Comments on Allena et al.: From drug-induced headache to medication overuse headache. A short epidemiological review, with a focus on Latin American countries
© Springer-Verlag 2009
Received: 16 August 2009
Accepted: 26 August 2009
Published: 27 October 2009
The selection criteria of the literature included in this review remain unclear. What were the criteria for “scientific validity”, “historical value”, “importance”, and “relevance”?
What supports the authors’ statement that “prevalence (of MOH) is increasing worldwide”? The quoted review by Diener and Limmroth  includes the statement “there is increasing evidence that the overuse of analgesics and subsequent MOH is not only prevalent in Europe and North America but is a growing problem in Asian countries—in China and Taiwan the prevalence is the same as in Europe”. The fact that data on MOH prevalence are reported from a growing number of countries cannot justify the claim of an “increasing prevalence”. The second review quoted by the authors—by Limmroth & Katsarava —does not provide any corresponding evidence.
The “discussion of the relevant epidemiological data available on MOH, focusing on the information regarding this condition in Latin American (LA) countries” announced by the authors plainly should have been omitted, since there seem to be hardly any data at all.
Results from clinical case series (from specialized headache clinics) cannot be generalized due to the immanent selection bias, not even the extent of which can be assessed.
The authors quote the study by Meskunas et al.  which showed that in one US headache clinic the relative frequency (correctly not called prevalence by Meskunas et al.) of (probable) MOH remained stable (with a tendency to decrease) over 15 years when the number of tablets/day is considered, but the medications used have changed substantially. Moreover, they highlight MOH development with overuse of various triptans. Reports of occurrence of MOH exist for practically all analgesics and migraine medications—independent of their composition. Independent of whether MOH frequency could also correlate with the frequency of use of the active substance among the population, one explanation would be that MOH development is primarily related not so much to the use of certain substances in migraine and headache medications, but more to the frequency and dosage in a vulnerable subpopulation of patients with migraine and tension-type headache. This very obvious explanation has not even been considered by the authors.
Epidemiological studies do not unambiguously show whether frequent medication intake is the cause or consequence of chronic headache. Authors of various publications point this out explicitly. Unfortunately, this important information is missing in the review by Allena and co-authors.
The statement that ergotamine has been taken off the market in Germany is not correct. Tablets containing 2 mg ergotamine (Ergo-Kranit®) are still available in Germany.
The reference of a study by Hering-Hanit and Gadoth  on the topic of MOH in children and adolescents in connection with their intake of caffeine is misleading, just as the statement that this indicates some early overuse. In their study, Hering-Hanit and Gadoth investigated the excessive caffeine consumption in the form of cola drinks, which can hardly be considered medications. Therefore, this paper cannot make a contribution to the evaluation of headache with medication overuse.
Consequently, this review does not meet the demands set by the authors themselves—neither in its methods nor in its contents.
- Allena M, Katsarava Z, Nappi G, COMOESTAS Consortium (2009) From drug-induced headache to medication overuse headache. A short epidemiological review, with a focus on Latin American countries. J Headache Pain 10:71–76. doi:10.1007/s10194-009-0101-y, 19238511PubMed CentralPubMedView ArticleGoogle Scholar
- Diener H-C, Limmroth V (2004) Medication-overuse headache: a worldwide problem. Lancet Neurol 3:475–483, 10.1016/S1474-4422(04)00824-5, 15261608PubMedView ArticleGoogle Scholar
- Limmroth V, Katsarava Z (2004) Medication overuse headache. Curr Opin Neurol 17:301–306, 10.1097/00019052-200406000-00011, 15167065PubMedView ArticleGoogle Scholar
- Meskunas CA, Tepper SJ, Rapoport AM, Sheftell FD, Bigal ME (2006) Medications associated with probable medication overuse headache reported in a tertiary care headache center over a 15-year period. Headache 46:766–772, 10.1111/j.1526-4610.2006.00442.x, 16643579PubMedView ArticleGoogle Scholar
- Hering-Hanit R, Gadoth N (2003) Caffeine-induced headache in children and adolescents. Cephalalgia 23:332, 10.1046/j.1468-2982.2003.00576.x, 1:STN:280:DC%2BD3s3ls1emtg%3D%3D, 12780761PubMedView ArticleGoogle Scholar