Figure 1
Meta-analysis of the relative risk, or odds ratio, for the association between striking life events and primary breast cancer incidence. Solid squares represent risk estimates for the individual studies, with the size of the squares proportional to the sample size and the number of events. Horizontal lines denote 95% confidence intervals (CIs). The diamond shows the confidence interval for the pooled relative risks. Positive values indicate an increased relative risk for primary breast cancer development. Test for overall effect: Z = 2.99, P < 0.01; chi-square test for heterogeneity = 80.53, degrees of freedom = 6, P < 0.001; I2 = 93%.