The ketogenic diet which favors lipid intake (60 to 90% of total caloric intake, to the detriment of carbohydrates) constitutes a serious therapeutic option in the management of epilepsy, particularly when it is a drug-resistant form. . Four ketogenic diets currently dominate: classic (RCC), modified Atkins (RAM), enriched with medium chain triglycerides (RCT) and that characterized by the lowest glycemic index (RIGF).
Of these diets, it is the first that is both the most restrictive and the least palatable, while being the most likely to induce ketosis. Another diet was recently introduced in the United Kingdom with modifications which earned it the name MAD ( Modified Ketogenic Diet). Compliance with these diets is far from optimal, particularly in the long term, despite the progress made since their implementation in recent decades.
Certain adverse events, various psychosocial factors (such as reduced participation in daily social activities) or even the restrictive and monotonous nature of diets can lead to their abandonment. Compliance with ketogenic diets has only rarely been studied in a standardized and quantitative manner, particularly in the indication of drug-resistant epilepsy in children and adolescents. The same goes for compliance which, in certain studies, replaces observance, understandable confusion between the two terms being common.
A meta-analysis: 22 methodologically diverse studies
This observation is of great interest to a systematic review of the international literature coupled with a meta-analysis and carried out in compliance with the methodological recommendations of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses method) which is a guarantee of quality. The following electronic databases were used: PubMed, Scopus, Web of Science, Lilacs and Science Direct. Articles published in English, Italian, Spanish or Portuguese were included.
Observational, therefore non-controlled, studies were accepted, in addition to randomized trials or other open clinical studies. Risk of bias, study quality and heterogeneity were systematically assessed.
In total, the meta-analysis covered 22 studies (bringing together less than 900 patients of varying ages), more than half of which (n=12) were of average quality. Heterogeneity in diagnosis and measurement of adherence (or compliance) has somewhat complicated the comparison of results. The average observance (or compliance) rates varied little according to age, being 71.5%, 66% and 63.9% respectively among children, adolescents and adults.
On the other hand, these rates varied significantly depending on the duration of follow-up: at the end of 6 months, the rate was 79.7%, falling to 66.7% after 24 months to finish at 37.7% at 36th month of follow-up. Poor compliance with these diets has most often been attributed to lack of control of epileptic seizures, adverse events, rejection of food, or difficulties caused by ad hoc meal preparation. Dietary restrictions, lack of motivation, low parental compliance or even the additional cost linked to certain food choices are other factors which have led to a weakening of compliance.
This review of the international literature first highlights the scarcity of quality studies making it possible to evaluate compliance with the ketogenic diet in patients with drug-resistant epilepsy. Furthermore, it is clear that, in the few studies selected, the evaluation tools used are far from being standardized.
In children and adolescents, it appears that compliance is conditioned by the parents’ attitude towards these diets, a notion which deserves to be taken into account in the development of therapeutic strategies. Controlled studies involving larger numbers of people are clearly welcome.
