The relationship between headache-attributed disability and lost productivity: 2. Empirical evidence from population-based studies in nine disparate countries

Table 13 Linear regressions between impairment¹ and lost paid worktime, lost household worktime and total lost productivity attributed to migraine by country

Country	HALT question 1 + 2			HALT question 3 + 4			HALT questions 1 + 2 + 3 + 4
Country	R²	Equation	p	R²	Equation	p	R²	Equation	p
China	0.11	Y = 0.15x + 3.4	< 0.001	0.13	Y = 0.18x + 4.1	< 0.001	0.14	Y = 0.32x + 7.6	< 0.001
Ethiopia	0.01	Y = 0.03x + 2.1	0.03	0.09	Y = 0.12x + 1.8	< 0.001	0.09	Y = 0.14x + 3.9	< 0.001
India	0.14	Y = 0.07x + 0.6	< 0.001	0.05	Y = 0.05x + 2.0	< 0.001	0.16	Y = 0.12x + 2.6	< 0.001
Lithuania + Luxembourg	0.03	Y = 0.06 + 1.4	< 0.001	0.13	Y = 0.14x + 1.7	< 0.001	0.12	Y = 0.19x + 3.0	< 0.001
Nepal	0.00	Y = 0.01x + 1.9	0.53	0.06	Y = 0.09x + 2.4	< 0.001	0.04	Y = 0.10x + 4.3	< 0.001
Pakistan	0.01	Y = 0.05x + 7.2	0.05	0.05	Y = 0.15x + 9.1	< 0.001	0.08	Y = 0.22x + 11.3	< 0.001
Russia	0.02	Y = 0.02x + 1.9	0.15	0.05	Y = 0.04x + 3.2	0.03	0.05	Y = 0.06x + 5.1	0.03
Spain	0.16	Y = 0.13x + 2.8	< 0.001	0.22	Y = 0.20x + 2.9	< 0.001	0.20	Y = 0.30x + 5.6	< 0.001

HALT: Headache-Attributed Lost Time questionnaire. ¹ Calculated as proportion of time in ictal state*reported usual headache intensity; significant p-values are emboldened.

ISSN: 1129-2377