The Cochrane collaboration: systematic reviews and their relevance to epilepsy. The Cochrane Epilepsy Network

Network meta-analyses of antiepileptic drug efficacy and tolerability in drug-resistant focal epilepsies: a clinical perspective

PURPOSE

Network meta-analysis (NMA) is a new technique that allows multiple treatment comparisons and provides estimates of effect sizes for all possible pair-wise comparisons. Several NMAs of antiepileptic drug (AED) efficacy and tolerability in individuals with refractory focal epilepsy, however, came to non-specific and, in some cases, divergent conclusions. We review some clinical factors that may be responsible for these inconsistent findings.

RESULTS

A major issue is the small number of individuals included in the meta-analyses with consequent wide confidence intervals and lack of ability to achieve significant results. Further issues are lack of robustness of the measured efficacy outcome-the responder ratio (the percentage of individuals with a >50 % improvement in seizure frequency); the selection of randomized studies (RCTs) included, i.e., the inclusion of studies with heterogeneous populations (children and adults); and inclusion of people treated with different doses of the experimental drug. Some methods of analysing data from RCTs, such as the last observation carried forward (LOCF) analysis, the choice of different phases of the study to compare to baseline, and the year in which the trial was conducted, selectively affect measurement of efficacy outcomes. Titration speed and other methodological aspects selectively affect tolerability.

CONCLUSION

Several factors restrict the analysis of clinically useful estimates of the comparative efficacy of AEDs, while analysis of tolerability may be easier to accomplish.

Truly "rational" polytherapy: maximizing efficacy and minimizing drug interactions, drug load, and adverse effects

While several newer AEDs have study data that support monotherapy usage, most possess FDA indications for adjunctive treatment of partial onset seizures, leading to their initial (and often persistent) clinical use as adjunctive polytherapy for patients with refractory epilepsy. This review considers a practical approach to the appropriate role for polytherapy in epilepsy, presents the evidence for AED polytherapy, reviews the mythic but practically reasonable concept of "rational polytherapy," and concludes with practical strategies for avoiding and employing polytherapy in clinical practice. The appropriate indications for AED polytherapy include transitional polytherapy during titration of a new adjunctive AED toward monotherapy or long-term maintenance AED polytherapy in medically refractory epilepsy.

Concepts in classification and their relevance to epilepsy

The classification of the epilepsies was advanced in order to formalize efforts to identify coherent clinical entities and to develop a standardized set of diagnostic terminology for facilitating communication among workers in the field world-wide. The classification initially was, and still is today, based primarily on description and expert opinion. In the era of genomics, neuroimaging and tremendous technological and scientific advances in the neurosciences, it is time to introduce scientific principles and standards into the classification of the epilepsies. Phylogenetic systematics provides an initial model worth studying in this context. While the classification of species cannot be directly applied to the classification of epilepsy syndromes, three general points can be appreciated. (1) In evolutionary biology, there is an operationalized definition of the end point (a species). There is no such definition of a syndrome. (2) There are rules and criteria for the type of evidence and how it is evaluated to determine whether an entity does or does not represent a separate species. There are currently no such rules or criteria for epilepsy syndromes. (3) There is an underlying model (evolution) that generates the diversity among species. With the possible and only partial exception of the idiopathic generalized epilepsies, there are no models to explain the diversity among the epilepsies. Previously held beliefs and convictions must, in time, give way to dispassionate examination of testable scientific hypotheses examined with rigorously collected scientific evidence. Although current classification is in need of revision, it has also come into common use and has great practical utility. Any changes to its form and to the terminology of the classification must be made only after careful deliberation and broad consensus is reached. The change(s) should be based on agreed upon scientific criteria and processes. Any changes should represent major improvements and not merely incremental steps.