Results

Headache
Headache in general has been reported in 49 studies (Table 1), whereof 34 have concerned headache during the last year or less (here summarized as “current headache”, also including studies where timeframe were not stated). Calculating the mean of all the studies comprising more than 205,000 adult participants, current headache occurred in 53% of adults (61% among women and 45% among men). The prevalence in the 12 studies restricted to children and youth, including >37,000 participants, was the same (53%), but the only two studies on the elderly, from Italy, showed a somewhat lower figure (36%). The total lifetime prevalence of headache among adults was as expected higher than that of current headache (77%).
Table 1 Studies on headache prevalence
Country (year) Reference Time frame Method N Age range (years) Headache Chronic headache
M F Total M F Total
Adults or all ages
 Austria (2003) Lampl [37] 1-y P.i. 997 ≥15 43.6 54.6 49.4
 Croatia (2001, 2003) Zivadinov [38, 49] L.t. P.i. 3,794 15–65 65.2
 Denmark (1991) Rasmussen [10] 1-y P.i. 740 25–64 3
 Denmark (1991) Rasmussen [10] L.t. P.i. 740 25–64 93 99 96
 Finland (1981) Nikiforow [45] 1-y P.i. 200 >15 69 83 77
 Finland (1981) Nikiforow [45] L.t. P.i. 200 >15 91
 France (1992) Henry [51] L.t. Q 4,204 5–65 35
 France (2002) Henry [20] N.s. Q 10,585 ≥15 29.2 3.0
 France (2003) Lanteri-Minet [17] L.t. Q 10,585 ≥15 1.6 4.2 3
 France (1996) Michel [46] 3-m Q 9,411 >18 39.0 58.0 49
 Germany (1994) Gobel [52] L.t. Q 4,061 ≥18 71.4
 Germany (2009) Pfaffenrath [61] 6-m P.i. 7,417 ≥20 49.5
 Germany (2009) Radke [62] 1-y T.i. 7,341 ≥18 53.0 66.6 60.2
 Georgia (2009) Katsarava [12] 1-y P.i. 1,145 ≥16 46.3 7.6
 Greece (1996) Mitsikostas [18] 1-y Q 3,501 15–75 19.0 40.0 29 2.1 6.8 4.5
 Italy (1988) D’Alessandro [47] 1-y Q 1,154 >7 35.3 46.2 46
 Netherlands (2006) Wiendels [13] 3-m Q 16,232 25–55 3.7
 Norway (2000) Hagen [15] 1-y Q 51,383 ≥20 29.6 45.7 37.7 1.7 2.8 2.4
 Norway (2008) Grande [22] 1-y Q 20,598 30–44 2.9
 Norway (2008) Russell [43] 1-y Q 21,800 20–80 69.6 84.0 77.2
 Portugal (1995) Pereira Monteiro [53] L.t. Q 2,008 All ages 88.6 4.1
 Spain (1999) Castillo [14] 1-y Q 2,253 >14 1.0 8.7 4.7
 Spain (1994) Laínez [50] L.t. P.i. 2,231 16–65 86.7
 Sweden (2001) Dahlof [42] 1-y Q 1,668 18–74 50 76 63
 Sweden (2006) Molarius [63] 3-m Q 43,770 18–79 10.4 22.9 16.7
 Turkey (2005) Boru [64] L.t P.i. 1,835 15–45 70.9
 UK (1975) Waters [65] 1-y Q 1,718 >21 63.5 78.4 71.0
 UK (2005) Boardman [48] 1-y Q 1,589 18–90 76
 UK (1977) Crisp [66] L.t. Q 727 >7 35.3 46.2
 UK (2003) Boardman [67] L.t. Q 1,662 ≥18 90.2 94.4 92.6
 UK (2003) Boardman [67] 3-m Q 1,662 ≥18 62.0 76.8 70.3
Children and youth
 Finland (1983) Sillanpää [68] 1-y Q 3,784 13 79.8 84.2 82.0
 Finland (1994) Metsähonkala [69] 1-y Q 3,580 8–9 36.5
 Finland (1991) Sillanpaa [70] 1-y Q 4,405 5 19.5
 Finland (1994) Metsähonkala [69] L.t. Q 3,580 8–9 36.5
 Germany (2004) Roth-Isigkeit [71] 3-m Q 735 10–18 58.9 73.1 66
 Italy (1995) Raieli [72] 1-y P.i. 1,445 11–14 19.9 28.1 23.9
 Norway (2004) Zwart [19] 1-y Q 8,255 13–19 69.4 84.2 76.8 0.2 0.8 0.5
 Serbia (2007) Milanovic [73] L.t. P.i. 1,259 7–12 32.8
 Sweden (2004) Laurell [33] 1-y Q 1,850 7–15 39.3 50.3 44.8
 Sweden (1962) Bille [74] L.t. Q 8,993 7–15 58 59.3 58.7
 Turkey (2005) Bugdayci [75] N.s. P.i. 5,777 8–16 46.2 52.8 49.2 1.5
 Turkey (2007) Akyol L.t. Q 7,721 9–17 79.6 87.1 83.4
 Turkey (2006) Karli [76] 1-y Q 2,387 12–17 45.1 59.8 52.2
 Turkey (2006) Unalp [77] N.s. Q 2,384 14–18 36 53 46
 UK (1977) Deubner [78] 1-y Q 600 10–20 74.4 81.5 78.0
 UK (1994) Abu-Arefeh [79] 1-y Q 2,165 5–15 66
Elderly
 Italy (2001) Prencipe [16] 1-y P.i. 833 ≥65 36.6 62.1 51 2.5 6 4.4
 Italy (2003) Camarda [80] 1-y P.i. 1,031 ≥65 16.5 26.3 21.8
1-y 1-year prevalence, 3-m 3-month prevalence, 6-m 6-month prevalence, L.t. lifetime prevalence, N.s. prevalence not stated, P.i. personal interview, T.i. telephone interview, Q questionnaire, M males, F females

Migraine
The studies on migraine are presented in Table 2. The mean prevalence of current migraine among >170,000 adults was 14.7% (8% in men and 17.6% in women). In studies restricted to children and youth (>36,000 participants), the prevalences were lower (9.2% for all, 5.2% in boys and 9.1% in girls). Lifetime prevalences were higher (16, 11 and 20%, respectively).
Table 2 Studies on migraine prevalence
Country (year) Reference Time frame Method N Age range (years) Migraine
M F Total
Adults or all ages
 Austria (2003) Lampl [37] 1-y P.i. 997 ≥15 6.1 13.8 10.2
 Croatia (2001) Zivadinov [38] 1-y P.i. 3,794 15–65 13 20.2 16.7
 Croatia (2001, 2003) Zivadinov [38, 49] L.t. P.i. 3,794 15–65 14.8 22.9 19
 Denmark (1991) Rasmussen [10] 1-y P.i. 740 25–64 6 15 10
 Denmark (1991) Rasmussen [10] L.t. P.i. 740 25–64 8 25 16.1
 Denmark (1995) Russell [81] L.t. Q 4,061 40 12 24 18
 Denmark (2005) Lyngberg [36] 1-y P.i. 207 25–36 5.4 23.5 15.5
 Denmark (2006) Russell [44] 1-y Q 28,195 12–41 13.9 24.3 19.1
 France (1992) Henry [51] L.t. Q 4,204 5–65 6.1 17.6 12.1
 France (2002) Henry [20] N.s. Q 10,585 ≥15 10 23 17
 France (2005) Lantéri-Minet [9] N.s. Q 10,532 ≥18 6.3 15.7 11.2
 France (1996) Michel [46] 3-m Q 9,411 >18 8 18 15
 Germany (1994) Gobel [52] L.t. Q 4,061 ≥18 22 32 27.5
 Germany (2009) Pfaffenrath [61] 6-m P.i. 7,417 ≥20 11.4
 Germany (2009) Radke [62] 1-y T.i. 7,341 ≥18 5.3 15.6 10.6
 Georgia (2009) Katsarava [12] 1-y P.i. 1,145 ≥16 15.6
 Hungary (2000) Bank [40] 1-y Q 813 15–80 2.7 6.9 9.6
 Netherlands (1999) Launer [41] 1-y Q 6,491 20–65 7.5 25 16.3
 Netherlands (1999) Launer [41] L.t. Q 6,491 20–65 13.3 33 23.2
 Norway (2000) Hagen [15] 1-y Q 51,383 ≥20 7.5 15.6 11.6
 Norway (2006) Sjaastad [82] N.s. P.i. 1,838 18–65 17.5 28.4 23.0
 Norway (2008) Russell [43] L.t. Q 21,800 20–80 18.1 34.1
 Portugal (1995) Pereira Monteiro [53] L.t. Q 2,008 All 8.8
 Spain (1994) Laínez [50] L.t. P.i. 2,231 16–65 8 17 12
 Sweden (2000) Mattsson [83] L.t. Q 722 40–74 31
 Sweden (2000) Mattsson [83] 1-y Q 728 40–74 18
 Sweden (2001) Dahlöf [42] 1-y Q 1,668 18–74 9.5 16.7 13.2
 Sweden (2006) Molarius [63] 3-m Q 43,770 18–79 2.4 5.5 4.0
 Switzerland (1994) Merikangas [39] 1-y P.i. 379 29–30 24.6
 Turkey (2005) Boru [64] L.t. P.i. 1,835 15–45 15.8
 Turkey (2005) Celik [55] L.t. P.i. 386 >14 9.3 29.3 19.9
 Turkey (2002) Kececi [56] L.t. P.i. 947 ≥7 7.9 17.1 12.5
 UK (2003) Steiner [57] 1-y T.i. 4,007 16–65 7.6 18.3 14.3
Children and youth
 Finland (1994) Metsähonkala [69] L.t. Q 3,580 8–9 3 2.3 2.7
 Germany (2007) Fendrich [84] 3-m Q 3,324 12–15 4.4 9.3 6.9
 Germany (2009) Heinrich [85] 6-m Q 2,553 9–14 13.1
 Greece (1999) Mavromichalis [86] 1-y Q 3,509 4–15 5.2 7.3 6.2
 Italy (1995) Raieli [72] 1-y P.i. 1,445 11–14 2.7 3.3 3.0
 Norway (2004) Zwart [19] 1-y Q 8,255 13–19 4.8 9.1 7.0
 Serbia (2007) Milanovic [73] L.t. P.i. 1,259 7–12 2.1 4.6 3.3
 Sweden (2004) Laurell [33] 1-y Q 1,850 7–15 9.8 12.2 11.0
 Turkey (2005) Bugdayci [75] N.s. P.i. 5,777 8–16 10.4
 Turkey (2004) Zencir [87] N.s. Q 2,490 11–18 6.7 11.0 8.8
 Turkey (2006) Karli [76] 1-y Q 2,387 12–17 14.5
 Turkey (2007) Akyol [88] L.t. Q 7,721 9–17 7.8 11.7 9.7
 Turkey (2006) Unalp [77] 1-y Q 2,384 14–18 9.6
 UK (1994) Abu-Arefeh [79] 1-y Q 2,165 5–15 9.7 11.5 10.6
Elderly
 Italy (2001) Prencipe [16] 1-y P.i. 833 ≥65 7.4 13.8 11
 Italy (2003) Camarda [80] 1-y P.i. 1,031 ≥65 2.3 6.4 4.6
For abbreviations see Table 1
Most studies only report the prevalence of “strict migraine”, i.e. cases that comply with all the criteria of either migraine without (ICHD-2 1.1) or with aura (ICHD-2 1.2). However, if also probable migraine (ICHD-2 1.6), i.e. cases which fulfil all but one of the criteria, is included, the proportion with migraine is almost doubled [9].

TTH
Nineteen studies have reported the TTH prevalences (Table 3). Overall, the prevalence of current TTH among >66,000 adults was 62.6%, and chronic TTH (i.e. on ≥15 days per month) occurred in 3.3%. Much lower figures (current TTH 15.9%, chronic TTH 0.9%) were found in the nine studies among almost 25,000 children and youth.
Table 3 Studies on the prevalence of tension-type headache
Country (year) Reference Time frame Method N Age range (years) TTH Chronic TTH
M F Total M F Total
Adults
 Croatia (2001, 2003) Zivadinov [49] L.t. P.i. 3,794 15–65 32.3 37.1 34.8
 Denmark (1991) Rasmussen [10] 1-y P.i. 740 25–64 63 86 74
 Denmark (1991) Rasmussen [10] L.t. P.i. 740 25–64 69 88 78 3.0
 Denmark (2005) Lyngberg [36] 1-y P.i. 207 25–36 81.5 90.4 86.5 4.8
 Denmark (2006) Russell [44] 1-y Q 28,195 12–41 78.9 92.5 86.0 0.5 1.3 0.9
 Georgia (2009) Katsarava [12] 1-y P.i. 1,145 ≥16 37.3 3.8
 Germany (1994) Gobel [52] L.t. Q 4,061 ≥18 37 39 38 3.0 3.0 3.0
 Germany (2009) Pfaffenrath [61] 6-m P.i. 7,417 ≥20 31.5 1.25
 Germany (2009) Radke [62] 1-y T.i. 7,341 ≥18 53.0 66.6 60.2
 Norway (2008) Grande [22] 1-y Q 20,598 30–44 1.6 3.7 2.8
 Portugal (2005) Pereira Monteiro [53] L.t. Q 2,008 All ages 48.7 4.1
 Turkey (2003) Koseoglu [89] 1-y P.i. 1,146 45–64 18.8 6.3
Children/youth
 Finland (2002) Anttila [90] N.s. Q 1,135 12 12.2 0
 Germany (2007) Fendrich [84] 3-m Q 3,324 12–15 19.1 21.2 20.2 0.2
 Norway (2004) Zwart [19] 1-y Q 8,255 13–19 12.5 23.2 18.0
 Serbia (2007) Milanovic [73] L.t. P.i. 1,259 7–12 0.9 1.7 1.3
 Sweden (2004) Laurell [33] 1-y Q 1,850 7–15 7.9 11.8 9.8
 Turkey (2005) Bugdayci [75] N.s. P.i. 5,777 8–16 24.7 1.5
 Turkey (2004) Kaynak Key [91] N.s. Q 2,226 17–21 14.3 22.7 20.35 0.8 2.8 1.9
 Turkey (2006) Unalp [77] 1-y Q 2,384 14–18 5.7
For abbreviations see Table 1

Chronic headache and MOH
The definitions of chronic headache varied considerably among studies. Only two studies used the same criteria for chronicity as with chronic TTH (>180 days/year [10] or >14 days/month for more than 3 months during the last year [11]). Most other studies used a definition of ≥15 days per month [12–16] or simply daily headache [17–19].
The 1-year prevalence of current chronic daily headache was 4.0% (mean of 8 studies) [10, 12, 14, 15, 18, 20–22]. A similar figure (4.4%) was found in one study restricted to the elderly [16], but in studies on children and youth, the figure was lower (0.5% among 13–19-year-old in Norway), and 1.5% among 8–16-year-old in Turkey. The highest figure (7.6%) was found among adults in Georgia [12]. Medication overuse is frequent among those with chronic headache, and possible medication overuse headache (i.e. headache ≥15 days per month and use of medication ≥3 months) was found to affect 0.9% in Georgia [12] and 1% of adults in Spain [14, 23]. In the HUNT studies in Norway from the 1990s the prevalence was 1% in adults [24] and 0.5% in adolescents [25], whereas a more recent study showed 1.7% [26]. In Germany, a recent study demonstrated a prevalence of 2% [27].

Cluster headache
In comparison to migraine and TTH, cluster headache is rare, and to make the diagnosis from questionnaires alone has never been validated. Therefore, the prevalence should preferably be made by personal interview and examination by a neurologist in a large population. A lifetime prevalence of 0.326% was found in a study in which the diagnosis was made by face-to-face interview by a headache expert among more than 1,800 inhabitants of a Norwegian rural community [28]. This is similar to the figure (0.279%) found in an Italian town among >10,000 patients registered in the lists of general practitioners, the sample being representative of the general population [29]. Questionnaires or telephone interviews were used to screen the population, and suspected cases were interviewed by a headache specialist to confirm the diagnosis. These high prevalences are also supported by recent data from a Swedish twin registry study giving a lifetime prevalence of around 0.2% [30]. In Germany, suspected cluster headache cases detected by a questionnaire and interviewed by a neurologist in a population-based study revealed a prevalence of 0.12% [31]. In Georgia, one case was found in door-to-door survey among 1,145 individuals, which corresponds to 0.09% [32].

Increase in headache
By studying headache prevalence with an interval of some years in the same community and using the same method, it may be possible to study time-trends in headache prevalence. A study from Sweden indicates a marked increase of both headache and migraine in schoolchildren over a period of 40 years [33], and in a Finnish community there was a significant increase among 8-year-old children in headache (and abdominal pain) over a 10-year period [34]. In another Finnish study, three population-based studies on migraine and other headaches among 7-year-old children conducted in 1974, 1992 and 2002 with almost identical study design indicated increased incidence rates both of headaches in general (incidence in the 3 years: 58, 156, 278/1,000 person-years) and migraine (20, 59 and 133) [35]. Among young adults (25–36 years) in Denmark, there was over a 12-year period a significant increase in TTH, particularly the frequent type. There was also a significant increase in the proportion with relatively frequent migraine, but the increase for migraine in general was not significant [36].

Methodological analyses
To explore to which degree the method of data collection in epidemiologic studies is important for the results, we compared the mean prevalence of studies in adults using either personal interview or questionnaire. For 1-year prevalences (both sexes) of migraine, the mean of the five studies using personal interview [10, 36–39] was 15.3%, compared to 14.0% in the five studies using questionnaires [15, 40–44]. For headache in general, the total prevalence seemed to be higher in the three studies using personal interview [12, 37, 45] than in the eight studies using questionnaires [15, 18, 20, 42, 43, 46–48] (57.6 vs. 40.6%). For lifetime prevalences of headache in general, the mean prevalence was somewhat higher in the four studies using personal interview [10, 45, 49, 50] than in the four using questionnaires [51–54] (84.7 vs. 71.9%). However, for lifetime prevalences of migraine, the mean of the five studies using personal interview [10, 38, 50, 55, 56] was somewhat lower than in the four studies using questionnaires [41, 51–53] (15.9 vs. 17.9%).
As to the effect of using different timeframes in the studies, there was little difference between the migraine prevalence in those studies in which the timeframe was not stated [9, 51] compared to the studies asking about headache during the last year [10, 15, 36, 37, 40–42, 49, 57] (12.9 vs. 13.0%).