Income dissatisfaction and migraine headache. Evidence from a nationwide population-based survey

Figures & data

Table 1. Mean values of the variables used in the estimations.

Variable	Migraineurs	No-Migraineurs	Test of the difference between means P-Value
INCOME_DISSAT (1–4)	2.48	2.39	0.0000
AGE (IN YEARS)	51.82	52.32	0.0067
FEMALE	64.65%	42.46%	0.0000
HIGHEDU	12.80%	13.28%	0.1834
MARRIED	59.31%	58.28%	0.0499
SOUTH	36.79%	34.57%	0.0000
ITACIT	95.86%	94.05%	0.0000
ASTHMA	8.28%	3.99%	0.0000
ALLERGY	22.14%	10.20%	0.0000
CELIAC	0.89%	0.38%	0.0000
HEART_PRO	7.13%	4.49%	0.0000
STROKE	2.26%	1.56%	0.0000
BULIMIA	1.42%	0.33%	0.0000
THYROID	11.63%	5.12%	0.0000
DEPRESSION	13.98%	3.58%	0.0000
ANXIETY	10.02%	2.38%	0.0000

For the description of variables see Table A1. H0: Equal mean among groups.

Table 2. The impact of income dissatisfaction on migraine.

	1	2	3	4	5	6
INCOME_DISSAT	0.0970***	0.1086***	0.0745***	0.0945***	0.1041***	0.0690***
	0.0231	0.0345	0.0165	0.0238	0.0358	0.0171
AGE	0.0043***	0.0041***	0.0045***	0.0037***	0.0036***	0.0040***
	0.0005	0.0005	0.0005	0.0005	0.0006	0.0005
AGE2	−0.0000***	−0.0000***	−0.0000***	−0.0000***	−0.0000***	−0.0000***
	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000
FEMALE	0.1087***	0.1105***	0.1091***	0.0816***	0.0840***	0.0823***
	0.0028	0.0027	0.0026	0.0029	0.0029	0.0028
MARRIED	0.0138***	0.0148***	0.0115***	0.0186***	0.0193***	0.0164***
	0.0035	0.0042	0.0031	0.0034	0.0040	0.0031
SOUTH	0.0000	0.0003	0.0348***	−0.004	−0.0036	0.0259***
	0.0045	0.0058	0.0079	0.0046	0.0060	0.0080
ITACIT	0.0778***	0.0772***	0.0696***	0.0631***	0.0625***	0.0546***
	0.0088	0.0102	0.0078	0.0091	0.0107	0.0080
INCOME	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000
	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000
EMPLOYED	0.0249***	0.0281***	0.0213***	0.0356***	0.0382***	0.0312***
	0.0061	0.0078	0.0052	0.0061	0.0078	0.0052
ASTHMA				0.0509***	0.0508***	0.0523***
				0.0066	0.0068	0.0065
ALLERGY				0.0940***	0.0934***	0.0940***
				0.0042	0.0043	0.0042
CELIAC				0.0347*	0.0349*	0.0362*
				0.0200	0.0200	0.0198
HEART_PRO				0.0345***	0.0342***	0.0356***
				0.0065	0.0068	0.0064
ICTUS				0.0173	0.0173	0.0198*
				0.0106	0.0107	0.0104
BULIMIA				0.1284***	0.1275***	0.1346***
				0.0207	0.0210	0.0204
THYROID				0.0654***	0.0651***	0.0648***
				0.0056	0.0057	0.0056
DEPRESSION				0.1424***	0.1412***	0.1468***
				0.0083	0.0093	0.0077
ANXIETY				0.1324***	0.1319***	0.1352***
				0.0091	0.0096	0.0088
Observations	72,520	72,520	72,520	63,489	63,489	63,489
R-2	0.0173	0.0121	0.0264	0.0487	0.0435	0.0607
AIC	48964.23	49340.87	48300.51	35338.8	35678.42	34540.55
First stage chi2	606.22	276.65	1172.19	518.36	233.57	988.25
First stage chi2 (p)	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000
Fixed Effect	Sector	Job Position	Region	Sector	Job Position	Region

For the description of variables see Table A1. The dependent variable is MIGRAINE. Superscripts ***, ** and * denote statistical significance at the 1, 5 and 10 percent level, respectively. The standard errors (in italics) are robust to heteroskedasticity and autocorrelation.

Table 3. The impact of income dissatisfaction on migraine by job position.

	1	2	3	4	5	6	7	8	9	10	11
INCOME_DISSAT	−0.0658	0.4743**	0.1060**	−0.0584	0.1522	0.2712	−0.0434	0.1387*	0.2471***	0.2641	0.0524
	0.1078	0.2391	0.0501	0.1415	0.2172	0.3852	0.2104	0.0734	0.0857	0.3226	0.3650
AGE	0.0045	0.0080**	0.0062***	0.0057***	0.0077	0.0062	0	0.0057**	−0.0008	−0.0002	0.0021
	0.0039	0.0034	0.0010	0.0016	0.0060	0.0135	0.0036	0.0028	0.0016	0.0125	0.0031
AGE2	−0.0001	−0.0001*	−0.0001***	−0.0001***	−0.0001	0.0000	0.0000	−0.0001*	0.0000	0.0000	0.0000
	0.0000	0.0000	0.0000	0.0000	0.0001	0.0002	0.0000	0.0000	0.0000	0.0001	0.0000
FEMALE	0.0615***	0.1029***	0.1098***	0.1107***	0.0634***	0.2358***	0.0915***	0.0998***	0.1040***	0.2262***	0.0782***
	0.0203	0.0160	0.0050	0.0053	0.0239	0.0835	0.0216	0.0148	0.0085	0.0470	0.0214
MARRIED	−0.0537***	0.0213	0.0214***	−0.001	0.0495	0.0081	−0.0052	0.009	0.0179*	0.0367	0.0335
	0.0197	0.0166	0.0071	0.0149	0.0495	0.0779	0.0216	0.0134	0.0109	0.1063	0.0280
SOUTH	0.0021	−0.0321	−0.0175**	0.0414	−0.0895	0.0205	0.0434*	−0.0223*	−0.0111	0.0622	0.0691**
	0.0163	0.0199	0.0071	0.0296	0.0587	0.0831	0.0261	0.0123	0.0174	0.0462	0.0317
ITACIT	−0.0259	0.0834	0.0918***	0.027	0.094	0.0052	0.1160***	0.0045	0.1033***	0.2083*	0.0635
	0.0771	0.0594	0.0194	0.0390	0.0776	0.1723	0.0254	0.0502	0.0298	0.1250	0.0781
EMPLOYED	0.0227	0.0908***	0.0171	−0.0111	−0.01	0.2186	−0.005	0.0233	0.0698***	0.1269	0.0255
	0.0266	0.0335	0.0112	0.0304	0.0276	0.2806	0.0788	0.0278	0.0229	0.1017	0.0604
Observations	1,469	2,916	20,102	29,893	923	128	1,655	2,984	10,051	375	2,024
R-2	0.01	0.034	0.018	0.006	0.045	0.008	0.03	0.02	0.02	0.11	0.028
Sample	Manager	Management	Employee	Subordinate worker	Apprentice	Home worker on behalf of a company	Entrepreneur (with at least one employee)	Freelance	Self-employed worker	Member of a cooperative for the production of goods and services	Family assistant

For the description of variables see Table A1. The dependent variable is MIGRAINE. Superscripts ***, ** and * denote statistical significance at the 1, 5 and 10 percent level, respectively.The standard errors (in italics) are robust to heteroskedasticity and autocorrelation.

Table A1. Description and summary statistics of the variables used in the estimations.

VARIABLE	DESCRIPTION	Mean	StdD	Min	Max	Obs
INCOME_DISSAT	Level of economic dissatisfaction of the individual	2.40	0.62	1	4	80,091
MIGRAINE	Dummy equal to one if the individual is affected by migraine, zero otherwise	0.14	0.34	0	1	74,921
AGE	Age of the individual	52.50	17.16	15	90	80,091
FEMALE	Dummy equal to one if the individual is a female, zero otherwise	0.463	0.499	0	1	80,091
HIGHEDU	Dummy equal to one if the individual is higher educated, zero otherwise. See table notes.	0.132	0.338	0	1	80,091
MARRIED	Dummy equal to one if the individual is married, zero otherwise	0.58	0.49	0	1	80,091
SOUTH	Dummy equal to one if the individual is resident in the southern part of Italy, zero otherwise	0.35	0.48	0	1	80,091
ITACIT	Dummy equal to one if the individual is an Italian citizen, zero otherwise	0.94	0.23	0	1	80,091
INCOME	Hour wage per job position in euro	31.44	99.85	9.45	723.00	77,499
EMPLOYED	Dummy equal to one if the individual is employed, zero otherwise	0.53	0.50	0	1	80,091
ASTHMA	Dummy equal to one if the individual is affected by asthma, zero otherwise	0.05	0.21	0	1	77,707
ALLERGY	Dummy equal to one if the individual is affected by allergy, zero otherwise	0.12	0.32	0	1	76,810
CELIAC	Dummy equal to one if the individual is celiac, zero otherwise	0.00	0.07	0	1	80,000
HEART_PRO	Dummy equal to one if the individual is affected by heart problem, zero otherwise	0.05	0.22	0	1	79,169
STROKE	Dummy equal to one if the individual had a stroke, zero otherwise	0.02	0.13	0	1	80,091
BULIMIA	Dummy equal to one if the individual is affected by bulimia, zero otherwise	0.00	0.07	0	1	79,588
THYROID	Dummy equal to one if the individual has thyroid problem, zero otherwise	0.06	0.24	0	1	78,789
DEPRESSION	Dummy equal to one if the individual is affected by depression, zero otherwise	0.05	0.22	0	1	76,656
ANXIETY	Dummy equal to one if the individual suffers of anxiety, zero otherwise	0.04	0.19	0	1	78,719

Authors’ elaboration on ISTAT data.

As higher educated people we include those with a Bachelor, Master or Doctorate.We do not consider Italian citizens as those with foreign citizenship. The economic dissatisfaction refers to income: the measure varies from 1 (fully satisfied) to 4 (no satisfied).

Table A2. Correlation matrix.

MIGRAINE	INCOME_DISSAT	AGE	FEMALE	HIGHEDU	MARRIED	SOUTH	ITACIT	INCOME	EMPLOYED	ASTHMA	ALLERGY	CELIAC	HEART_PRO	STOKE	BULIMIA	THYROID	DEPRESSION	ANXIETY
MIGRAINE	1
INCOME_DISSAT	0.0451	1
AGE	−0.0065	−0.053	1
FEMALE	0.1406	−0.0131	0.0011	1
HIGHEDU	−0.0071	−0.1503	−0.1213	0.062	1
MARRIED	0.0095	−0.069	0.194	−0.0801	−0.0419	1
SOUTH	0.0116	0.1221	−0.0289	−0.0737	−0.0002	0.0426	1
ITACIT	0.0253	−0.1248	0.1762	−0.0219	0.0168	0.0527	0.0959	1
INCOME	−0.0189	−0.0962	0.0553	−0.06	0.2259	0.0364	−0.0088	0.0343	1
EMPLOYED	0.0044	−0.1062	−0.5679	−0.0984	0.1686	−0.0504	−0.0346	−0.0886	0.0132	1
ASTHMA	0.068	0.0316	0.0574	0.0048	−0.0179	0.0029	0.0038	0.0118	−0.0117	−0.0511	1
ALLERGY	0.1173	0.01	−0.0631	0.0519	0.03	−0.019	−0.0222	0.0155	−0.0052	0.0356	0.2055	1
CELIAC	0.0221	0.004	−0.0173	0.0351	0.009	−0.0051	−0.0023	0.0118	−0.0009	0.0058	0.0291	0.0403	1
HEART_PRO	0.0375	0.0264	0.2238	−0.0137	−0.033	0.0065	0.0051	0.04	0.0127	−0.1626	0.0714	0.0167	0.0084	1
STOKE	0.015	0.0193	0.1556	−0.016	−0.0347	0.0038	0.001	0.0217	−0.0073	−0.1163	0.0247	−0.0044	0.0099	0.0985	1
BULIMIA	0.0562	0.0228	0.0072	0.0222	0.0031	−0.0074	−0.0061	0.004	0.0035	−0.006	0.0349	0.0287	0.0393	0.0233	0.0123	1
THYROID	0.0888	0.0019	0.0817	0.1842	−0.0094	0.0193	−0.003	0.0289	−0.005	−0.0733	0.0409	0.0539	0.0217	0.0676	0.012	0.0313	1
DEPRESSION	0.1529	0.0855	0.1437	0.067	−0.04	−0.0311	0.002	0.0298	−0.0162	−0.1418	0.0744	0.0413	0.0149	0.1068	0.096	0.1191	0.073	1
ANXIETY	0.142	0.0712	0.1253	0.0671	−0.0352	−0.0251	0.0179	0.0324	−0.0098	−0.1172	0.0703	0.0494	0.0177	0.1003	0.0687	0.1185	0.0713	0.4946	1

For the description of the variables see Table A1.

Table A3. Variance inflation factor (VIF).

Variable	VIF
AGE	1.70
FEMALE	1.07
MARRIED	1.06
SOUTH	1.04
ITACIT	1.06
INCOME	1.02
EMPLOYED	1.56
ASTHMA	1.06
ALLERGY	1.06
CELIAC	1.01
HEART_PRO	1.07
STROKE	1.04
BULIMIA	1.02
THYROID	1.05
DEPRESSION	1.36
ANXIETY	1.35
Mean VIF	1.15

For the description of variables see Table A1.

Table A4. The impact of income dissatisfaction on migraine using age categories.

	1	2	3	4	5	6
INCOME_DISSAT	0.1023***	0.1162***	0.0749***	0.0968***	0.1086***	0.0673***
	0.0237	0.0357	0.0170	0.0245	0.0372	0.0177
Baseline: Young
Adult	0.0401***	0.0417***	0.0424***	0.0281***	0.0300***	0.0299***
	0.0046	0.0047	0.0045	0.0046	0.0047	0.0045
Mature	0.0125*	0.0206**	0.0122*	−0.0002	0.0074	−0.0021
	0.0069	0.0089	0.0064	0.0076	0.0100	0.0068
FEMALE	0.1069***	0.1092***	0.1076***	0.0802***	0.0830***	0.0809***
	0.0028	0.0028	0.0027	0.0030	0.0030	0.0028
MARRIED	0.0163***	0.0173***	0.0138***	0.0211***	0.0219***	0.0189***
	0.0034	0.0040	0.0031	0.0033	0.0038	0.0030
SOUTH	−0.0019	−0.0018	0.0335***	−0.005	−0.005	0.0251***
	0.0045	0.0059	0.0079	0.0047	0.0062	0.0080
ITACIT	0.0826***	0.0826***	0.0736***	0.0658***	0.0659***	0.0566***
	0.0089	0.0105	0.0079	0.0092	0.0110	0.0081
INCOME	0.0000	0.0000*	0.0000	0.0000	0.0000	0.0000
	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000
EMPLOYED	0.0158**	0.0192**	0.0104*	0.0293***	0.0320***	0.0233***
	0.0069	0.0091	0.0058	0.0069	0.0090	0.0058
ASTHMA				0.0066	0.0068	0.0065
				0.0939***	0.0931***	0.0940***
ALLERGY				0.0042	0.0043	0.0042
				0.0340*	0.0340*	0.0354*
CELIAC				0.02	0.02	0.0198
				0.0333***	0.0334***	0.0346***
HEART_PRO				0.0064	0.0066	0.0063
				0.0136	0.0146	0.0161
ICTUS				0.0105	0.0105	0.0104
				0.1278***	0.1268***	0.1346***
BULIMIA				0.0207	0.021	0.0204
				0.0670***	0.0667***	0.0666***
THYROID				0.0056	0.0057	0.0056
				0.1410***	0.1399***	0.1460***
DEPRESSION				0.0082	0.0092	0.0077
				0.1323***	0.1317***	0.1355***
ANXIETY				0.0091	0.0096	0.0088
				0.0091	0.0096	0.0088
Observations	72,520	72,520	72,520	63,489	63,489	63,489
R-2	0.0155	0.0087	0.0268	0.0477	0.0411	0.0616
Fixed Effect	Sector	Job Position	Region	Sector	Job Position	Region

For the description of variables see Table A1. The dependent variable is MIGRAINE. Superscripts ***, ** and * denote statistical significance at the 1, 5 and 10 percent level, respectively. The standard errors (in italics) are robust to heteroskedasticity and autocorrelation. Young refers to people from 15 to 30 years old. Adults refers refers to people from 31 to 60 years old, while the rest refers to mature category.