The Epidemiology of Obesity and Headache
Headache, in general, is incredibly common. The global lifetime prevalence of headache (all types), is 66% (male 65%, female 69%); while the 1-year period prevalence is approximately 47% (male 37%, female 52%).
Of the primary headache disorders, TTH is the most common, with a lifetime prevalence of approximately 46% globally and a 1-year period prevalence of 38%. The 1-year incidence for TTH is between 14 and 44 per 1000 person-years. There is a female predilection for TTH, with a female to male ratio between 1.2:1 and 3:1.
Migraine, while less common than TTH in the general population, is the most common primary headache disorder presenting to a physician's office. The lifetime prevalence of migraine is approximately 14% globally, with a 1-year period prevalence of 12–15%. Migraine incidence has been estimated between 3 and 18 cases per 1000 person-years. As with TTH, migraine is more common in women (17.6%) than men (6.5%). Additionally, in both sexes, migraine is most prevalent in those of reproductive age (between 20 and 50 years of age).
While it has been recognized that obesity incidence and prevalence rates have increased in the past several decades (particularly between 1999 and 2008), it is controversial as to if migraine incidence and prevalence rates have likewise increased in past decades. Several studies have reported that the incidence and/or prevalence of migraine in adolescents and adults have increased, particularly between the late 1980s to late 1990s and the mid-to-late 1990s to the early 2000s (Table 1). One study evaluating changes in migraine prevalence over time reported no increase in migraine prevalence between 1989 and 2001. However, study methodologies in the earlier studies, at least in part, limit our ability to draw firm conclusions. For example, some of these studies measured medically ascertained migraine (eg, clinician-diagnosed) and therefore are also likely measuring secular changes in medical consultation for migraine. Additionally, other studies used self-reported or non-International Classification of Headache Disorders (ICHD) migraine diagnoses (Table 1). Further, others have discussed an apparent increase or a lack of change in migraine prevalence over time without formal statistical evaluations being conducted. Regardless of whether the incidence and/or prevalence of migraine have increased, the existence or absence of such changes may be irrelevant to the validity of the migraine-obesity association, as such comparisons likely represent an example of an ecological fallacy (see also http://www.stanford.edu/class/ed260/freedman549.pdf for further description and examples of ecological fallacies).
Epidemiology of Primary Headache
Headache, in general, is incredibly common. The global lifetime prevalence of headache (all types), is 66% (male 65%, female 69%); while the 1-year period prevalence is approximately 47% (male 37%, female 52%).
Of the primary headache disorders, TTH is the most common, with a lifetime prevalence of approximately 46% globally and a 1-year period prevalence of 38%. The 1-year incidence for TTH is between 14 and 44 per 1000 person-years. There is a female predilection for TTH, with a female to male ratio between 1.2:1 and 3:1.
Migraine, while less common than TTH in the general population, is the most common primary headache disorder presenting to a physician's office. The lifetime prevalence of migraine is approximately 14% globally, with a 1-year period prevalence of 12–15%. Migraine incidence has been estimated between 3 and 18 cases per 1000 person-years. As with TTH, migraine is more common in women (17.6%) than men (6.5%). Additionally, in both sexes, migraine is most prevalent in those of reproductive age (between 20 and 50 years of age).
Migraine Incidence and Prevalence Rates Across Time
While it has been recognized that obesity incidence and prevalence rates have increased in the past several decades (particularly between 1999 and 2008), it is controversial as to if migraine incidence and prevalence rates have likewise increased in past decades. Several studies have reported that the incidence and/or prevalence of migraine in adolescents and adults have increased, particularly between the late 1980s to late 1990s and the mid-to-late 1990s to the early 2000s (Table 1). One study evaluating changes in migraine prevalence over time reported no increase in migraine prevalence between 1989 and 2001. However, study methodologies in the earlier studies, at least in part, limit our ability to draw firm conclusions. For example, some of these studies measured medically ascertained migraine (eg, clinician-diagnosed) and therefore are also likely measuring secular changes in medical consultation for migraine. Additionally, other studies used self-reported or non-International Classification of Headache Disorders (ICHD) migraine diagnoses (Table 1). Further, others have discussed an apparent increase or a lack of change in migraine prevalence over time without formal statistical evaluations being conducted. Regardless of whether the incidence and/or prevalence of migraine have increased, the existence or absence of such changes may be irrelevant to the validity of the migraine-obesity association, as such comparisons likely represent an example of an ecological fallacy (see also http://www.stanford.edu/class/ed260/freedman549.pdf for further description and examples of ecological fallacies).