a trend towards significancep < 0.002
However, the correlations between IL-6 and headache (r = 0.572, p = 0.017) and between IL-6 and concentration problems (r = 0.536, p = 0.027) showed a trend towards significance (taking into account multiple comparisons, a conservative p -value cut-off was applied for statistical significance, which was set at p < 0.002).