Table 1 Characteristics of studies qualified for meta-analysis
Authors, publication date, (reference) | Design | Country/continent | Age (years) | Asthma definition | Sample size | Year of birth | RRa (95% CIb) | Quality of studies |
|---|---|---|---|---|---|---|---|---|
Xu et al. 2000 [21] | Cohort prospective | Finland/Europe | 7 | Parental questionnaire (diagnosis) | 8088 | 1985–1986 | 1.38 (1.00–1.92) | High |
Nafstad et al. 2000 [22] | Cohort prospective | Norway/Europe | 4 | Questionnaire (diagnosis and symptoms) | 2531 | 1992–1993 | 1.10 (0.70–1.80) | High |
Kero et al. 2002 [8] | Cohort retrospective | Finland/Europe | 7 | 57 years: hospital admissions and medications databases (ICD code); at 7 years: clinical visit (diagnosis) | 59,927 | 1987–1995 | 1.21 (1.08–1.36) | High |
McKeever et al. 2002 [11] | Cohort retrospective | UK/Europe | 0–11 | Parental questionnaire (diagnosis) | 29,238 | 1993–1997 | 1.09 (1.01–1.18) | High |
Bager et al. 2003 [9] | Cohort prospective | Denmark/Europe | < 28 | Interview (diagnosis | 9722 | 1973–1977 | 1.33 (1.02–1.74) | High |
Hakansson et al. 2003 [10] | Cohort retrospective | Sweden/Europe | > 1 | Hospital discharge records (ICD code) | 316,918 | 1984–1996 | 1. 14 (1.07–1.22) | High |
Maitra et al. 2004 [12] | Cohort prospective | UK/Europe | 5–8 | Parental questionnaire (diagnosis) | 12,367 | 1991–1992 | 1.16 (0.90–1.50) | High |
Smith et al. 2004 [23] | Cohort retrospective | Scotland/Europe | 8–9 | Hospital admissions (ICD code) | 241,846 | 1992–1995 | 1.10 (1.00–1.20) | High |
Renz-polster et al. 2005 [24] | Cohort prospective | US/USA | 3–10 | Medical records (diagnosis) | 8953 | 1990–1992 | 1.24 (1.01–1.57) | High |
Bernsen et al. 2005 [25] | Cohort retrospective | Netherlands/Europe | > 6 | Medical records (diagnosis) | 1961 | 1988–1990 | 1.03 (0.51–2.08) | High |
Juhn et al. 2005 [26] | Cohort retrospective | UK/Europe | 7 | Medical records (diagnosis or symptoms) | 7106 | 1976–1982 | 0.93 (0.60–1.40) | High |
Delbey et al. 2005 [27] | Case–control retrospective | Washington/USA | 6–12 | Hospital admissions (ICD code) | 10,320 | – | 1.20 (1.04–1.39) | High |
Salam et al. 2006 [28] | Cohort retrospective | US/USA | < 18 | Parental questionnaire (diagnosis) | 6259 | 1975–1987 | 1.33 (1.01–1.75) | High |
Werner et al. 2007 [29] | Cohort prospective | Danish/Europe | 15–18 | Parental questionnaire (diagnosis) | 7119 | 1984–1987 | 1.11 (0.88–1.39) | High |
Roduit et al. 2008 [30] | Cohort prospective | Netherlands/Europe | 8 | Parental questionnaire (diagnosis) | 2917 | 1996–1997 | 1.79 (1.27–2.51) | High |
Pistiner et al. 2008 [31] | Cohort prospective | US/USA | 9 | Parental questionnaire (diagnosis) | 432 | 1994–1996 | 1.10 (0.60–2.30) | Moderate |
Tollnes et al. 2008 [32] | Cohort retrospective | Norway/Europe | 18 | Parental questionnaire (diagnosis) | 1,869,380 | 1967–1998 | 1.52 (1.42–1.62) | High |
Metsala et al. 2008 [33] | Cohort retrospective | Finland/Europe | > 3 | Hospital admissions (ICD code) | 22,548 | 1996–2004 | 1.15 (1.05–1.25) | High |
Mohammadzadeh et al. 2009 [34] | Case–control retrospective | Iran/Asia | 3–14 | Hospital admissions (ICD code) | 512 | – | 1.20 (0.80–1.70) | Moderate |
Devidson et al. 2010 [35] | Cohort retrospective | UK/Europe | 2–11 | Hospital admissions (ICD code) | 248,612 | 1970–1989 | 1.18 (1.02–1.34) | High |
Park et al. 2010 [36] | Cohort retrospective | Korea/Asia | ≤ 16 | Questionnaire (diagnosis and Symptoms) | 279 | 2003 | 0.76 (0.37–1.57) | Moderate |
Nimwegen et al. 2011 [37] | Cohort prospective | Netherlands/Europe | 6–7 | Parental questionnaire (diagnosis) | 2343 | 2002 | 0.89 (0.50–1.56) | High |
Magnus et al. 2011 [38] | Cohort prospective | Norway/Europe | 3 | Parental questionnaire (diagnosis) | 37,171 | 1999–2008 | 1.15 (1.02–1.29) | High |
Nathan et al. 2011 [39] | Case–control retrospective | Malaysian/Asia | 3–15 | Hospital admissions (ICD code) | 156 | – | 1.17 (0.47–2.91) | Moderate |
Almqvist et al. 2012 [40] | Cohort retrospective | Sweden/Europe | > 10 | National patient register (ICD code) | 87,500 | 1993–1999 | 1.20 (1.05–1.37) | High |
Hancox et al. 2012 [41] | Cohort retrospective | New Zealand/Oceania | 13 | Hospital admissions (ICD code) | 1037 | 1972–1973 | 0.92 (0.32–2.65) | High |
Kolokotroni et al. 2012 [42] | Cross-sectional | Cyprus/Europe | 8 | Parental questionnaire (diagnosis) | 2216 | – | 1.41 (1.09–1.83) | High |
Braback et al. 2013 [43]** | Cohort retrospective | Sweden/Europe | 2–5 | Swedish prescribed Drug Register (Antiasthmatic drugs) | 199,837 | 1999–2006 | 1.20 (1.13–1.28) | High |
Braback et al. 2013 [43]** | Cohort retrospective | Sweden/Europe | 6–9 | Swedish prescribed Drug Register (Antiasthmatic drugs) | 199,837 | 1999–2006 | 1.18 (1.09–1.27) | High |
Guibas et al. 2013 [44] | Cross-sectional | Aetoloakarnania/Europe | 9–13 | Hospital admissions (ICD code) | 2572 | – | 1.39 (1.04–1.87) | High |
Van Berkel et al. 2015 [51] | Cohort prospective | Netherlands/Europe | 6 | Questionnaire (diagnosis) | 6128 | – | 1.09 (0.76–1.55) | High |
Black et al. 2016 [45] | Cohort retrospective | UK, Scotland/Europe | 5 | Hospital admissions (ICD code) | 40,145 | 1993–2007 | 1.11 (0.99–1.25)* | High |
Kristensen et al. 2016 [52] | Cohort | Denmark/Europe | 0–14 | Hospital admissions (ICD code) | 750,569 | 1997–2012 | 1.12 (1.09–1.50) | High |
Sevelsted et al. 2016 [53] | Cohort prospective | Denmark/Europe | 0–15 | – | 864,049 | 1997–2010 | 2.18 (1.27–3.73) | High |
Lavin et al. 2017 [46]** | Cohort prospective | India/Asia | 8 | Questionnaire (diagnosis) | 2026 | 2001–2002 | 2.60 (1.30–5.40) | High |
Lavin et al. 2017 [46]** | Cohort prospective | Vietnam/Asia | 8 | Questionnaire (diagnosis) | 2000 | 2001–2002 | 2 (1.20–3.30) | High |
Chu et al. 2017 [54] | Case–control retrospective | China/Asia | 4–12 | Questionnaire (diagnosis) | 1385 | 2015–2016 | – | High |
Brix et al. 2017 [47] | Cohort retrospective | Denmark/Europe | 0–15 | (ICD code) | 928 | 1997–2012 | – | High |
Rusconi et al. 2017 [55] | Cohort retrospective | European/Europe | 5–9 | Questionnaire (diagnosis | 67,613 | 1996–2006 | 1.22 (1.02–1.46) | High |