Carryover negligibility and relevance in bioequivalence studies.

The carryover effect is a recurring issue in the pharmaceutical field. It may strongly influence the final outcome of an average bioequivalence study. Testing a null hypothesis of zero carryover is useless: not rejecting it does not guarantee the non-existence of carryover, and rejecting it is not informative of the true degree of carryover and its influence on the validity of the final outcome of the bioequivalence study. We propose a more consistent approach: even if some carryover is present, is it enough to seriously distort the study conclusions or is it negligible? This is the central aim of this paper, which focuses on average bioequivalence studies based on 2 × 2 crossover designs and on the main problem associated with carryover: type I error inflation. We propose an equivalence testing approach to these questions and suggest reasonable negligibility or relevance limits for carryover. Finally, we illustrate this approach on some real datasets.

[Deep venous thrombosis: an early manifestation of Behçet's disease in childhood]. / Trombosis venosa profunda como manifestación precoz de la enfermedad de Behçet en la infancia.

Behcet's disease is a multisystemic vasculitis of unknown origin whose classical triad is oral and genital ulcers and uveitis. Deep venous thrombosis may sometimes be the first manifestation of this disease but is very rare in children. We report the case of a 14-year-old boy with deep venous thrombosis of the leg and a history of severe aphthous gingivostomatitis, perianal ulcers, Henoch-Schonlein purpura, ecchymotic lesions on the lower limbs and intermittent swelling of the left ankle. Complementary tests ruled out the main causes of thrombosis in children. HLA-B5 and B-51 study proved positive, which, together with the patient's history, suggested a diagnosis of Behcet's disease. This disease usually presents around the third decade of life and is very unusual in children. This case is exceptional because thrombosis as an early manifestation of Behcet's disease is very rare in children and because it led to the diagnosis of Behcet's disease in our patient.