Table 6

Bivariate analyses of active headache disorders according to methodological aspects of studies

		Headache (183 studies)		Migraine (244 studies)		TTH (110 studies)		H15+ (59 studies)
Correlations		r	p	r	p	r	p	r	p
Year of publication		0.09	0.22	0.30	< 0.0005	−0.03	0.8	0.20	0.14
Number (ln transformed) of participants		−0.27	< 0.001	−0.26	< 0.001	−0.17	0.07	−0.33	0.01
Participating proportion (9 categories)		0.11	0.15	0.02	0.7	−0.11	0.2	−0.02	0.9
Age (mid-range value) (years)		−0.14	0.05	0.03	0.6	0.13	0.2	0.14	0.3
Summed quality score		0.03	0.7	−0.02	0.8	− 0.02	0.8	0.00	1.0
Means of reported prevalences (%)		Mean (SD, N)		Mean (SD, N)	p	Mean (SD, N)	p	Mean (SD, N)	p
Populationa	General/schools	51.9 (22.7, 142)	1.0	13.5 (8.4, 177)	0.2	26.5 (17.0, 85)	0.6	4.8 (3.1, 54)	0.2
	Selected	52.2 (22.7, 41)		15.5 (11.1, 66)		24.4 (21.1, 25)		3.0 (2.1, 5)
Health-care personnelb	No	50.2 (25.4, 33)	0.3	13.4 (9.1, 52)	0.03	23.3 (22.9, 19)	0.7	3.0 (2.1, 5)	–
	Yes	60.0 (22.9, 8)		23.0 (14.7, 15)		27.8 (15.2, 6)		–
Sampling methodc	Random	54.7 (23.2, 44)	0.4	12.8 (8.1, 184)	0.002	25.7 (18.6, 83)	0.8	4.5 (3.2, 51)	0.4
	Not random	51.1 (23.1, 139)		18.0 (11.4, 60)		26.8 (16.0, 27)		5.5 (2.1, 8)
Mode of engagementd	Telephone/face-to face	50.8 (23.6, 95)	0.5	13.1 (8.8, 136)	0.07	26.3 (18.7, 66)	0.8	5.5 (3.5, 32)	0.02
	Questionnaire	53.2 (22.6, 88)		15.3 (9.8, 108)		25.5 (17.0, 44)		3.6 (2.0, 27)
Validation of diagnostic methode	Yes	51.2 (24.3, 93)	0.7	14.3 (10.3, 107)	0.7	25.6 (18.0, 56)	0.8	4.6 (3.2, 41)	0.9
	No	52.8 (22.1, 90)		13.8 (8.5, 137)		26.(18.0, 54)		4.7 (2.6, 18)
dMig and pMigf	Yes	55.4 (20.8, 46)	0.3	19.2 (9.9, 59)	< 0.001	27.6 (15.9, 41)	0.5	5.6 (3.9, 22)	0.1
	No	50.8 (23.9, 137)		12.4 (8.5, 185)		25.0 (19.1, 69)		4.1 (2.2, 37)
dTTH and pTTHg	Yes	61.5 (17.8, 29)	0.02	20.0 (10.3, 32)	< 0.001	29.5 (13.7, 33)	0.2	6.2 (4.1, 18)	0.04
	No	50.2 (23.7, 154)		13.1 (8.8, 212)		24.5 (19.4, 77)		3.9 (2.2,41)
Number of conditionsh	Only headaches	52.9 (23.0, 173)	0.02	14.3 (9.3, 235)	0.04	26.0 (18.0, 110)	–	4.6 (3.0, 59)	–
	Including other conditions	35.2 (20.4, 10)		7.8 (5.6, 9)		–
Type of screening question	Neutral	61.8 (22.0, 58)	< 0.0005	17.1 (9.3, 65)	0.006	31.9 (22.5, 42)	0.02	5.0 (2.1, 24)	0.8
	Unknown	50.8 (23.7, 71)		12.9 (10.0, 111)		23.0 (14.2, 41)		4.3 (2.4, 16)
	Severity qualification	41.8 (19.1, 52)		12.7 (6.6, 66)		20.9 (12.1, 26)		4.4 (4.5, 18)

TTH tension-type headache, H15+ headache on ≥15 days/month, r Pearson’s r, p two-tailed p-value (Pearson’s r, independent-samples Student’s t-test, or one-way ANOVA for screening question), SD standard deviation, N number of studies

^aGeneral population, community-based sample or obligatory schools versus selected populations (among workplace employees, college students, health-plan members etc)

^bAmong selected populations: medical students, hospital staff or neurologists versus other selected populations 

^cRandom sampling versus non-random sampling or failure to obtain random sample

^dTelephone or face-to face interview versus self-administered questionnaire or not specified

^eEffort at validating versus none or unstipulated

^fStudies distinguishing between dMig and pMig and reporting both versus those not

^gStudies distinguishing between dTTH and pTTH and reporting both versus those not

^hStudies restricted to headache (or migraine, TTH etc) versus studies investigating multiple other disorders (neurological, other pain conditions etc)