Neurology -- Correspondence for Rose et al., 68 (20) 1694-1700

Correspondence published:

Migraine and retinal microvascular abnormalities: The Atherosclerosis Risk in Communities Study: Piotr Kruszewski, Leszek Bieniaszewski (9 September 2007)

Reply from the authors: Kathryn M. Rose (9 September 2007)

Migraine and retinal microvascular abnormalities: The Atherosclerosis Risk in Communities Study 9 September 2007

Piotr Kruszewski,
Medical University of Gdansk, Dept. of Clinical Physiology
Debinki 7, 80-211 Gdansk, Poland,
Leszek Bieniaszewski
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Re: Migraine and retinal microvascular abnormalities: The Atherosclerosis Risk in Communities Study

pkruszew{at}amg.gda.pl Piotr Kruszewski, et al.

Rose et al concluded that “persons with migraine and other headaches were more likely to have retinopathy signs.” [1] They divided the study population into four groups: “migraine/other headache with aura”; “migraine without aura”; “other headache without aura”; and “no headache.” The names of the last two groups may be misleading because they pertain only to headaches lasting more than 4 hours. This was not mentioned in the Discussion or Conclusion.
Furthermore, the authors used the heading “no headache” group yet several subjects assigned to this group had different headaches --lasting < 4 hours-- as a control for the three remaining headache groups. There are several headache types that may last < 4 hours and tension-type headache (TTH) is the most common. According to International Headache Society (IHS) criteria [2], episodic TTH duration is from 30 min to 7 days. A substantial number of TTH sufferers were included in both “other headache without aura” group and “no headache” group.
We have collected information on headache characteristics from 704 face-to-face interviews with normo-tensive subjects as well as patients with hypertension (mean age 44 years, 72% males, 48% hypertensives, 10% diabetics, 22% current smokers). [3] A history of headache (which included 12 months preceding the interview) was reported by 542 (77%) subjects. The IHS criteria for migraine and TTH were fulfilled by 70 (10%) and 385 (55%) participants, respectively. Out of 206 subjects with non-migraine headaches lasting > 4 h, 168 (82%) persons fulfilled criteria for TTH. In the remaining group of 428 participants who did not report headaches lasting > 4h, only 162 (38%) subjects reported no headache within last 12 months, while 217 (51%) persons fulfilled criteria for TTH.
The majority of our subjects in groups corresponding to “other headache without aura” group and “no headache” group were TTH sufferers. Since the frequency of TTH in Rose at al’s study is not known, their conclusions concerning non-migraine headaches should be taken with caution.
The results would be more convincing if the group of subjects with no headache at all was extracted from the study population as a control. If this is not feasible, “other headache without aura” and “no headache” groups should be pooled together to serve as a reference for migraine patients. The latter approach would be more concordant with the title of the article. [1]
References
1.Rose KM, Wong TY, Carson AP, Couper DJ, Klein R, Sharrett AR. Migraine and retinal microvascular abnormalities. The Atherosclerosis Risk in Communities Study. Neurology 2007;68:1694-1700.
2.The International Classification of Headache Disorders. 2nd Edition. Cephalalgia 2004;24(Suppl.1).
3.Kruszewski P, Bieniaszewski L, Neubauer J, Krupa-Wojciechowska B. Headache in patients with mild to moderate hypertension is generally not associated with simultaneous blood pressure elevation. J Hypertens 2000;18:437-444.
Disclosure: The authors report no conflicts of interest.

Reply from the authors 9 September 2007

Kathryn M. Rose,
University of North Carolina at Chapel Hill
137 E. Franklin St., Suite 306, Chapel Hill, NC 27514
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Re: Reply from the authors

Kathryn_Rose{at}unc.edu Kathryn M. Rose

We thank Drs. Kruszewski and Bieniaszewski for their comments on our article. The label “no headache” taken out of context is misleading. However, we appropriately provided a definition for this group in the methods section (i.e., no history of headaches lasting 4+ hours). [1]
In this report and in earlier work [4-6], our primary focus has been on migraine headaches. In earlier work, we found stronger associations of migraine with CVD-related outcomes when aura symptoms were present. [4,6] We also found that when aura symptoms were present, even if all migraine criteria were not met, associations were similar in magnitude to those seen with migraine with aura.
In the current study we combined the two aura groups due to a limited sample size. The "other headaches without aura" group consisted of persons that meet one or more but not all of the necessary criteria for migraine classification. Most met two or more criteria. Thus, we do not agree that it would be appropriate to combine this group with the “no headache” group, where migraine criteria are not met.
The series of questions used in the ARIC Study does not allow us to separate out tension headaches or to identify a subset of persons with a history of no headaches. A large portion of migraine studies in the literature do not stratify by aura status and most use all nonmigraineurs as the referent. Thus, our approach, while not perfect, allows for greater discrimination.
References
4. Stang PE, Carson AP, Rose KM, et al. Headache, cerebrovascular symptoms, and stroke: the Atherosclerosis Risk in Communities Study. Neurology 2005;64:1573-1577.
5. Carson ALP, Rose KM, Sanford CP, et al. Lifetime prevalence of migraine and other headaches lasting four or more hours: the Atherosclerosis Risk in Communities (ARIC) Study. Headache 2004;44:20-28.
6. Rose KM, Carson AP, Sanford CP, et al. Migraine and other headaches: associations with Rose angina and coronary heart disease. Neurology 2004;63:2233-2239.
Disclosure: The authors report no conflicts of interest.