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Effectiveness of self management training in type 2 diabetes: a systematic review of randomized controlled trials |
Norris S L, Engelgau M M, Narayan K M |
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Authors' objectives The objectives were: to ascertain the effectiveness of self-management training in type 2 diabetes; to provide summary information to guide diabetes self-management programmes and future quantitative analyses; and to identify further research needs.
Searching MEDLINE, ERIC and CINAHL were searched from January 1980 to December 1999 using the MeSH terms 'Health Education' combined with 'Diabetes Mellitus', including all sub-headings. The search was restricted to English language publications, and abstracts and dissertations were excluded. The following journals were searched manually: Diabetes Care, Diabetes Educator, Diabetes Research and Clinical Practice, Diabetologica, and Diabetic Medicine.
Study selection Study designs of evaluations included in the reviewThe authors state that only reports of randomised controlled trials (RCTs) were included in the review.
Specific interventions included in the reviewThe authors' inclusion criteria specified that interventions in all settings were included. Education could be delivered by any provider type, could involve any medium (written, oral, video, computer), could be individual- or group-based, and could be of any duration and intensity. Studies of multi-component interventions were included only if the effects of the educational component could be examined separately.
The interventions used in the included primary studies were classified by the authors into one of the following categories, according to primary educational focus:
knowledge or information;
lifestyle behaviours, including diet and physical activity;
skill development, including skills to improve glycaemic control such as self-monitoring of blood glucose, as well as skills to prevent and identify complications, e.g. foot care; and
coping skills to improve psychosocial function, including interventions using empowerment techniques or promoting relaxation or self-efficacy.
Studies with a focus on knowledge or information were subclassified by primary type of educational approach: didactic or collaborative.
Participants included in the reviewTo examine as broadly as possible the effectiveness of diabetes education, the inclusion criteria specified that studies should be of participants aged greater than 18 years, with type 2 diabetes and any degree of disease severity and any co-morbidity. Studies of children and adolescents were excluded.
Where reported, the mean age of participants in the included studies was: 33 to 65 years for studies of knowledge or information interventions (didactic); 45 to 66 years for studies of knowledge or information interventions (collaborative); 35 to 68 years for studies of lifestyle and behaviour interventions; 37 to 73 years for studies of skills-teaching interventions; and 50 to 68 years for studies of interventions to improve coping skills.
Outcomes assessed in the reviewThe authors do not specify any inclusion or exclusion criteria relating to outcomes.
The outcomes reported in the included primary studies were classified by the authors, as follows: process measures including knowledge, attitudes and self-care skills; lifestyle behaviours, psychological outcomes and quality of life; glycaemic control; cardiovascular disease risk factors; economic measures and health service utilisation. There was no information on how the outcomes were measured in individual studies.
How were decisions on the relevance of primary studies made?The titles of articles identified by the search were reviewed for their relevance to the effectiveness of diabetes education. The full-text article was retrieved for all those considered potentially relevant. The authors do not state how many of the reviewers performed the selection.
Assessment of study quality Internal validity was assessed using a modified version of the Cochrane approach (see Other Publications of Related Interest) for four types of bias: selection bias, performance bias, attrition bias and detection bias. The criteria were modified since none of the studies fulfilled all the definitions for the absence of bias. In particular, allocation concealment and patient blinding were not used as validity criteria for selection and performance bias, respectively, since the majority of studies made no comment on the allocation process and it is impossible to blind patients in diabetic education studies.
External validity was also assessed. This was considered adequate if the accessible population reasonably represented the target population and study participants were either a random sample of the accessible population or consecutively referred patients, or if no significant differences between participants and nonparticipants were demonstrated at baseline. Studies with populations that consisted of volunteers, which were convenience samples or were otherwise selected by the researchers, may not be generalisable to target populations; the nature of the study populations was, therefore, indicated. The authors do not state how many of the reviewers performed the validity assessment.
Data extraction The authors do not state how the data were extracted for the review, or how many of the reviewers performed the data extraction. It is stated only that data extraction was not blinded. Data were extracted from the primary studies on the number and age range of the participants (where reported), descriptive details of the intervention, follow-up periods (where reported), and outcomes. The authors also recorded some comments on the methodology of individual studies.
Methods of synthesis How were the studies combined?A narrative synthesis was undertaken, organised by outcome category, and results were also grouped similarly in summary tables.
How were differences between studies investigated?The authors do not report a method for assessing study heterogeneity. However, it was stated that included studies were heterogeneous with respect to patient population, educational intervention, outcomes assessed, study quality and generalisability.
Results of the review A total of 72 discrete studies, published in 84 articles were identified. The total number of participants was unclear as the numbers were reported in the outcome categories and the majority of the studies reported more than one outcome.
Studies with short follow-up (less than 6 months) demonstrated positive effects of self-management training on knowledge, frequency and accuracy of self-monitoring of blood glucose, self-reported dietary habits, and glycaemic control. The effects of interventions on lipids, physical activity, weight and blood-pressure (cardiovascular risk factors) were variable. With longer follow-up, interventions that used regular reinforcement throughout follow-up were sometimes effective in improving glycaemic control. Educational interventions that involved patient collaboration may be more effective than didactic interventions in improving glycaemic control, weight and lipid profiles.
No studies demonstrated the effectiveness of self-management training on cardiovascular disease-related events or mortality; no economic analysis included indirect costs; and few studies examined health care utilisation. Performance, selection, attrition, and detection bias were common in the studies reviewed, and external generalisability was often limited.
Cost information Details of intervention costs or health care utilisation effects were reported for eight individual studies. The limited data precludes useful comparisons between interventions.
Authors' conclusions The evidence supports the effectiveness of self-management training in type 2 diabetes, particularly in the short term. Further research is needed to assess the effectiveness of self-management interventions on sustained glycaemic control, cardiovascular disease risk factors, and ultimately, microvascular and cardiovascular disease and quality of life.
CRD commentary The review question was extremely broad, allowing for the examination of any potential type of education and training intervention. The predefined inclusion and exclusion criteria restricted only the age of the participants (all adults) and the design of the included studies (RCTs only). The result was a somewhat confusing collection of very different interventions, applied over a wide range of time scales in potentially very diverse groups of patients, with differing periods of follow-up and outcome measures.
The electronic search strategy, as reported, was crude, and although major journals in the field were handsearched, there was no follow-up checking of the bibliographies of retrieved articles. This, together with the very simple search strategy used and the restrictions on language and publication type, made complete retrieval of the available published articles unlikely. There was no attempt to identify unpublished data, thus raising questions of potential publication bias, which were not addressed by the authors.
The authors stated that the internal validity of primary studies was assessed using Cochrane methodology. The adaptations made to the Cochrane criteria cannot be completely justified; whilst it is true that blinding of patients is generally not possible in studies of educational interventions, there is no obvious reason why criteria regarding the concealment of allocation should be different for this type of study. No details of the method of validity assessment were reported and there was no formal quality score. Although the authors recorded comments on the individual study designs that may be pertinent to the presence of bias, the lack of study details or formal quality scores made this difficult to assess.
Details of the included studies were summarised in tables organised by outcome category. However, there were insufficient information relating to methodological detail and participant details. In addition, since the studies often reported multiple outcome types, and participant numbers were therefore multiply recorded, it was difficult to interpret the participant details reported.
The narrative summary was weak and poorly structured. The summary tables, which contained greater detail, were confusing and overlapped in some elements. The authors highlighted some areas of weakness in the included studies, and their conclusions with respect to the long-term utility of self-management training were suitably cautious. However, given the noted heterogeneity of the included primary studies, firm generalisable conclusions on even the short-term positive impact of self-management training seem difficult to justify.
Implications of the review for practice and research Practice: The authors state that interventions with regular reinforcement are more effective than one-time or short-term education.
Interventions that involve patient participation and collaboration seem to produce somewhat more favourable effects on glycaemic control, weight loss and lipid profiles than didactic ones.
Group education is more effective for lifestyle interventions and seems to be equally effective for interventions focusing on knowledge and self-monitoring of blood glucose.
Research: The authors suggest the following future research topics.
A systematic review of the effectiveness of self-management training interventions in patients with type 2 diabetes using study designs other than RCTs.
Effectiveness studies to define optimal long-term and maintenance interventions with respect to content, frequency and method of delivery.
Studies to further delineate the impact of self-management training on intermediate outcomes, such as self-efficacy, problem-solving and coping skills, and to better define the relationship between these outcomes and behaviour change, glycaemic control and long-term outcomes.
Studies examining the feasibility, effectiveness and cost-effectiveness of population-based self-management training, compared with individual patient-centred training.
A quantitative review of self-management training effectiveness to further examine the heterogeneity of the literature, and the relationships between population characteristics, study design and quality, intervention characteristics and outcomes.
Effectiveness studies focusing on long-term cardiovascular, quality of life and economic outcomes.
Reviewer's statement: In this field, long-term follow-up studies with incidence of diabetic complications as the primary outcome measure are the only truly useful indicator of the clinical utility of an intervention. Intermediate outcome measures, such as short-term glycaemic control or behavioural change, if not sustained, are not predictors of improved prognosis in the long term.
Bibliographic details Norris S L, Engelgau M M, Narayan K M. Effectiveness of self management training in type 2 diabetes: a systematic review of randomized controlled trials. Diabetes Care 2001; 24(3): 561-587 Other publications of related interest Clarke M, Oxman AD, editors. Cochrane Reviewers Handbook 4.1.1. In: The Cochrane Library, Issue 4, 2000. Oxford: Update Software. Updated quarterly.
Indexing Status Subject indexing assigned by NLM MeSH Adaptation, Psychological; Databases, Bibliographic; Diabetes Mellitus, Type 2 /psychology /rehabilitation; Humans; MEDLINE; Patient Education as Topic; Randomized Controlled Trials as Topic; Self Care AccessionNumber 12001000796 Date bibliographic record published 31/03/2002 Date abstract record published 31/03/2002 Record Status This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn. |
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