Children with a previously confirmed diagnosis of refractory epilepsy, from the Department of Neurology of the Children’s Hospital of Chongqing Medical University in China were enrolled in the study. None of the patients had received KD treatment before and their physicians judged them as suitable to undergo KD treatment. Epilepsy and seizure types were classified according to the recommendations of the International League Against Epilepsy (ILAE) 2010 [29]. All patients underwent metabolic assessment (urinary organic acid chromatography and blood amino acid chromatography). The exclusion criteria were children with contraindications to the KD [1]. Our patients were taking some anti-epileptic drugs (AEDs). The patients did not routinely undergo an assessment of cardiac function before taking AEDs. We also assessed the additional effects of AEDs on cardiac function among the same number of age and gender matched children were selected as the control group, which received a normal diet and did not receive any drugs. Table 1 shows the diagram of visits.
Table 1
Groups | Time point | T0 Day 0 | T1 1 months | T2 3 months | T3 6 months | T4 12 months |
Experimental group | Data collection | × | × | × | × | × |
Physical examination | × | × | × | × | × |
Dietary questionnaires | × | × | × | × | × |
Color Doppler imaging | × | | × | | |
Total cholesterol | × | × | × | × | × |
Triglyceride | × | × | × | × | × |
High-density lipoprotein cholesterol | × | × | × | × | × |
Low-density lipoprotein cholesterol | × | × | × | × | × |
Blood ketones | × | × | × | × | × |
Blood glucose | × | × | × | × | × |
Control group | Data collection | × | | × | | |
Physical examination | × | | × | | |
Dietary questionnaires | × | | × | | |
Color Doppler imaging | × | | × | | |
The study protocol was approved by the Institutional Review Board of the Children’s Hospital of Chongqing Medical University. The participants’ parents were informed of the risks/benefits of study participation and provided consent for participation in the present study.
A non-fasting gradual initiation protocol of 2:1 KD therapy was initiated at the hospital under the guidance of a dietician.
Blood beta-hydroxybutyrate level measurements made using whole blood samples obtained at the fingertip were used to evaluate patients’ ketone statuses. Ketone levels were measured using the FreeStyle Optium Neo Blood Glucose and Ketone Monitoring System (Abbott Diabetes Care Inc., USA). We monitored blood ketone levels once every 6 hours when the patients were hospitalized. KD ratios (fat: carbohydrates + protein) changed between 1:1 and 4:1, depending on individual patients’ blood ketone levels and frequency of seizures. Blood ketone levels reached target levels within 2–10 days with a mean of 4.7 days for all patients. The children were discharged and followed-up at clinic visits when ketone concentrations stabilized between 2 and 5 mmol/L [30, 31] and there were no adverse effects. After discharge, ketone levels were monitored once daily for the first month and weekly thereafter.
Parents reported blood ketone levels, glucose levels, seizure frequency, and any adverse events. At clinic visits, the KD ratio was adjusted depending on blood ketone levels and the degree of seizure control. Caloric intake was adjusted to maintain the ideal body weight and height, based on the patient’s height and weight gain or loss.
Patients were observed for 3 months during which we assessed the therapeutic effect of the KD [1]. For patients among whom the KD therapy worked, we assisted them with reducing their AEDs gradually, one at a time. Parents were asked about the effects of each AED, and if an AED led to significantly worse seizures, we considered reducing the dose of that drug first. Next, we reduced the doses of drugs which had little to no effect. Finally, we eliminated drugs that were effective at the beginning, but were unable to maintain the effect.
Data on the variables were collected by the assessment of ventricular systolic and diastolic functions using color Doppler imaging. We collected data regarding sex; age; height; weight; ejection fraction; fractional shortening; ratio of peak velocity blood flow from gravity in early diastole (the E wave) to peak velocity flow in late diastole caused by atrial contraction (the A wave) (E/A); and the levels of total cholesterol, triglyceride, HDL cholesterol, and low-density lipoprotein (LDL) cholesterol.
Since there are no human studies about the effect of the KD on systolic and diastolic function, 20 people were assessed in a preliminary experiment to explore the positive and negative cardiovascular effects. With EF (systolic function) as the observed value (n = 20, EF at day 0 was 66.95%±8.17%, EF at 3 months was 71.00%±3.85%, the change of EF was 4.05%±8.70%), considering α = 0.05, a two-sided Z value, a one-sided β value, and 1–β = 0.9, the study sample size was determined to be 48. When the estimated loss to follow-up rate was considered as 10%, the required sample size would be 53.
The independent t-test and chi-squared test were performed to determine group differences in baseline characteristics. Cardiac ultrasonography values were compared using the generalized estimating equation. Repeated-measures analyses of variance were used to determine changes in lipid levels. Multiple linear regression analysis was used to assess the effects of other factors (sex, age, BMI, valproic acid dose, and blood ketone level) on cardiac function. All data analyses were performed using SPSS version 18 (IBM Corp., Armonk, NY, USA). Analysis items with p value < 0.05 were considered statistically significant.