Interventions to enhance adherence to dietary advice for preventing and managing chronic diseases in adults

Chronic diseases are the leading cause of mortality worldwide. Although the adoption of a healthy diet is recognized as an important component for their prevention and management, many individuals at risk of or having chronic diseases do not adhere to recommended dietary advice. The methods used to facilitate changes in dietary habits through dietary advice (defined in this review as 'interventions') could improve adherence of clients to dietary advice. Therefore, we reviewed trials of interventions aiming to enhance adherence to dietary advice for preventing and managing chronic diseases in adults.

We identified 38 studies involving 9445 participants examining several types of interventions for enhancing adherence to dietary advice for preventing and managing many chronic diseases. The main chronic diseases involved were cardiovascular diseases, diabetes, hypertension, and renal diseases. Interventions shown to improve at least one diet adherence outcome are: telephone follow-up, video, contract, feedback, nutritional tools and more complex interventions including multiple interventions. However, these interventions also showed no difference in some diet adherence outcomes compared to a control/usual care group making the results inconclusive about the most effective intervention to enhance dietary advice. Interestingly, all studies including clients with renal diseases reported at least one diet adherence outcome showing a statistically significant difference favouring the intervention group, no matter which intervention was provided. The majority of studies reporting a diet adherence outcome favouring the intervention group compared to the control/usual care group in the short-term also reported no significant effect at later time points. Studies investigating interventions such as a group session, individual session, reminders, restriction and behaviour change techniques reported no diet adherence outcome showing a statistically significant difference favouring the intervention group. Finally, interventions were generally of short duration, studies used different methods for measuring adherence and the quality of the studies was generally low.

Authors' conclusions: 

There is a need for further, long-term, good-quality studies using more standardized and validated measures of adherence to identify the interventions that should be used in practice to enhance adherence to dietary advice in the context of a variety of chronic diseases.

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Background: 

It has been recognized that poor adherence can be a serious risk to the health and wellbeing of patients, and greater adherence to dietary advice is a critical component in preventing and managing chronic diseases.

Objectives: 

To assess the effects of interventions for enhancing adherence to dietary advice for preventing and managing chronic diseases in adults.

Search strategy: 

We searched the following electronic databases up to 29 September 2010: The Cochrane Library (issue 9 2010), PubMed, EMBASE (Embase.com), CINAHL (Ebsco) and PsycINFO (PsycNET) with no language restrictions. We also reviewed: a) recent years of relevant conferences, symposium and colloquium proceedings and abstracts; b) web-based registries of clinical trials; and c) the bibliographies of included studies.

Selection criteria: 

We included randomized controlled trials that evaluated interventions enhancing adherence to dietary advice for preventing and managing chronic diseases in adults. Studies were eligible if the primary outcome was the client’s adherence to dietary advice. We defined 'client' as an adult participating in a chronic disease prevention or chronic disease management study involving dietary advice.

Data collection and analysis: 

Two review authors independently assessed the eligibility of the studies. They also assessed the risk of bias and extracted data using a modified version of the Cochrane Consumers and Communication Review Group data extraction template. Any discrepancies in judgement were resolved by discussion and consensus, or with a third review author. Because the studies differed widely with respect to interventions, measures of diet adherence, dietary advice, nature of the chronic diseases and duration of interventions and follow-up, we conducted a qualitative analysis. We classified included studies according to the function of the intervention and present results in a narrative table using vote counting for each category of intervention.

Main results: 

We included 38 studies involving 9445 participants. Among studies that measured diet adherence outcomes between an intervention group and a control/usual care group, 32 out of 123 diet adherence outcomes favoured the intervention group, 4 favoured the control group whereas 62 had no significant difference between groups (assessment was impossible for 25 diet adherence outcomes since data and/or statistical analyses needed for comparison between groups were not provided). Interventions shown to improve at least one diet adherence outcome are: telephone follow-up, video, contract, feedback, nutritional tools and more complex interventions including multiple interventions. However, these interventions also shown no difference in some diet adherence outcomes compared to a control/usual care group making inconclusive results about the most effective intervention to enhance dietary advice. The majority of studies reporting a diet adherence outcome favouring the intervention group compared to the control/usual care group in the short-term also reported no significant effect at later time points. Studies investigating interventions such as a group session, individual session, reminders, restriction and behaviour change techniques reported no diet adherence outcome showing a statistically significant difference favouring the intervention group. Finally, studies were generally of short duration and low quality, and adherence measures varied widely.

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