Authors’ reply

Dear Editor,

We appreciate the comments by Haag, primarily because they respond to the main aim of the review we wrote on MOH: to draw attention and stimulate research on a condition that is severe, disabling, potentially harmful, under-diagnosed and undertreated [1].

Regarding the selection of papers, it was based, as in most of the reviews published in the literature, primarily on objective criteria related to the scientific strength of the paper.

Increased perception and recognition of MOH as a severe health condition, promulgated also by the International Headache Society with the identification of MOH as a separate entity [2], has fostered the diffusion among the medical community of the virtuous process represented by: awareness of a disease → detection/identification of sufferers → management of the disease. This is happening in Europe, America, Asia and hopefully elsewhere, and does not strictly mean that we believe that the number of subjects overusing drugs for acute migraine treatment is increasing, although this remains a possibility, given the increased awareness and improved diagnostics potency of the medical community and the increased availability and advertisement of drugs.

The focus on Latin American countries was prompted by the observation, that no figures on MOH in Latin American countries were available while revising the very scarce data from the literature on MOH. This findings was somewhat surprising and worrying because we knew from the collaboration with our Latin American colleagues and partners within the Comoestas Project¹ that MOH is definitely an issue in their countries, potentially even bigger, because of a lessened attention of the health system to the headache problem and an easier access to OTC drugs and to herbal derivatives containing ergot derivatives. Given these premises, we felt that the addition of a paragraph on the very limited data available on MOH in Latin American countries (even if partly coming from a preliminary, unpublished report) would be useful to draw attention on the issue and to spur further research on the topic.

The paper from Meskunas [3] was amply mentioned because it represents a good example of a well-done scientific evaluation of a problem and of its persistence, notwithstanding the dramatic changes in terms of symptomatic drugs endured by headache community in the last 15 years. Haag is right when he suggests, in agreement with ICHD-II, that MOH results from the interaction of a drug used in excess and a susceptible terrain, while little doubt exists as regards the causal role of symptomatic drugs in the development of true MOH, but discussion of the etiology and/or pathophysiology of MOH was beyond the scopes of the review.

As regards the ergotamine preparation, it is still available on the German market but it is no longer used as suggested by a large population-based study on 16,500 subjects (Katsarava et al., unpublished data).

Finally, a very limited number of papers have investigated and described MOH in children and adolescents. To the best of our knowledge, the 25 young subjects with daily or almost daily headache and overusing analgesics described by Hering-Hanit and Gadot [4] indeed represent the largest series of MOH in children and adolescents as confirmed by their improvement following analgesic withdrawal.

We are thankful to Haag for his criticism, because criticism is one of the bases for improving scientific knowledge. In this frame, we have to respect Haag’s personal judgment but do not accept it because the review was prepared scrupulously by scientists and headache experts who did their best to put together the most reliable knowledge on MOH published in the international literature. Furthermore, the review was peer-reviewed and published in a well-known and highly respected headache journal.

Appendix

Members of The Comoestas Consortium are as follows: C. Tassorelli (Project Manager), G. Sances, G. Sandrini, F. Blandini, P. Rossi, N. Arce-Leal (IRCCS “Neurological Institute C. Mondino” Foundation, University Centre for Headache and Adaptive Disorders, Pavia), R. Jensen (Region Hovedstaden, Glostrup Amtssygehuset), M. Lainez (Fundación de la Comunidad Valenciana para la Investigación Biomédica, la Docencia y la Cooperación Internacional y para el Desarrollo del Hospital Clínico Universitario de Valencia - Spain), D. Mueller (Universitaetsklinikum Essen), J. Leston, M.T. Goicochea (Fundacion para la Lucha contra las Enfermedades Neurologicas de la Infanzia, Buenos Aires - Argentina), R. Fadic, B. Shand (Pontificia Universidad Catolica de Chile, Santiago - Chile).