Page 62 - Migraine, the heart and the brain

Chapter 3
Migraine and ongoing recurrence of migraine attacks.
Participants were asked during a telephone interview whether they ever had had migraine attacks and, if so, what the average attack frequency had been prior to CAMERA-1 and since then. One participant who was classi ed as control at CAMERA-1 had become migraineur without aura during the follow-up period. Participants who ful lled the criteria of migraine at CAMERA-1 but had stopped experiencing migraine attacks during last year of follow-up were considered currently inactive lifetime migraineurs22 The interview was structured by using personal benchmarks (e.g., pregnancy) for when a different migraine pattern had started or stopped.3 These benchmarks were used to de ne periods and to compute the average migraine attack frequency (expressed as mean number of attacks per month).Information was collected on migraine prophylaxis and treatment. Active recurrence of migraine attacks was de ned as having had at least one migraine attack in the 12 months22 prior to the CAMERA-2 MRI investigation.
Study population.
Of the 435 original participants of CAMERA-1, 286 (66%) underwent a follow-up MRI scan (migraine with aura: n = 114; migraine without aura: n = 89; nonmigraine controls: n = 83).3 Mean follow-up was 8.5 years (range 7.9–9.2; SD 0.24 years).3 Of these, 272/286 (95%) agreed to undergo TCD-c. Usable TCD-c data could be obtained from 235/272 (86%) participants: in 23/272 (8%), no adequate bone window was found, 9/272 (3%) had no adequate cubital venous access, and in 5/272 (2%) offline analysis was not possible due to technical failures. The 37 participants for whom no usable TCDc was available were otherwise comparable to the participants with usable TCD-c data with respect to age, sex, cardiovascular history, and migraine status.
As explained before,3 there were no obvious reasons to assume that there was a serious selection bias from CAMERA-1 to CAMERA-2, which could have materially affected the results.3
Reasons for nonparticipation were no interest (n = 51), inability to visit research center (n = 30), claustrophobia (n = 8), and non-neurologic illness (n = 6).3 There was no association between participation rate and diagnosis of migraine. Compared to nonparticipants, participants were slightly younger, more frequently reported high educational level, and smoked fewer packyears.3
60