hodgson A, et al. (Ghana, 2001) [30] | Case-control | Population-based, younger than 15 y | 398 (case 201) | Compound (household) smoking | Laboratory-confirmed and/or clinical diagnosis | Only unadjusted ORs reported |
| Robinson et al. (Australia, 2001) [37] | Case-control | Population-based, younger than 16 y | 141 (case 47) | Parent or partner smoking | Laboratory-confirmed and/or clinical diagnosis | Contact with dust, shared bedroom, any illness in prior 2 wk, oral muscle tone deficiency |
| Grein et al. (Ireland, 2001) [28] | Case-control | Population-based, younger than 6 y | 354 (case 87) | Household smoking | Laboratory-confirmed diagnosis | Daycare attendance, number of children under 6 y old in household, number of adults in household, crowding index |
| Sorensen et al. (Denmark, 2004) [38] | Nested case-control | Nationwide population-based, younger than 18 y | 9,702 (case 462) | Maternal smoking at home | ICD-8 and ICD-10 codes (treated as laboratory-confirmed and/or clinical diagnosis) | Low birth weight and prematurity, family income, crowding index |
| McCall et al. (Australia, 2004) [33] | Case-control | Population-based, younger than 6 y | 49 (case 21) | Household smoking | Laboratory-confirmed diagnosis | Breastfeeding, room sharing, daycare attendance |
| Pereiro et al. (Spain, 2004) [36] | Case-control | Hospital-based, younger than 15 y | 424 (case 181) | Household smoking (≥60 cigarettes/day)c | Laboratory-confirmed diagnosis and/or clinical diagnosis | More than four household members, meningococcal vaccination |
| Coen et al. (England, 2005) [26] | Case-control | Population-based, 15–19 y | 288 (case 144) | Latent variable for SHS exposure based on 7 variables | Laboratory-confirmed and/or clinical diagnosis | Socioeconomic status, individual's occupation, meningococcal vaccination status |
| Tully et al. (UK, 2005) [41] | Case-control | Population-based, 15–19 y | 228 (case 114) | Close contacts with smokers | Laboratory-confirmed and/or clinical diagnosis | Only unadjusted ORs reported |
| Honish et al. (Canada, 2008) [31] | Case-control | Population-based, 15–19 y | 132 (case 44) | Maternal smoking | Laboratory-confirmed diagnosis | Use of humidifier, attended rave, bar visits, maternal education, visit to places where smoking was allowed, vaccination status |
| Meningococcal carriage | ||||||
| Stuart et al. (UK, 1989) [58] | Cross-sectional survey | Population-based, 5–19 y | 224 (case 112) | Household smoking | Nasopharyngeal carriage | Only unadjusted ORs reported |
| Kremastinou et al. (Greece, 1994) [55] | Cross-sectional survey | Population-based, 5–19 y | 742 (case 44) | Maternal or other caretaker smoking | Oropharyngeal carriage, saliva | Only unadjusted ORs reported |
| Davies AL, et al. (UK,1996) [54] | Cross-sectional survey | School contacts of index case, 11–18 y | 114 (case 18) | Household smoking | Nasopharyngeal carriage | Only unadjusted ORs reported |
| Kremastinou et al. (Greece, 1999) [56] | Cross-sectional survey | Russian immigrants, 6–15 y | 625 (case 82) | Parental smoking | Oropharyngeal carriage | Only unadjusted ORs reported |
| MacLennan et al. (UK, 2006) [57] | Cross-sectional survey | Population-based, 15–19 y | 13,919 (case 2,319) | Household smoking | Oropharyngeal carriage | Age, active smoking, intimate kissing, pub attendance, number of people in the bedroom, household member density, recent antibiotic use, school type, school size, study sites |
| Invasive pneumococcal disease | ||||||
| Takala et al. (Finland, 1995) [43] | Case-control | Population-based, <15 y | 433 (case 149) | Parental smoking at home | Laboratory-confirmed diagnosis | Only unadjusted ORs reported |
| O'Dempsey et al. (Gambia, 1996) [35] | Case-control | Population-based, 4–14.2 mo | 239 (case 80) | Paternal or other household smoking | Laboratory-confirmed and/or clinical diagnosis | Mother has income, cooking smoke exposure, weight for age z-score, illness in past month, significant illness in past 6 mo |
| Pereiro et al. (Spain, 2004) [36] | Case-control | Hospital-based, younger than 15 y | 306 (case 63) | Household smoking (≥60 cigarettes/day)c | Laboratory-confirmed diagnosis | Only unadjusted ORs reported |
| Haddad et al. (USA, 2008) [42] | Case-control | Population-based, younger than 59 mo | 276 (case 120) | Tobacco exposure (no specific definition provided) | Laboratory-confirmed diagnosis | Only unadjusted ORs reported |
| Pneumococcal carriage | ||||||
| Sung et al. (Hong Kong, 1995) [63] | Cross-sectional survey | Population-based, 2 mo to 5 y | 921 (case 234) | Household smoking | Nasopharyngeal carriage | Only unadjusted ORs reported |
| Coles et al. (India, 2001) [60] | Cross-sectional survey | South India endemic area population, 6 mo | 464 (case 400) | 20 or more cigarettes per day were smoked in the household | Nasopharyngeal carriage | Sex, fed with colostrums, history of night blindness during pregnancy, fuel used for cooking, season, maternal education, transportation with bicycle, number of siblings younger than 5 y, vitamin A supplementation |
| Greenberg et al. (Israel, 2006) [61] | Cross-sectional survey | Population-based, 1–59 mo | 208 (case 143) | Parental smoking at home | Nasopharyngeal carriage | Only unadjusted ORs reported |
| Cardozo et al. (Brazil, 2008) [59] | Cross-sectional survey | Population-based, 10–19 y | 1,013 (case 83) | Household smoking | Nasopharyngeal carriage | Age, sex, presence of siblings younger than 5 y of age, upper respiratory tract infection, acute asthma |
| Labout et al. (Netherlands, 2008) [62] | Cross-sectionald | Population-based, 1.5 mo | 757 (case 337) | Maternal smoking at home | Nasopharyngeal carriage | Birth weight, gestational age, parity, sex, maternal education, having siblings |
| Invasive Hib disease | ||||||
| Cochi et al. (USA, 1986) [45] | Case-control | Population-based, younger than 5 y | 619 (case 89) | Parental smoking | Laboratory-confirmed and/or clinical diagnosis | Only unadjusted ORs reported |
| Harrison et al. (USA, 1989) [3] | Case-control | Population-based, younger than 5 y | 201(Case 74) | Parental smoking | Laboratory-confirmed diagnosis | Sex, race, income, age, maternal education, number of rooms in house, breastfeeding |
| Takala et al. (Finland, 1989) [46] | Case-control | Population-based, 1 month to 6 y | 342 (case 117) | Parental smoking | Laboratory-confirmed diagnosis | Only unadjusted ORs reported |
| Vadheim et al. (USA,1992) [47] | Case-control | Population-based, 18–60 mo | 300 (case 79) | Two or more household smokers | Laboratory-confirmed diagnosis | Age, month of diagnosis, Hib vaccine status, household size, annual household income, number of children under 5 y old, household density breastfeeding, ethnicity, daycare attendance |
| Arnold et al. (USA,1993) [44] | Case-control | Population-based, younger than 6 y | 885 (case 295) | Household smoking | Laboratory-confirmed diagnosis | Daycare attendance, crowding index, number of children under 5 y old, maternal education, annual household income, race |
| Fogarty et al. (Ireland, 1995) [48] | Case-control | Population-based, younger than 14 y | 435 (case 149) | Household smoking | Laboratory-confirmed diagnosis | Social class, bedroom sharing, presence of chronic illness, daycare attendance, youngest in birth order, presence of school age sibling |
| Muhlemann et al. (Switzerland, 1996) [51] | Case-control | Population-based, 2–16 y | 438 (case 102) | Number of household smoker | Laboratory-confirmed and/or clinical diagnosis | Hib vaccination, daycare/kindergarten/school attendance, number of adult household members and siblings, siblings daycare/school attendance, bedroom sharing |
| Silfverdal et al. (Sweden, 1997) [52] | Case-control | Population-based, <6 y | 193 (case 54) | Household smoking | Laboratory-confirmed diagnosis | Socioeconomic status, number of siblings, breastfeeding, daycare attendance, history of chronic allergy or recurrent infection |
| Wolff et al. (USA, 1999) [53] | Case-control | Population-based, <2 y | 176 (case 60) | Parental or caretaker smoking | Laboratory-confirmed diagnosis | Only unadjusted ORs reported |
| Jafari et al. (USA, 1999) [49] | Case-control | Population-based, multistate, 2–16 mo | 133 (case 40) | At least one household smoker | Laboratory-confirmed diagnosis | Only unadjusted ORs reported |
| Pereiro et al. (Spain, 2004) [36] | Case-control | Hospital-based, <5 y | 154 (case 31) | Number of household smokers | Laboratory-confirmed diagnosis | More than four household members, Hib vaccination |
| McVernon et al. (UK, 2008) [50] | Case-control | Population based, <7 y | 428 (case 138) | Household smoking | Laboratory-confirmed diagnosis | Prematurity, breastfeeding, antibiotic use, number of children in nursery, number of siblings, bedroom sharing, single parent household, central heating, home ownership, Hib vaccination |
| Hib carriage | ||||||
| Ayyildiz et al. (Turkey 2003) [64] | Cross-sectional survey | Population based, 7–12 y | 300 (case 9) | Household smoking | Nasopharyngeal carriage | Only unadjusted ORs reported |
| Oguzkaya-Artan et al. (Turkey, 2007) [65] | Cross-sectional survey | Population based, 5–7 y | 683 (case 29) | Household smoking | Oropharyngeal or lower nasopharyngeal carriage | Sex, recent upper respiratory tract infection, number in the household, kindergarten attendance |
a
Individual studies have used different phrasing of exposure metrics. We have used “household smoking” in all cases where the definition was equivalent to smoking by household members or smoking at home.
b
We defined a study as having laboratory-confirmed diagnosis if the study had more than 80% of cases confirmed by a positive culture, rapid antigen test, or PCR-based identification. Other studies were classified as a mix of laboratory-confirmed and clinical diagnosis.
c
The reference category was children with no SHS exposure and the exposed group was divided into multiple categories. The OR for the highest category was used in the meta-analysis. See Results for further information about dose-response.
d
Participants were enrolled in a prospective cohort study but the data for this analysis were from a cross-sectional swab, i.e., no time-to-event analysis.
ICD, International Classification of Diseases.