The Dietray Intervention Study in Children (DISC)

Objectives:

The Dietary Intervention Study in Children (DISC) trial was initiated in 1987 and sought to evaluate the efficacy and safety of a lipid lowering diet in 8 to 10 year old children after at least 3 years of followup. The primary efficacy outcome was low-density lipoprotein (LDL) cholesterol. Secondary efficacy outcomes were total cholesterol, high-density lipoprotein (HDL), cholesterol, and triglycerides. Primary safety outcomes were height and serum ferritin. Secondary safety outcomes included serum zinc, folate, retinol, and albumin. The trial was extended, with continuation of the intervention, albeit at a diminished intensity, to follow the children for an additional 4 years, resulting in a mean of 7.4 years of total follow-up, when the participants were on average 17 years old.

Background:

A growing body of evidence suggests that atherosclerosis is a long term process that may begin early in childhood. Autopsy studies have revealed coronary fatty streaks in obese children, and other studies have shown that blood cholesterol levels show a fairly high correlation as children age into young adults. Familial clustering of lipid levels provide further rationale for intervention studies aimed at reducing cholesterol levels in children. Previous studies have demonstrated the efficacy of dietary interventions in adults in reducing blood cholesterol levels; however, the safety and efficacy of dietary interventions in growing children were less clear, and previous studies were only short-term interventions.

Subjects:

The DISC study was a multicenter, randomized controlled trial that enrolled 663 prepubertal children aged 8 to 10 years who had elevated LDL-cholesterol levels (80th-98th percentile based on age-gender distributions from the Lipid Research Clinics). The children were assigned at random to an intervention or usual care group. Fifty-five percent of the participants were male. The intervention group attended a series of group and individual sessions where the children and their families were counseled to follow a diet containing 28 percent of calories as total fat, less than 8 percent of calories from saturated fat, dietary cholesterol intake less than 75 mg/1000 kcal, and up to 9% of calories from polyunsaturated fat. The diets were designed to meet nutritional requirements of growing children. The usual care group was provided a packet of educational publications on heart-healthy eating that were generally available to the public. The primary endpoint was change in LDL-cholesterol after three years of followup, and subsequently after 7 years of follow-up.

Conclusions:

After three years of followup, LDL cholesterol decreased by an average of 15.4 mg/dL in the intervention group and 11.9 mg/dL in the usual care group. This difference of 3.3 mg/dL (adjusted for baseline levels and gender) was significant (p=0.02). There were no significant differences between the two groups in adjusted mean height or serum ferritin. There were no significant differences in secondary safety measures as well. (JAMA, 1995; 273(18):1429-35). After 7 years of followup, the difference in LDL-cholesterol between the two treatment groups decreased to 2.0 mg/dL, which was no longer significant. There continued to be no significant differences in an adverse direction in primary or secondary safety measures. (Pediatrics, 2001;107(2):256-264).