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

OBJECTIVE: We investigate whether and to what extent income dissatisfaction (ID) is an important determinant of migraine. Indeed, ID may play a more relevant role in migraines than realized income, and it may affect both low and high-income people. DESIGN: We exploit the Italian Statistical Institute (ISTAT) survey covering about 80,000 individuals for this study. On the methodological ground, an instrumental variable probit model has been implemented. MAIN OUTCOME MEASURES: To measure income dissatisfaction we exploit a self-reported status ranging from 1 to 4, while the migraine variable captures whether the individual suffers from migraine. RESULTS: The results show that the higher the ID the greater the probability of having a migraine. This relationship is robust to the level of realized income, socioeconomic characteristics of the individual, and the existence of other illnesses. CONCLUSIONS: The high relevance of ID among low-income as well as high-income people opens up a new perspective on the determinants of migraines and provides an explanation of the contrasting evidence in the literature about the income-migraine nexus.