a nonsignificant trendp = 0.08
The unadjusted results of multilevel linear growth model analyses similarly indicated stable headache frequency over time, on average ( b = 0.001 ± 0.002, t = −0.087, p = 0.93), and a nonsignificant trend of decreasing headache intensity over time ( b = −0.06 ± 0.03, t = −0.1.76, p = 0.08).