A randomised controlled trial of a dietary advice program for relatives of heart attack victims

OBJECTIVE: To compare two interventions for reducing dietary fat intake in first degree relatives of recent heart attack victims. DESIGN: A randomised controlled trial comparing a low cost mail-out advice program; referral to a general practitioner (GP); and no intervention (control group). PARTICIPANTS: Adult children or siblings, aged less than 70 years, of survivors of definite or suspected heart attack who had been admitted to hospitals in the Lower Hunter Region of New South Wales. MAIN OUTCOME MEASURES: Dietary fat intake (evaluated with a validated short questionnaire) and measurement of blood cholesterol levels at six months. RESULTS: Of the 342 relatives who participated (36% of those invited), 109, 120 and 113, respectively, were randomly assigned to receive a mail-out intervention, advice from their GP or to be part of a control group. The six-month follow-up questionnaire was completed by only 59% of those in the mail-out intervention group compared with 71% of the GP group and 77% of the control group. Younger participants, cigarette smokers and children (compared with siblings) were less likely to return a follow-up questionnaire. The mail-out group showed a statistically significant 20% reduction in self-reported dietary fat intake, but this was not seen in either the GP group or the controls. The low response rate meant the study had insufficient power to detect hypothesised changes in blood cholesterol. CONCLUSION: Because of the poor response rate and possible biases from a differential response to follow-up, we conclude that this low intensity intervention for relatives of people with recent heart attack produces only a modest improvement in reported dietary fat intake. Alternative strategies may be more effective in reducing the risk of heart disease.