Relation of Lack of Knowledge About Dietary Sodium to Hospital Readmission in Patients With Heart Failure

It has previously been demonstrated that patients with heart failure (HF) in an urban public hospital had significant gaps in knowledge regarding dietary sodium restriction. The objective of this study was to determine what risk factors were associated with such gaps in knowledge and to determine if these gaps in knowledge would increase the risk for HF readmission. A standardized test of sodium knowledge (scored 0 to 10) was administered prospectively to 97 hospitalized patients with HF <48 hours before discharge. The incidence of 90-day hospital readmission for HF was compared between subjects with low dietary sodium knowledge (score 0 to 3) and the remainder of the cohort (score 4 to 10) in univariate and multivariate analyses. Another 48 patients with HF were prospectively recruited, and the dietary sodium knowledge test and a survey of psychosocial and other parameters, including the Test of Functional Health Literacy in Adults, a validated measure of health literacy, were administered. The 90-day readmission rate for HF was 3 times higher in those with low sodium knowledge than in the remainder of the cohort (28% vs 9%, p = 0.02). This association persisted in multivariate models adjusting for potential confounders. Low health literacy, but not other psychosocial parameters, was associated with low dietary sodium knowledge. In conclusion, low dietary sodium knowledge was an independent risk factor for 90-day HF hospital readmission in the urban setting. Deficiency in dietary sodium knowledge is one pathway through which low health literacy leads to adverse outcomes in patients with HF.