Intervention Presentation On Diabetes

Systematic Review or Meta-analysis

Effectiveness of group-based self-management education

for individuals with Type 2 diabetes: a systematic review

with meta-analyses and meta-regression

K. Odgers-Jewell1 , L. E. Ball2, J. T. Kelly1, E. A. Isenring1, D. P. Reidlinger1 and R. Thomas3

1Faculty of Health Sciences and Medicine, Bond University, 2Menzies Health Institute Queensland, Griffith University and 3Centre for Research in Evidence-Based

Practice (CREBP), Bond University, Gold Coast, Australia

Accepted 17 February 2017

Abstract

Aims Patient education for the management of Type 2 diabetes can be delivered in various forms, with the goal of

promoting and supporting positive self-management behaviours. This systematic review aimed to determine the

effectiveness of group-based interventions compared with individual interventions or usual care for improving clinical,

lifestyle and psychosocial outcomes in people with Type 2 diabetes.

Methods Six electronic databases were searched. Group-based education programmes for adults with Type 2 diabetes

that measured glycated haemoglobin (HbA1c) and followed participants for ≥ 6 months were included. The primary outcome was HbA1c, and secondary outcomes included fasting blood glucose, weight, body mass index, waist

circumference, blood pressure, blood lipid profiles, diabetes knowledge and self-efficacy.

Results Fifty-three publications describing 47 studies were included (n = 8533 participants). Greater reductions in HbA1c occurred in group-based education compared with controls at 6–10 months [n = 30 studies; mean difference (MD) = 3 mmol/mol (0.3%); 95% confidence interval (CI): �0.48, �0.15; P = 0.0002], 12–14 months [n = 27 studies; MD = 4 mmol/mol (0.3%); 95% CI: �0.49, �0.17; P < 0.0001], 18 months [n = 3 studies; MD = 8 mmol/mol (0.7%); 95% CI: �1.26, �0.18; P = 0.009] and 36–48 months [n = 5 studies; MD = 10 mmol/mol (0.9%); 95% CI: �1.52, �0.34; P = 0.002], but not at 24 months. Outcomes also favoured group-based education for fasting blood glucose, body weight, waist circumference, triglyceride levels and diabetes knowledge, but not at all time points.

Interventions facilitated by a single discipline, multidisciplinary teams or health professionals with peer supporters

resulted in improved outcomes in HbA1c when compared with peer-led interventions.

Conclusions Group-based education interventions are more effective than usual care, waiting list control and individual

education at improving clinical, lifestyle and psychosocial outcomes in people with Type 2 diabetes.

Diabet. Med. 34, 1027–1039 (2017)

Introduction

Patient education is an integral and vital component of

successful diabetes care [1–3]. The main goal of diabetes

patient education is to promote and support positive self-

management behaviours to optimize metabolic control,

improve long-term diabetes outcomes and quality of life

(QOL), prevent complications, and reduce morbidity and

mortality, while remaining cost-efficient [1,4]. Group-based

education for individuals with Type 2 diabetes may be more

cost-effective and efficient than individual education, due to

the reduced time and funding required to educate numerous

people in one sitting [5]. The potential advantages of group-

based education interventions over individual visits include

time for the provision of more detailed information,

decreased time demands on health workers, easy incorpora-

tion of families and carers, and facilitation of discussions and

support from others facing the same challenges [6,7].

Clearly, the use of group-based education warrants further

investigation.

Three previous systematic reviews included group educa-

tion for Type 2 diabetes. A Cochrane systematic review

assessed the effects of group-based training on clinical,

lifestyle and psychosocial outcomes in people with Type 2

diabetes compared with routine treatment, waiting list

control or no intervention [8]. The review favoured group-Correspondence to: Kate Odgers-Jewell. E-mail: kodgersj@bond.edu.au

ª 2017 Diabetes UK 1027

DIABETICMedicine

DOI: 10.1111/dme.13340

 

 

based education, finding significant improvements in HbA1c levels, body weight, systolic blood pressure (BP), and fasting

blood glucose (FBG), a decreased need for diabetes medica-

tion and increased diabetes knowledge [8]. A subsequent

publication in 2012, updating the original Cochrane review,

supported the findings of the former, favouring group-based

education, with significant reductions in HbA1c, FBG and

body weight, and improvements in diabetes knowledge

compared with controls [6]. Another recent systematic

review [9] assessed the effect of diabetes self-management

education and support methods, providers, duration and

contact time on glycaemic control in adults diagnosed with

Type 2 diabetes. The review included individual, group-

based, combination and remote interventions for the man-

agement of Type 2 diabetes, with results suggesting that a

combination of individual and group-based education was

most effective at improving HbA1c (median 9.6 mmol/mol;

0.88%) when compared with controls [9].

These previous reviews had limitations. First, the searches

are outdated and the number of published studies for group-

based diabetes interventions has increased substantially since

their completion. High heterogeneity precluded meta-analyses

for several of the main outcomes, which were completed for

just two studies [6,8]. Although both reviews found clinical

and statistically significant changes in health outcomes, the

exact mechanism or ‘active ingredient(s)’ of these complex

interventions were not identified [6,8]. Both reviews only

conducted follow-up analyses of the primary outcome up to

2 years from baseline [6,8]. The quality of the previous reviews

was assessed using ‘A Measurement Tool to Assess Systematic

Reviews’ (AMSTAR), a reliable and valid method for assessing

the methodological quality of systematic reviews [10]. The

AMSTAR scores were categorized in line with previous

research [11,12], with scores of 0–4 classified as ‘low quality’,

5–8 classified as ‘moderate quality’, and 9–11 classified as

‘high quality’. The Cochrane review [8] was assessed as a high-

quality review (score: 9/11). This review lacked an assessment

of publication bias and conflict of interest for the included

studies. The review by Steinsbekk et al. [6] was assessed as a

moderate quality review (score: 5/11); no protocol was

available, grey literature and publication bias were not

considered, a list of excluded studies was not provided, an

assessment of conflict of interest for included studies was not

explored and the scientific quality of the included studies was

not used appropriately in formatting conclusions. The review

by Chrvala et al. [9] was assessed as a moderate quality review

(score: 7/11); grey literature and publication bias were not

considered, a list of excluded studies was not provided and

conflict of interest for included studies was not explored. The

review had various limitations including: restricting included

studies to English-language publications, including only ran-

domized controlled trials, including interventions for individ-

uals with either/both Type 1 and/or Type 2 diabetes, and an

inability to conduct meta-analyses [9].

Despite these systematic reviews providing evidence of

effectiveness, group-based education interventions are often

complex and the characteristics of the interventions vary

greatly, for example, in the number of contact hours, number

of sessions, number and characteristics of participants, group

facilitator(s) or educator (s) qualifications, facilitator training,

theoretical framework, and whether family, friends or carers

can attend [6,8]. Health professionals may deter from group-

based education because the essential attributes for a success-

ful group-based education programme are unknown. Fur-

thermore, no specific evidence-based practice guidelines for

group-based education in Type 2 diabetes have been identified

internationally, inevitably resulting in wide variations in the

programmes offered, and creating difficulty in the interpreta-

tion of evidence and its translation to a practice setting.

This systematic review builds upon two of the previous

reviews [6,8] and seeks to update the evidence for the

effectiveness of group-based interventions for Type 2 dia-

betes management and investigate key attributes for success-

ful group programmes. It was hypothesized that:

� group-based interventions for Type 2 diabetes would have greater reductions in HbA1c compared with controls in the

short (6 months) and long (> 12 months) term;

� group-based interventions for Type 2 diabetes would improve body weight, body mass index (BMI), waist

circumference, FBG, BP, lipid profiles, diabetes knowledge

and self-efficacy, compared with controls;

� variations in effect sizes could be attributed to study design (i.e. setting, control group, educator), and intervention

characteristics (i.e. number of participants, intervention

length, number of contact hours).

Methods

The study was registered with the International Prospective

Register of Systematic Reviews PROSPERO (CRD420150

27785).

What’s new?

• We present a comprehensive up-to-date review of the

evidence for the effectiveness of Type 2 diabetes group-

based interventions. This is the first review in the area

to complete a meta-regression.

• We report statistically significant results for improving

HbA1c, fasting blood glucose, body weight, waist

circumference, triglycerides and diabetes knowledge,

but clinical improvement is more nuanced.

• Group-based interventions facilitated by a single disci-

pline, multidisciplinary teams or health professionals

with peer supporters appear to be more effective at

improving HbA1c than peer-led interventions.

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Data sources and search strategy

A systematic literature search was performed to retrieve

publications on group-based education for the management

of Type 2 diabetes in adults. The search was completed in

three parts. First, electronic databases, including PubMed,

the Cochrane Central Register of Controlled Trials (CEN-

TRAL), Embase, CINAHL, PsycINFO and ERIC, were

searched from commencement of records to 22 September

2015 (File S1). Second, hand searches of reference lists from

previous reviews were completed [6,8]. Finally, the included

studies were cross-referenced with the results of an updated

search by the authors of the most recent review including

studies up to May 2012 (email correspondence). No

language or date restrictions were applied. Abstract-only

publications were excluded and duplicate articles were

removed prior to title and abstract screening.

Inclusion criteria and study selection

Group-based education intervention studies for participants

diagnosed with Type 2 diabetes that reported randomized

controlled trials, cluster randomized trial or controlled

clinical trial study designs were included. Studies were

included if the described intervention met the following

criteria: adults aged ≥ 18 years; face-to-face, educative group-based interventions (including those with occasional

adjunct individual consultations) for people with Type 2

diabetes; a minimum of four participants and may include

family and friends for support; a minimum of one session

lasting for 1 h; groups delivered in primary or secondary care

compared with a control or comparison group (usual care,

waiting list control or individual intervention); and studies

that measured HbA1c at both baseline and 6 or more months

from baseline. Studies were excluded if participants were

pregnant women or were diagnosed with Type 1 diabetes, or

interventions provided education in individual consultations,

included only exercise prescriptions without education or

were not conducted face-to-face.

All studies were screened against the eligibility criteria by

two independent reviewers (KOJ and LEB) using reference

manager software EndNote (Thomson Reuters, New York,

NY, USA). Conflicts were resolved by discussion between

them. Studies that met the inclusion criteria or did not

include sufficient information for screening in the title and

abstract, were included for full-text review. Full-text versions

of these articles were obtained and screened independently.

Authors were contacted for missing data up to three times by

email if the missing data affected assessment of the study’s

eligibility, and were excluded if contact could not be made.

Data extraction and quality assessment

Data extraction was completed by the first author (KOJ) and

confirmed for accuracy by an independent reviewer (JTK).

Data extracted included: general information on the study

design, trial characteristics, intervention details, participant

characteristics, outcome measures, results and information

for appraising the risk of bias. Study quality was assessed

using the Cochrane risk of bias tool [13] by two independent

reviewers (KOJ and LEB). Disagreements were resolved

through discussion. Risk of bias was ranked as low, unclear

or high depending on whether a study had any element of

bias (e.g. selection, performance, detection, attrition, report-

ing and other bias).

Data synthesis and analysis

Descriptive data from the included studies were summarized.

Data were meta-analysed if the same measurement was used

across three or more studies at the same time point. The

primary outcome measure was change in HbA1c in group-

based education vs. control. The secondary outcome mea-

sures were changes in FBG, weight, BMI, waist circumfer-

ence, BP, total cholesterol, LDL-cholesterol, HDL-

cholesterol, triglycerides, diabetes knowledge and self-effi-

cacy. Prior to the meta-analyses, studies reporting FBG or

lipid profile measures in mg/dl were converted to mmol/l;

those reporting weight in lb were converted to kg.

Summaries of effect estimates were calculated by meta-

analysis using the DerSimonian and Laird random effects

model in Review Manager (RevMan, v. 5.3) [14]. Continu-

ous data using the same measures were analysed with a

weighted mean difference in outcomes between the interven-

tion and control groups, whereas continuous data collected

using a variety of measures were assessed using the standard

mean difference (SMD). Heterogeneity was assessed using

the I-squared statistic and reported following the Cochrane

Handbook [13].

Mean differences (MD) and 95% confidence intervals (CI)

were calculated in RevMan and standard error was calcu-

lated in Microsoft� Excel using the 95% CIs for the meta-

regression. Separate analyses for the effect of group-based

interventions on HbA1c were performed for the following

subgroups: control groups, delivery setting, insulin therapy,

type of educator(s), training of educator(s), baseline HbA1c levels, theoretical model and intervention content, materials,

length, number of sessions, contact time, number of partic-

ipants and the inclusion/exclusion of family and/or friends.

Sensitivity analyses were conducted to explore the influ-

ence of study quality (overall risk of bias and reporting bias),

on HbA1c outcomes (as measured closest to intervention

completion) and heterogeneity. Reporting bias and selective

outcome reporting were chosen for the sensitivity analysis

because studies that did not report the pre-specified outcomes

or failed to include the results for an expected outcome may

be reporting only results supporting the studies’ aims or

hypotheses. We also examined potential influences on the

primary outcome for studies that had differences in HbA1c at

baseline, large (defined as > 10%) compared with small

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attrition (defined as < 10%), and studies published in non-

English journals due to potential publication bias.

Subgroup analyses were also conducted to examine the

effects of different educators (health professionals, health

professionals with peer support, peer or lay-persons), disci-

plines (single discipline compared with multidiscipline) and

studies that included participants taking (and not taking)

insulin on the primary outcome HbA1c.

In addition, a univariate meta-regression was completed to

explore potential associations between the size of effect and

varying study and intervention characteristics [15]. Variables

were similar to those explored in the subgroup analyses. A

meta-regression was performed using Stata statistical soft-

ware [16].

Results

Study selection

The search identified 14 016 results, from which 9764

publications were screened against the selection criteria,

leaving 298 studies for full-text review (Fig. 1). Forty-seven

studies reported in 53 publications were included in the

systematic review (references provided in File S2).

A total of 8533 participants were included in the 47 studies

(intervention group n = 4416, control group n = 4117). The

mean age of participants was 60 years. Men made up 44% of

participants in both the intervention (1917 of 4383) and

control (1799 of 4086) groups. Three of the 47 included

studies (6%) recruited only women. Known duration of

diabetes was reported by 29 of the 47 studies (62%). Mean

duration of diabetes was 8.9 years for participants in the

intervention group, and 9.4 years in the control group. Mean

HbA1c level at baseline was 67 mmol/mol (8.3%) for both

groups and ranged between 39 and 111 mmol/mol (5.7%–

12.3%) for the intervention group and between 40 and

115 mmol/mol (5.8%–12.7%) for the control group. In 38

(81%) studies, the mean HbA1c was > 53 mmol/mol (7%)

for both the intervention and control groups.

Study characteristics

Study characteristics are detailed in Table S1. Of the 47

studies included, 40 reported the results of randomized

controlled trials, four reported results of controlled clinical

trials and three reported the results of cluster randomized

controlled trials. Most of the studies were carried out in the

USA (18; 38%), the UK (6; 13%) and Italy (5; 11%). Forty-

two of the studies were published in English, two in Spanish

[17,18], two in Italian [19,20] and one in Dutch [21]. The

studies were published between 1988 and 2015, and the

length of follow-up was 6–60 months from baseline.

Records identified through

Id en tif ic at io n

S cr ee ni ng

E lig ib ili ty

In cl ud ed

Records after duplicates removed

database searching (n = 14016)

(n = 9767)

Records screened

Full-text articles

Studies included in quantitative synthesis

(meta-analysis)

assessed for eligibility

(n = 9767) Records excluded

Full-text articles excluded

Did not meet intervention criteria (n= 180)

Abstract only (n= 29) Protocol/ commentary (n= 8)

Not an RCT (n= 34)

(n = 9469)

(n = 251):

(n = 298)

(n = 47)

Additional records identified through other sources

(n = 3)

FIGURE 1 Stages of study identification

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Intervention characteristics varied in materials provided,

discipline(s) of group educators and theoretical model used,

as summarized in Table S2. Studies were conducted pre-

dominantly in primary care settings (32; 68%), with 15

(32%) of the studies delivered in secondary or tertiary care

settings, for example, hospital diabetes centres or tertiary

hospitals. Four publications [22–25] reported on multiple

arm studies.

Study quality

Most studies were classified as having a moderate (31) or

high (12) risk of bias, with four studies classified as having a

low risk of bias (Table S3). Of the six risk of bias items,

allocation concealment (selection bias), blinding of partici-

pants and personnel (performance bias), and blinding of

outcome assessment (detection bias) were the least consis-

tently described or were generally poorly conducted in the

included studies (Fig. S1).

Overall effects of group-based interventions for HbA1c

A meta-analysis was conducted to assess the effect of group-

based education compared with control for all 47 included

studies (n = 7055) using the measure of HbA1c at the time

point closest to the completion of each group-based educa-

tion intervention (Fig. 2). Overall, compared with control,

group-based intervention was effective in reducing HbA1c by

4 mmol/mol (0.3%) (95% CI: �0.51, �0.17; P < 0.0001; I2 = 84%). Heterogeneity was statistically significant and

potential reasons for this were explored with sensitivity

analyses.

The results of the meta-analyses for HbA1c and secondary

outcome measures at various time points are provided in

Table 1.

Group-based interventions significantly reduced HbA1c post intervention at most time points compared with

controls. HbA1c was significantly reduced at 6–10 months

post baseline [n = 30 studies; MD = 3 mmol/mol (0.3%);

95% CI: �0.48, �0.15; P = 0.0002; I2 = 65%], 12– 14 months post baseline [n = 27 studies; MD = 4 mmol/

mol (0.3%); 95% CI: �0.49, �0.17; P < 0.0001; I2 = 64%], 18 months [n = 3 studies; MD = 8 mmol/mol (0.7%); 95%

CI: �1.26, �0.18; P = 0.009; I2 = 50%] and at 36– 48 months [n = 5 studies; MD = 10 mmol/mol (0.9%);

95% CI: �1.52, �0.34; P = 0.002; I2 = 93%]. By contrast, when eight studies comparing group-based interventions

with controls measured HbA1c at 24 months post baseline,

there was no significant difference between the groups. This

time point also had the highest heterogeneity (I2 = 94%).

There was variation in effectiveness in reducing FBG when

comparing group-based interventions with controls. Group-

based education was significantly more effective at reducing

FBG compared with controls at 12–14 months post baseline

(n = 8 studies; MD = 0.68 mmol/l; 95% CI: �1.25, �0.11;

P = 0.02; I2 = 55%). However, this was not the case for

FBG when measured at 6–10 or 24 months post baseline. All

time points were assessed as having significant heterogeneity.

Group-based education was significantly more effective at

reducing body weight compared with controls at both 6–