Depression and risk of transformation of episodic to chronic migraine

Table 2 Multivariate predictors of chronic migraine onset in persons with EM the year prior to onset

Predictive factors	Model 1 OR (95 % CI)^a	Model 2 OR (95 % CI)^b
Age	0.99 (0.98–1.01)	1.00 (0.99–1.01)
Gender	0.75 (0.37–1.51)	1.03 (0.71–1.50)
Income	0.90 (0.74–1.09)	0.85 (0.76–0.95)*
Insurance	0.82 (0.41–1.61)	0.89 (0.61–1.29)
BMI (linear)	0.91 (0.80–1.04)	0.91 (0.85–0.96)*
BMI (quadratic)	1.00 (1.00–1.00)	1.00 (1.00–1.00)*
Cutaneous allodynia		1.04 (0.76–1.41)
SRPD-anxiety		1.31 (0.94–1.84)
Pain intensity (≥4)		2.18 (0.67–7.13)
Headache frequency (days/month)		1.29 (1.21–1.36)*
Migraine symptom score		1.06 (1.01–1.11)*
Anti-depressant use		1.35 (0.95–1.91)
Medication overuse		1.79 (1.26–2.54)*
Depression (PHQ-9)^c	3.22 (1.65–6.25)*	1.65 (1.12–2.45)*

Values are OR, 95 % CI. N = 304 (2.27 %) events out of 13,372 trials and 97.73 % non-events for both models
* Indicates that data are significant at the p < 0.05 level or below
^aModel 1: adjusted for age (continuous), gender (binary, reference = male), income (linear trend in cumulative categories), health insurance status (binary, reference = uninsured), and BMI (continuous and quadratic)
^bModel 2: adjusted for sociodemographics and for cutaneous allodynia (binary, diagnosis defined as score >3, SRPD-anxiety (binary, with no SRPD-anxiety endorsement as reference), anti-depressant use (binary, reference = no use), medication overuse proxy (binary, reference = no overuse), headache pain intensity (binary, no/mild pain (scores 0–3) versus combination of moderate (scores 4–6), moderately severe (scores 7–8), severe (scores 9–10), migraine symptom score (continuous), and headache frequency (headache days/month)
^cDepression (PHQ-9) = dichotomous definition defined by a PHQ-9 cut score ≥15

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