Effectiveness of Dietetic Consultations in Primary Health Care: A Systematic Review of Randomized Controlled Trials

Background A dietetic consultation is a structured process aimed at supporting individual patients to modify their dietary behaviors to improve health outcomes. The body of evidence on the effectiveness of nutrition care provided by dietitians in primary health care settings has not previously been synthesized. This information is important to inform the role of dietitians in primary health care service delivery. Objective The aim of this systematic review was to evaluate the evidence of the effectiveness of individual consultations provided exclusively by dietitians in primary care to support adult patients to modify dietary intake and improve health outcomes. Study design ProQuest Family Health, Scopus, PubMed Central, Medline, the Cumulative Index to Nursing and Allied Health Literature, and Cochrane databases were searched for English language systematic reviews or randomized controlled trials published before October 2016. The key terms used identified the provision of nutrition care exclusively by a dietitian in a primary health care setting aimed at supporting adult patients to modify dietary behaviors and/or improve biomarkers of health. Interventions delivered to patients aged younger than 18 years, in hospital, via telephone only, in a group or lecture setting, or by a multidisciplinary team were excluded. The methodologic quality of each study was appraised using the Cochrane Risk of Bias tool and the body of evidence was assessed using the Academy of Nutrition and Dietetics Evidence Analysis Manual. Main outcome measures Outcomes included the effectiveness of dietetic interventions in terms of anthropometry, clinical indicators, and dietary intake. A statistically significant between-group difference was used to indicate intervention effectiveness (P<0.05). Results Twenty-six randomized controlled studies met eligibility criteria, representing 5,500 adults receiving dietetic consultations in a primary care setting. Eighteen of 26 included studies showed statistically significant differences in dietary, anthropometric, or clinical indicators between intervention and comparator groups. When focusing specifically on each study's stated aim, significant improvements favoring the intervention compared with control were found for the following management areas: glycemic control (four out of four studies), dietary change (four out of four studies), anthropometry (four out of seven studies), cholesterol (two out of eight studies), tri-glycerides (one out of five), and blood pressure (zero out of three) studies. Conclusions Dietetic consultations for adults in primary care settings appear to be effective for improvement in diet quality, diabetes outcomes (including blood glucose and glycated haemoglobin values), and weight loss outcomes (eg, changes in weight and waist circumference) and to limit gestational weight gain (Grade II: Fair evidence). Research evaluated in this review does not provide consistent support for the effectiveness of direct dietetic counseling alone in achieving outcomes relating to plasma lipid levels and blood pressure (Grade III: Limited evidence). Therefore, to more effectively control these cardiovascular disease risk factors, future research might explore novel nutrition counseling approaches as well as dietitians functioning as part of multidisciplinary teams.