A reversed gender pattern? A meta-analysis of gender differences in the prevalence of non-suicidal self-injurious behaviour among Chinese adolescents

Table 2 The gender difference in NSSI prevalence by areas

	Number of studies	Men		Women		Odds Ratio	95% CI	Test of heterogeneity
	Number of studies	Events	Total	Events	Total	Odds Ratio	95% CI	Test of heterogeneity
Rural^a	5	3247	13,934	3339	13,277	0.91	0.86,0.96***	Q(4) = 1.01, p = 0.91
Urban^a	8	3669	13,990	3605	14,668	1.01	0.84,1.22	Q(7) = 56.32, p < 0.00001
Hongkong^a	5	1066	8041	2386	12,581	0.58	0.47,0.72***	Q(4) = 21.49, p < 0.0003
Total	18	7982	35,965	9330	40,526	0.84	0.74,0.96*	Q(17) = 189.86, p < 0.00001
Heterogeneity: τ ² = 0.06, χ ² = 189.86, df = 17 (p < 0.00001), I² = 91% Test of overall effect: Z = 2.58 (p = 0.010)
Test for subgroup difference: 0.06, χ ² = 17.35, df = 2 (p = 0.0002), I² = 88.5%

*p < 0.05 for total effect, **p < 0.01 for total effect, ***p < 0.001 for total effect
^a There are one from 19 groups of data among middle school students was excluded because this data included middle schools in both rural and urban areas, but did not provide the separated data

ISSN: 1471-2458