THE EFFECT OF A HOUSEHOLD PARTNER AND HOME URINE MONITORING ON ADHERENCE TO A SODIUM RESTRICTED DIET

To evaluate the effects of social support and home urine monitoring on success with dietary sodium reduction, 114 essential hypertensive adults and a household partner were recruited. One of the pair was required to be the food preparer. Patients with their partners were randomly assigned to either an active or passive partner condition. During dietary counseling in the active condition, both patients and partner were involved in instructions to change their diet to reduce their daily sodium intake to 80 mmol or less. In the passive condition, the partners were present during the dietary counseling, but no effort was made to involve them directly in the instruction or to encourage them to make personal dietary changes. Patients and active partners collected two 24-hr urine collections between each of the first two counseling sessions and received feedback on the sodium results by a telephone call. In the passive partner condition, only patients collected urine for feedback. At the end of the 6 week instructional period, all patients and partners collected a 24-hr urine and had their blood pressure assessed. Half of each group was also randomly assigned to have access to a system for periodic home-monitoring of urine for sodium content during a 3-month period beginning at week 6 of the study (immediate). The delayed feedback group received the home-monitoring system three months after completion of the dietary instruction. All patients, but only active partners, used the feedback system during their assignment periods and collected a 24-hr urine monthly between 6 and 30 weeks of the study. Passive partners did not receive feedback on their urinary sodium excretion and collected a 24-hr urine only at weeks 6, 18 and 30. Neither the feedback system not the instructional participation status of the partner made a significant difference in dietary compliance. After dietary instruction, all groups significantly (P < 0.01) reduced their sodium intake for the duration of the study from baseline values. Regression was observed between 6 and 18 weeks, but at 30 weeks sodium excretion still remained significantly less (P < 0.05) than baseline. The sodium content of patients' and partners' urines were significantly correlated before and during the study (r = 0.25-0.37; P < 0.02), independent of their experimental condition. The dietary instruction was able to produce changes in eating habits irrespective of the active participation of the partner in the instructional process. Early provision of self-informed feedback monitoring did not appear to enhance adherence. Individuals most likely to comply were lower-weight females, white or those who had a lower sodium intake at baseline. This study shows that inclusion of the food preparer in face-to-face dietary instruction and telephone feedback on urine results was sufficient to produce reduction in sodium intake and help many sustain that reduction for the duration of the study. © 1991.