Appendices: Appendix Document A1: Search strategy for Medline (1960 November 2015) Appendix Table A1: Detailed Risk of Bias Table Appendix Figure A1: Funnel plot Appendix Figure A2: Sensitivity analysis excluding cluster randomized trials Appendix Figure A3: Subgroup analysis of studies by control intervention method Appendix Figure A4: Subgroup analysis of studies by method of peer support Appendix Figure A5: Subgroup analysis of studies by presence or absence of peer supervision Appendix Figure A6: Meta-regression plot of effect of peer training hours on effect size Appendix Figure A7: Meta-regression plot of effect of baseline Hemoglobin A1C on effect size Appendix Figure A8: Meta-regression plot of effect of duration of observation on effect size Appendix Document A1: Search strategy for Medline (1960 November 2015) 01. exp Diabetes Mellitus/ or diabetes.ti. 02. Hemoglobin A, Glycosylated/ or (HbA1c or A1c or glycated h?emoglobin* or glycosylated h?emoglobin* or glyc?emic control or clinical outcome*).mp. 03. Peer group/ or (peer*1 or peer health or peer support or peer led or peer educator* or peer coach* or peer counsel* or peer advis*).mp. 04. Patient Education as Topic/ or patient education.mp. 05. Self-Help Groups/ or self help group* 06. Social Support/ or (social support or promotora).mp.
07. 4 or 5 or 6 08. peer*1.mp. 09. 7 and 8 10. 1 and 2 and 3 and 9 11. limit 10 to yr= 1960-Current 12. randomized controlled trial.pt. or randomized controlled trials as topic/ or random*.ti,ab. 13. 11 and 12 Summary of Results Ovid Medline and Ovid Medline In Process 62 MASR 68 RCT Cochrane Central Register of Controlled Trials 62 RCT Cochrane Database of Systematic Reviews 37 MASR Scopus 16 MASR 44 RCT CINAHL Medline excluded 3 MASR 21 RCT PsycINFO 1 MASR
7 RCT ProQuest Dissertations & Theses A&I, BioOne Abstracts & Indexes, Social Service Abstracts, and 0 results Sociological Abstracts OCLC First Search 34 RCT Author searches of Scopus, CINAHL, PsycINFO and Google Scholar 45 citations Total 400 citations retrieved Minus 195 duplicates removed Leaves 205 unique citations
Appendix Table A1: Detailed Risk of Bias Table Study Name Adequate Sequence Generation Allocation Concealment Blinding of Participants, Personnel and Outcome Assessors Complete Outcome Data Keyserling 2002 Lorig 2008 Lorig 2009 Dale 2009 Cade 2009 Stratified block randomization with randomly permuted blocks of size 3 and 6 from random numbers generated by a personal computer Yes: Random-number tables a Yes: Randomization using random-number tables Yes: Randomization protocol mentioned Yes?: Participants were randomized into intervention or the control arm but no information on sequence generation available. Sealed envelopes No Yes: Dropout < 20%. Similar dropout in both groups. Follow-up data were analyzed according to group assignment Yes: Random-number tables for each allocation that were used randomly a Yes: Random-number tables for each allocation that were used randomly a No: Participants could not be blinded. No: Participants could not be blinded. Yes: Dropout < 20%. Attrition reported. The proportion of intervention non-completers compared with that of usual-care control non-completers was not statistically significant. Yes: Dropout < 20%. Attrition reported. Proportion of intervention non-completers compared to usualcare control non-completers was not significant. Yes: Dropout < 20%.Attrition Yes: Opaque sealed Not reported envelopes mentioned with some reasons. Not reported Not reported Yes: Dropout < 20% from baseline measurements Attrition mentioned Dropout between randomization and baseline measurements. At 12 months, clinical data (HbA1C) was available on 86 (77%) of the
Heisler 2010 Philis-Tsamakas 2011 Smith 2011 Long 2012 Yes: Random sequence generation and treatment group assignment were determined centrally just before the initial session. Yes: Blocked random assignment using a randomly generated numbers sequence Yes: Cluster randomization using minimization Yes: Using the randomnumber generator function, each group assignment given a random number and put the ordered numbers in envelopes Yes: Sequence was concealed until interventions were assigned. Yes: Patients, research staff, and care managers were blinded to randomization results until after the baseline surveys and physiologic measures were completed. Data assessors remained blinded to group assignment throughout the study. intervention participants and 118 (93%) control participants. Yes: Dropout < 20%. Attrition with reasons mentioned in flow diagram. Allocation concealment was done a No a Yes: Dropout > 20%Attrition mentioned with reasons of attrition. Fifty-one (25%) participants were lost to follow-up (Project Dulce group, n = 35 [33.5%]; control group, n = 16 [15.5%]); however, at baseline, these participants did not differ significantly from those who completed at least one follow-up assessment on any demographic or outcome variable (p = 0.05). Yes a : Allocation carried out independently of the research team Minimization was undertaken by an independent statistician Yes: Envelopes were sealed, shuffled, and stacked, and the research assistant took the top envelope after consent was obtained to determine group assignment. No Yes: Study investigators were blinded to allocation and results until study completion. Yes: 15% dropout Attrition with reasons mentioned. Yes: Dropout < 20% Attrition mentioned in flow diagram with some reasons.
Gagliardino 2013 Siminerio 2013 Thom 2013 Chan 2014 Simmons 2014 Safford 2015 Ayala 2015 McGowan 2015 Yes?: Random assignment mentioned in Methods but no information received on sequence generation Yes: Randomization was done by a computer program a Yes: Assigned to usual care or peer-coaching study arm using randomly ordered opaque envelopes. Yes: Computer-generated, block randomization 1:1 assignment. Yes: Clusters were randomized in blocks of four Yes: Random-number generator. Yes: Conducted by study biostatistician and stratified by clinic. Yes: Block randomization, for each block randomnumber generator used Not reported Not reported Attrition unclear No a No a Yes: Dropout < 20% Attrition with reasons mentioned. Yes: Opaque envelopes. Yes: Opaque envelop opened by non-nursing staff not involved in research. Yes: Randomization by statistician who had no trial involvement after all clusters enrolled Yes: Randomization at the cluster level predated participant recruitment and was secure. No a Not reported Yes: Outcomes assessors and investigators were masked to arm allocation. No: Participants and peer coaches were not blinded. Yes: Dropout < 20%.Attrition mentioned. Yes: Dropout < 20% Attrition with reasons mentioned. Yes: 23.9% dropout. Attrition mentioned. Dropout < 20% Attrition mentioned.?no: Not reported Not reported 27% dropout Attrition with reasons mentioned. Yes: Anonymized study identification numbers were assigned to each subject. No: Participants were not blinded. 34% dropout Attrition with reasons mentioned. Yes indicates low risk of bias; Yes? Likely low risk of bias but no details on sequence generation available from article and author; No indicates high risk of bias;?no is not reported or no response from author. a author response to email requests Selective outcome reporting risk was considered minimal since we only selected studies which reported hemoglobin A1C as the outcome. There were no significant other biases noted in the included studies.
Appendix Figure A1: Funnel plot Funnel Plot of Standard Error by Std diff in means 0.0 0.1 Standard Error 0.2 0.3 0.4-2.0-1.5-1.0-0.5 0.0 0.5 1.0 1.5 2.0 Std diff in means
Appendix Figure A2: Sensitivity analysis excluding cluster randomized trials Study name Statistics for each study Std diff in means and 95% CI Std diff Lower Upper in means limit limit p-value Keyserling 0.029-0.311 0.369 0.866 Lorig 2008 0.240 0.047 0.433 0.015 Lorig 2009-0.067-0.279 0.144 0.534 Dale -0.306-0.594-0.017 0.038 Cade -0.159-0.435 0.117 0.258 Heisler 0.377 0.124 0.630 0.004 Philis-Tsimakas 0.371 0.097 0.646 0.008 Long 0.661 0.202 1.120 0.005 Gagliardino 0.000-0.279 0.279 1.000 Siminerio 0.108-0.369 0.584 0.658 Thom 0.357 0.129 0.586 0.002 Chan 0.007-0.150 0.163 0.934 Ayala 0.205-0.009 0.419 0.061 McGowan 0.248 0.029 0.467 0.027 Pooled SMD 0.137 0.021 0.254 0.021 I 2 of 66.030% p for heterogeneity <0.001-1.00-0.50 0.00 0.50 1.00 Favors control Favors peer support
Supplement efigure 3: Subgroup analysis of studies by control intervention method Appendix Figure A3: Subgroup analysis of studies by control intervention method Group by control intervention Study name Statistics for each study Std diff in means and 95% CI Std diff Lower Upper in means limit limit p-value Education or Nurse care Keyserling 0.029-0.311 0.369 0.866 Education or Nurse care Gagliardino 0.000-0.279 0.279 1.000 Education or Nurse care Siminerio 0.108-0.369 0.584 0.658 Education or Nurse care Chan 0.007-0.150 0.163 0.934 Education or Nurse care Safford 0.181-0.104 0.465 0.213 Education or Nurse care pooled effect 0.041-0.072 0.153 0.477 Usual care Lorig 2008 0.240 0.047 0.433 0.015 Usual care Lorig 2009-0.067-0.279 0.144 0.534 Usual care Dale -0.306-0.594-0.017 0.038 Usual care Cade -0.159-0.435 0.117 0.258 Usual care Heisler 0.377 0.124 0.630 0.004 Usual care Philis-Tsimakas 0.371 0.097 0.646 0.008 Usual care Smith 0.000-0.208 0.208 1.000 Usual care Long 0.661 0.202 1.120 0.005 Usual care Thom 0.357 0.129 0.586 0.002 Usual care Simmons 0.029-0.153 0.211 0.753 Usual care Ayala 0.205-0.009 0.419 0.061 Usual care McGowan 0.248 0.029 0.467 0.027 Usual care pooled effect 0.147 0.021 0.273 0.023 Group education or nurse care management control intervention: I 2 = 0.00, p for heterogeneity 0.86 Usual care: I 2 = 70.53%, p for heterogeneity<0.001-1.00-0.50 0.00 0.50 1.00 Favors control Favors peer support
Supplement Supplement Figure efigure A4: 4: Subgroup analysis of of studies studies by method by method of peer of support peer support Group by peer intervention method Study name Statistics for each study Std diff in means and 95% CI Std diff Lower Upper in means limit limit p-value group education Lorig 2008 0.240 0.047 0.433 0.015 group education Lorig 2009-0.067-0.279 0.144 0.534 group education Cade -0.159-0.435 0.117 0.258 group education Philis-Tsimakas0.371 0.097 0.646 0.008 group education Smith 0.000-0.208 0.208 1.000 group education McGowan 0.248 0.029 0.467 0.027 group education pooled effect 0.106-0.050 0.262 0.182 group+telephone Keyserling 0.029-0.311 0.369 0.866 group+telephone Gagliardino 0.000-0.279 0.279 1.000 group+telephone Simmons 0.029-0.153 0.211 0.753 group+telephone Ayala 0.205-0.009 0.419 0.061 Group + telephone pooled effect 0.076-0.040 0.193 0.201 Telephone Dale -0.306-0.594-0.017 0.038 Telephone Heisler 0.377 0.124 0.630 0.004 Telephone Long 0.661 0.202 1.120 0.005 Telephone Siminerio 0.108-0.369 0.584 0.658 Telephone Thom 0.357 0.129 0.586 0.002 Telephone Chan 0.007-0.150 0.163 0.934 Telephone Safford 0.181-0.104 0.465 0.213 Telephone pooled effect 0.179-0.028 0.386 0.091-1.00-0.50 0.00 0.50 1.00 Group education: I 2 64.67%, p for heterogeneity 0.01 Group education + telephone support: I 2 0.00%, p for heterogeneity 0.57 Telephone: I 2 74.83%, p for heterogeneity 0.001 Favors control Favors peer support
Supplement efigure 5: Subgroup analysis of studies by presence or absence of peer supervision Appendix Figure A5: Subgroup analysis of studies by presence or absence of peer supervision Group by peer supervision Study name Statistics for each study Std diff in means and 95% CI Std diff Lower Upper in means limit limit p-value No supervision Keyserling 0.029-0.311 0.369 0.866 No supervision Dale -0.306-0.594-0.017 0.038 No supervision Cade -0.159-0.435 0.117 0.258 No supervision Long 0.661 0.202 1.120 0.005 No supervision Thom 0.357 0.129 0.586 0.002 No supervision Simmons 0.029-0.153 0.211 0.753 No supervision pooled effect 0.078-0.157 0.313 0.515 Supervised Peers Lorig 2008 0.240 0.047 0.433 0.015 Supervised Peers Lorig 2009-0.067-0.279 0.144 0.534 Supervised Peers Heisler 0.377 0.124 0.630 0.004 Supervised Peers Philis-Tsimakas 0.371 0.097 0.646 0.008 Supervised Peers Smith 0.000-0.208 0.208 1.000 Supervised Peers Gagliardino 0.000-0.279 0.279 1.000 Supervised Peers Siminerio 0.108-0.369 0.584 0.658 Supervised Peers Chan 0.007-0.150 0.163 0.934 Supervised Peers Safford 0.181-0.104 0.465 0.213 Supervised Peers Ayala 0.205-0.009 0.419 0.061 Supervised Peers McGowan 0.248 0.029 0.467 0.027 Supervised Peers pooled effect 0.143 0.050 0.237 0.003 No supervision: I 2 77.09%, p for heterogeneity 0.001 No supervision: I 2 77.09%, p for heterogeneity 0.001 Supervised peers: I 2 43.24%, p for heterogeneity 0.06-1.00-0.50 0.00 0.50 1.00 Supervised peers: I 2 43.24%, p for heterogeneity 0.06 Favors control Favors peer support
Appendix Figure A6: Meta-regression plot of effect of peer training hours on effect size Regression of Std diff in means on Peer training hours 0.80 0.60 0.40 Std diff in means 0.20 0.00-0.20-0.40 Slope: 0.001 p = 0.8-0.60-0.80-20.0-10.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 Peer training hours
Appendix Figure A7: Meta-regression plot of effect of baseline Hemoglobin A1C on effect size Regression of Std diff in means on baseline a1c 1.00 0.80 0.60 0.40 Std diff in means 0.20 0.00-0.20-0.40 Slope 0.0657 P = 0.09-0.60-0.80 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 baseline a1c
Appendix Figure A8: Meta-regression plot of effect of duration of observation on effect size Regression of Std diff in means on Months of observation after intervention completed 0.80 0.60 0.40 Std diff in means 0.20 0.00-0.20-0.40 Slope -0.004-0.60 P = 0.8-0.80 0.0 2.0 4.0 6.0 8.0 10.0 12.0 Months of observation after intervention completed