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Table 2 Evidence synthesis on differential effect analyses by PROGRESS-Plus factors

From: Quality improvement strategies at primary care level to reduce inequalities in diabetes care: an equity-oriented systematic review

Study, country PROGRESS-factor Intervention type Outcome Method of analysis Overall intervention effect Differential effect
Anderson 2010 [61]
Spanish speaking only, education level Patient level
Number of experimental conditions:
2 (1 intervention, 1 control)
• telephonic disease management (weekly, bi-weekly, or monthly) based on:
1. brief clinical assessment
2. self-management: including diet, exercise, stress reduction,
smoking cessation, readiness assessment, and development
of specific self-management goals
3. medication adherence
4. glucose monitoring and review of home glucose monitoring results
• educational materials
Personnel involved: nurse
Control group:
• Usual care at Community Health Center
A1c, DBP,SBP, BMI, LDL, diet behavior (BDA); physical activity (RAPA); depression measured Patient Health questionnaire (PHQ-9) Subroups analysis and interaction analysis No significant differences between groups for any outcomes
Retention rate
79% vs 64%
Spanish speakers (yes vs no)
MD = − 0.10(− 0.53, 0.33) vs 0.35(− 0.17, 0.88)
Educational level:
(high level vs low level)
MD = 0.14(− 0.30, 0.57) vs 0.00(− 0.52, 0.52)
None of the interactions was significant
Anderson-Loftin 2005 [37]
Gender Patient level
Number of experimental conditions:
2 (1 intervention, 1 control)
• Education in low fat dietary strategies (4 weekly classes)
• 1-h peer-professional discussion groups (5 monthly)
• Additional educational support by phone (weekly)
• Incentives for attendance
Personnel involved: nurse case manager
Control group:
• Usual care including a referral to a local 8-h traditional diabetes class (information on nature and complications of diabetes)
• Incentives for attendance
A1c, BMI, LDL, weight, dietary fat behaviors assessed by FHQ, physical activity, psychological status Stratification by gender A1c
No significant differences
Mean weight
Significant effect
I: - 4 lb.
C: + 4.2 lb.
I: − 0.81 kg/mm2
C: +  0.57 kg/mm2
MD = 1.38 kg/mm2
p = 0.009
Dietary behaviors (FHQ score)
I: 2.5 ± 0.4
C: 2.6 ± 0.4
MD = 0.2
p = 0.005
Men vs women
No significant differences
Mean weight
Significant effect
+ 5.4 lb. vs − 1.5 lb.;
MD = 6.9 lb.
+ 2 kg/mm2 vs 0.16 kg/mm2
p = 0.02
Dietary behaviors
Significant effect
(FHQ score)
− 0.24 vs − 0.17
Babamoto 2009 [58]
Age Healthcare level
Number of experimental conditions: 3 (2 intervention, 1 control)
• Group A, CHW program, Amigos en Salud (Friends in Health): education through individual session and monitoring services; individual sessions with participants and family member; telephone calls to participants to monitor self-management, to help participants improve their diabetes self-management skills
• Group B, case management: education from two linguistically competent and culturally sensitive. Patients case management were usually seen on a monthly basis + follow-up calls.
Personnel involved: bilingual, trained community health workers, nurse case manager
Setting: Community, home, clinic
Control group
Standard Provider Care: standardized clinical care by physicians and nurse practitioners, without case management or CHW services
BMI, A1C, medication adherence, diet, physical activity, emergency department admission (ED) Logistic regression models Mean A1c
Within group
CHW = 8.6 to 7.2%; p < 0.05
CM =8.5 to 7.4%; p < 0.05
Standard care = 9.5 to 7.4%;p < 0.05
No significant differences were found between groups
BMI Significantly greater decrease for the CHW group compared with the standard care group OR = 2.9 (95% CI 1.1–6.6)
Change from baseline CHW: total visit decrease 11%
Case management: total visit increase 40% Standard care: increase 15%
between groups at 6-month follow-up p < 0.05
CHW group were more likely (OR = 2.43; 95% CI =1.13–5.23) to report having two or more servings of fresh fruit per day than standard care
Physical activity
CHW group was more likely (OR = 2.87, 95% CI = 1.34–6.17) than standard care to report exercising three or more times per week
Patients aged≥50 were less likely to have reduced BMI at follow-up
ORa = 0.4 (95% CI = 0.2–0.8)
Exercise frequencyb 3 times or more per week vs 2 times or fewer per week
OR = 2.2 (95% CI = 1.1–4.1)
Brown, 2011 [63]
Gender Patient level
Number of experimental conditions: 2 (1 intervention, 1 control)
• Diabetes self-management education (DSME) including 8 consecutive weeks of education followed by a support group session at 3 and 6 months
• Experienced NCM providing: culturally tailored diabetes self-management education; individualized health guidance and assistance with overcoming cultural and environmental barriers to improving health; guidance on locating, accessing, and navigating healthcare services; enhanced coordination of health care and communication with physicians and other healthcare providers
• Random observations visits
Personnel involved: bilingual NCM, nurses, dietitians, and CHWs
Control Group: DSME intervention only
A1c, FBG, lipids, BP, BMI, diabetes-related knowledge, health behaviors (physical activity, dietary intake, glucose monitoring) Interaction terms in hierarchical linear and nonlinear models to test for differential impact of treatment by gender Over time, both the experimental and control groups showed improvements in FBG levels at three and
At six months
For A1c the control group had greater clinical improvements at both intervals
Self-reported physical activity and fat intake
Improvement for both experimental and control groups
No significant differences between gender
The rate of change in A1c over time did not differ significantly by gender (coefficient^ = − 0.06, t ratio = 0.25, p = 0.806)
Forjuoh 2014 [64]
Race/ethnicity Patient level
Number of experimental conditions: 4 (3 intervention, 1 control)
• Group A. self-management through personal digit assistant (PDA). Diabetes Pilot Chronic Disease Self Management Program (CDSMP): 6 week group education program to increase self efficacy
• Group B. self-management through PDA
• Group C. combination of A + B
Personnel involved: trained facilitator, project coordinators
Setting: outpatient clinic, community
Control group: usual clinical diabetes care, along with patient education materials
A1C, physical activity, BMI, BP, diet Interaction terms in multilevel models to test for differential impact of treatment by race/ethnicity BMI and BP: Modest reductions from baseline to 12 months of follow-up for all four groups.
No significant difference for other outcomes.
Self care activities:
Hispanic washing feet significantly more than other racial/ethnic groups (P = 0.02)
Retention rate:
CDSMP: 85%; PDA 64%, CDSMP + PDA 64%; Control 78%
Modest reductions occurred in A1c from baseline to 12 months of follow-up for all/ethnic groups.
There was no significant difference in A1c change over time by race/ethnicity.
Gerber 2005 [36]
Health literacy Patient level
Number of experimental conditions:
2 (1 intervention, 1 control)
Education by computer multi-media including audio/video sequences (“Living Well with Diabetes”) to communicate information, provide psychosocial support and promote self-management. Subject received compensation based on computer usage. Lessons in English and Spanish. Navigation provided through a simplified interface, including forward/backward buttons for user control. Advanced features included “pop-up” supplementary text information or additional testimonials related to the concurrent screen concept
Personnel involved: bilingual research assistant
Setting: urban outpatient clinics
Control group: simple multiple-choice quizzes on diabetes-related concepts
A1c, BMI, BP, eye exam, diabetes knowledge, self-efficacy, self-reported medical care, and perceived susceptibility to complications Stratification by level of health literacy No significant differences for all outcomes but perceived susceptibility to diabetes complications Lower literacy group
% change A1c
− 0.21 ± 2.0 vs − 0.1% ± 1.3
MD = − 0.10 [− 0.67, 0.47]
People with A1c > 9%
− 2.1 vs − 0.3 (p = 0.036)
Perceived susceptibility to complications
% change score=
1.48 ± 2.7 vs 0.19 ± 2.5 (p = 0.016)
trend toward greater improvement in self-efficacy
1.51 ± 1.5 vs. 0.99 ± 1.4
(p = 0.113)
Higher literacy
% change A1c
+ 0.3% ± 1.6 vs. -0.5 ± 1.5
MD = 0.80 [0.22, 1.38]
Perceived susceptibility to complications
0.76 ± 2.5 vs. 0.29 ± 2.4 (p = 0.267)
Medical care Improvement over time (p < 0.012 for time interaction)
but no effect for either lower- or higher-literacy groups
Sixta 2008 [28]
age Healthcare level
Number of experimental conditions: 2 (1 intervention, 1 control)
Diabetes culturally self-management education with group sessions
Personnel involved: promotores in consultation with a care team
Control group:Usual care delivered by provider at the clinic or to a self-care management
A1C, knowledge, beliefs Stratified analysis by age A1C, knowledge, beliefs A1C
No difference between groups
No difference between groups
DKQ, HBQ, and HbA1c results were significantly affected by age;
Slightly negative effect on DKQ scores per year of age.
Slightly negative effect on HBQ scores and HbA1c levels per year of age
West 2007 [70]
Race/ethnicity Patient level
Number of experimental conditions:
2 (1 intervention, 1 control)
• 42 group session of behavioral weight control program focusing on attainable and sustainable changes in dietary and physical activity habits
• Motivational interviewing: 5 individual sessions lasted 45 min
Personnel involved: Behaviorist, nutritionist, diabetes educator, trained clinical psychologist
Setting: outpatient clinic
Control group: health education sessions with focus on women’s health topics
A1C, glucose monitoring The weight patterns over time by race were examined using a two-factor repeated measures ANOVA stratified by treatment Weight
At 6 months
Means: − 4.7 ± 5.4 kg vs − 3.1 ± 3.9 kg (p = 0.03)
Over 18 months:
Means: − 3.5 ± 6.8 Kg vs − 1.7 ± 5.7Kg (p = 0.04)
Decrease in both groups (p < 0.0001) at 6 months but not sustained at 18 months
Greater decrease in the intervention than in the control group (p = 0.002)
Weight at 6 months regardless treatment:
African-American vs White
-3 kg ± 3.9 vs. -4.5 ± 5.1 kg (p = 0.03)
Weight at 12 months regardless treatment::
− 2.3 kg ± 4.4 vs − 4.6 ± 6.8 kg (p = 0.09)
Weight at 18 months regardless treatment:
− 1.4 kg ± 4.7 vs − 3.3 ± 7.1 kg (p = 0.09)
For African-American experimental intervention produced greater weight loss than control group at 3 and 6 months. The benefit was not sustained after 12 months
African American had high A1c values regardless of treatment assignment. No interaction by race Attendance between groups was comparable.
  1. Data are means ± SD; I intervention group, C control group, OR odds ratio, A1c, Glycated hemoglobin; BMI Body Mass Index, LDL low density cholesterol, BP blood pressure, SBP systolic blood pressure, DBP diastolic blood pressure, MD mean difference, FHQ food habit questionnaire, PHQ-9 Patient Health Questionnaire, DSME Diabetes self-management education, DKQ diabetes knowledge questionnaire, HBQ Health Beliefs Questionnaire
  2. amultivariate analysis adjusted for study group, gender, dietary, exercise activity; bunivariate analysis (did not persist after the other covariates were controlled for); ^b = regression coefficient