. 2011 Jan 5;12(3):315–322. doi: 10.1007/s10194-010-0285-1

Table 3.

The influence of baseline predictors of outcome at 4-years follow-up expressed by p values evaluated by non-parametric tests

Predictors	Headache days/month	Headache index/month	Medication days/month	Responders	MOH
Predictors	p value	p value	p value	p value	p value
Male	0.019^b	0.035^b	0.051^b	0.14^a	0.18^a
Age	0.85^c (0.03)	0.65^c (0.07)	0.86^c (0.03)	0.22^b	0.56^b
Years with headache	0.03^c (0.31)	0.18^c (0.19)	0.04^c (0.29)	0.23^b	0.045^b
Type of intervention (3 groups)	0.41^b	0.84^b	0.73^b	0.85^a	0.36^a
>2 preventive drugs	0.63^b	0.71^b	0.19^b	0.52^a	0.42^a
MCS-12	0.41^c (0.12)	0.26^c (0.16)	0.67^c (0.06)	0.31^b	0.46^b
PCS-12	0.04^c (0.29)	0.027^c (0.31)	0.007^c (0.38)	0.10^b	0.19^b
HADS-anxiety	0.04^c (0.29)	0.0125^c (0.32)	0.14^c (0.21)	0.004^b	0.15^b
HADS-depression	0.06^c (0.26)	0.0136^c (0.30)	0.057^c (0.27)	0.012^b	0.22^b
HADS-total	0.027^c (0.31)	0.013^c (0.35)	0.056^c (0.27)	0.003^b	0.17^b
Type of drug overused	0.52^b	0.28^b	0.51^b	0.91^a	0.77^a
Headache diagnosis^d	0.02^b	0.006^b	0.12^b	0.027^a	0.82^a
Employed, full-time or part-time	0.08^b	0.06^b	0.25^b	0.14^a	0.18^a
≤9 years of education	0.82^b	0.32^b	0.06^b	0.54^a	0.04^a
Surgery during follow-up	0.42^b	0.18^b	0.26^b	0.83^a	0.59^a

^aChi square test

^bKruskal–Wallis test

^cSpearman’s rho with correlation coefficient in brackets

^dThe original headache before they developed MOH at baseline: 18 subjects had pure migraine, 17 tension-type headache without migrainous features, and 15 mixed headache