Bibian van der Voorn

145 GENDER-SPECIFIC HPA AXIS ACTIVITY IN CHILDHOOD TABLE 1. Summary of studies included in the descriptive analysis. Group First author (year) N (%girls) Age (yr) Sample protocol Assay Result Bias* Saliva <8 yr Klug (2000) 35 119 (46%) 0 3 point day curve Immunoassay No gender differences 2 Eiden (2015) 36 257 (?) 0.75 Laboratory Temperament Assessment Immunoassay No gender differences 3 Plusquellec (2011) 37 466 (?) 1.6 ± 0. 1 Morning sample Immunoassay No gender differences 2 Spinrad (2009) 38 84 (49%) 4.5 Preschool Laboratory Assessment Immunoassay No gender differences 2 Hatzinger (2007) 15 102 (42%) 4.9 ± 0. 4 CAR Immunoassay Cortisol levels were lower in boys at awakening (p<0.1) 1 Saliva 8–18 yr Safarzadeh (2005) 39 100 (58%) 6 – 14 Morning sample Immunoassay No gender differences 1 Isaksson (2015) 40 68 (50%) 9 Morning sample Immunoassay No gender differences 2 Kjölhede (2014) 41 231 (50%) 9.5 ± 1.5 Morning sample Immunoassay No gender differences 1 Vaillancourt (2008) 8 154 (52%) 12.3 ± 0.8 Six samples standardized across time and day Immunoassay On Saturday morning boys had significantly lower morning levels. On Monday and Thursday no gender differences were found. 1 Gunnar (2009) 42 82 (49%) 9 – 15 TSST Immunoassay No gender differences 1 Serum <8 yr Fadalti (1999) 43 72 (49%) 0 – 2 Morning sample Immunoassay No gender differences 0 Ballerini (2010) 44 319 (45%) 0 – 5 Surplus serum Immunoassay No gender differences 2 Parker (1978) 45 106 (43%) 2 – 12 Morning sample Immunoassay No gender differences 2 Serum 8–18 yr Kulasingam (2010) 46 419 (?) 0 – 15 Surplus serum Immunoassay No gender differences 3 Soldin (2005) 47 376 (?) 0 – 18 Surplus serum Immunoassay No gender differences 1 Karbasy (2015) 48 711 (?) 0 – 19 ? Immunoassay No gender differences 1 Fadalti (1999) 43 82 (49%) 6 – 18 Morning sample Immunoassay No gender differences 0 Barra (2015) 49 120 (45%) 12.4 ± 3 Morning sample Immunoassay No gender differences 1 Chalew (1997) 50 15 (73%) 12.7 ± 2.2 24h-blood withdrawal Immunoassay No gender differences 1 Linder (1990) 51 82 (58%) 8 – 17 24h-blood withdrawal HPL No gender differences . 0 Urine <8 yr - Urine 8–18 yr Dorn (1996) 52 20 (55%) 15.2 ± 1.1 24h-urine sample Immunoassay No gender differences 1 * number of high risks of bias out of 4 bias categories (selection, performance, detection and other biases) GENDER-SPECIFIC DIFFERENCES Descriptive analysis Table 1 summarizes the data on the 21 studies included in the descriptive analysis. The majority (90%) of these studies reported no significant gender differences in cortisol levels. Before age 8 yr, one study 15 found significantly lower salivary cortisol levels for boys at awakening. Between ages 8-18 yr, one study 8 found significantly lower morning salivary cortisol levels in boys. Meta-analysis Nine articles (16%) did not report mean and SD values, which were therefore calculated. Figure 3 shows the results of the fixed-effect meta-analysis.