Table 2. Clinical characteristics and univariable ORs for neuroimaging abnormalities and serious neuroimaging abnormalities.

	Neuroimaging abnormalities				Serious neuroimaging abnormalities
	Normal (n=757)	Neuroimaging abnormalities (n=170)	OR (95% CI)	p	Normal and nonserious neuroimaging abnormalities (n=893)	Serious neuroimaging abnormalities (n=34)	OR (95% CI)	p
Age ≥40 years	491 (64.9)	155 (91.2)	5.59 (3.22–9.70)	<0.001	616 (69.0)	30 (88.2)	3.37 (1.17–9.66)	0.024
Male sex	267 (35.3)	80 (47.1)	1.63 (1.16–2.28)	0.004	333 (37.3)	14 (41.2)	1.17 (0.58–2.36)	0.646
Visit route
Self-referral	465 (61.4)	112 (65.9)	Reference		558 (62.5)	19 (55.9)	Reference
Referred by doctor	293 (38.6)	58 (34.1)	0.82 (0.58–1.16)	0.279	335 (37.5)	15 (44.1)	1.31 (0.65–2.62)	0.437
Age ≥50 years at headache onset	224 (29.6)	97 (57.1)	3.16 (2.24–4.44)	<0.001	306 (34.3)	15 (44.1)	1.51 (0.75–3.02)	0.239
Headache duration ≥1 year	247 (32.6)	67 (39.4)	1.34 (0.95–1.89)	0.092	300 (33.6)	14 (41.2)	1.38 (0.68–2.77)	0.361
Severe headache intensity, VAS score ≥7	398 (52.6)	70 (41.2)	0.63 (0.45–0.88)	0.008	453 (50.7)	15 (44.1)	0.76 (0.38–1.52)	0.450
Medication overuse	46 (6.1)	13 (7.6)	1.28 (0.67–2.42)	0.449	59 (6.6)	0 (0.0)	NA
Headache classification
Migraine	396 (52.3)	58 (34.1)	Reference		439 (49.2)	15 (44.1)	Reference
Tension-type headache	216 (28.5)	82 (48.2)	2.59 (1.78–3.77)	<0.001	284 (31.8)	14 (41.2)	1.44 (0.68–3.03)	0.334
Trigeminal autonomic cephalalgias	14 (1.8)	1 (0.6)	0.48 (0.06–3.77)	0.492	15 (1.7)	0 (0.0)	0.86 (0.30–2.40)*	0.775
Other primary headache disorders	131 (17.3)	29 (17.1)	1.51 (0.92–2.46)	0.097	155 (17.4)	15 (14.7)

Data are n (%) values except where indicated otherwise.

^*OR of trigeminal autonomic cephalalgias plus other primary headache disorders for significant neuroimaging abnormalities.

CI: confidence interval, NA: not applicable, OR: odds ratios, VAS: visual analog scale.