Table 3.

Characteristics related to external validity for trials in PRECIS-2 bottom two tertiles

First author, year, location	Participants (n), age, females (%), non-white (%), HbA1c (mean)	Clinical setting	Intervention duration, intervention frequency, follow-up
Middle tertile
Babamoto (CHW) et al., 2009, USAa	I: n = 75, 51 yr., 64% f, NR n-w, A1c—8.6% C: n = 54, 50 yr., 78% f, NR n-w, A1c—9.5%	3 inner city family health centers in Los Angeles, CA	Duration: 6 mo. Frequency: 11.3 sessions (in person and telephone contact) Follow-up: 6 mo.
De Greef (Group) et al., 2011, Belgiuma	I: n = 21, 70.0 yr., 38.1% f, NR n-w, A1c—7.12% C: n = 24, 66.0 yr., 29.2% f, NR n-w, A1c—7.00%	Three Belgian general practices	Duration: 12 wks. Frequency: three 90-min group counseling sessions Follow-up: 12 wks.
Van der Weegen (SSP w/ tool) et al., 2015, Netherlands	I: n = 65, 57.5 yr., 52.3% f, NR n-w, A1c—NR C: n = 68, 59.2 yr., 54.4% f, NR n-w, A1c—NR	24 general practices in the south of the Netherlands	Duration: 6 mo. Frequency: 4 consultations with practice nurse occurring during first wk., after 2 wks., after 8–12 wks., and after 16–24 wks. Follow-up: measured at baseline after the intervention (4–6 mo.), and 3 mo. thereafter
Keyserling (Group B) et al., 2002, USA	I: n = 66, 59.8 yr., 100% f, 100% n-w, A1c—11.1% C: n = 67, 59.2 yr., 100% f, 100% n-w, A1c—11.3%	Primary care practices in central NC (5 community health centers, 1 staff model health maintenance organization, 1 general medicine clinic at an academic health center)	Duration: 6 mo. Frequency: 4 monthly visits Follow-up: 12 mo.
Van der Weegen (SSP) et al., 2015, Netherlandsa	I: n = 66, 56.9 yr., 47.0% f, NR n-w, A1c—NR C: n = 68, 59.2 yr., 54.4% f, NR n-w, A1c—NR	24 general practices in the south of the Netherlands	Duration: 6 mo. Frequency: 4 consultations with practice nurse occurring during first wk., after 2 wks., after 8–12 wks., and after 16–24 wks. Follow-up: measured at baseline after the intervention (4–6 mo.), and 3 mo. thereafter
Edelman et al., 2015, USA	I: n = 193, 57.8 yr., 54.4% f, 50.8% n-w, A1c—9.2% C: n = 184, 59.6 yr., 54.9% f, 49.5% n-w, A1c—9.0%	9 primary care practices in the Duke Clinical Research Institute Primary Care Research Consortium	Duration: 2 yrs. Frequency: phone calls every 2 mo. (12 total) Follow-up: 2 yrs.
Naik et al., 2011, USA	I: n = 45, 63.82 yr., NR f, 33.3% n-w, A1c—8.86% C: n = 42, 63.45 yr., NR f, 28.6% n-w, A1c—8.74%	Michael E. DeBakey Veterans Affairs Medical Center in Houston, Texas	Duration: 3 mo. Frequency: 4 group sessions every 3 wks. Follow-up: 3 mo.
Glasgow (CASM+) et al., 2012, USAa	I: n = 162, 58.7 yr., 53.7% f, 29.3% n-w, A1c—NR C: n = 132, 58.7 yr., 51.5% f, 29.4% n-w, A1c—8.16%	Five primary care clinics within Kaiser Permanente Colorado	Duration: 12 mo. Frequency: three 120-min group sessions after week 6; follow-up telephone calls at wks. 2 and 8; periodic motivational calls Follow-up: 12 mo.
Francosi et al., 2011, Italy	I: n = 46, 48.9 yr., 30.4% f, NR n-w, A1c—7.9% C: n = 16, 48.7 yr., 12.5% f, NR n-w, A1c—7.9%	3 OP diabetes clinics	Duration: 6 mo. Frequency: Face-to-face encounter every 3 mo. with diabetes nurses and additional telephone contact monthly Follow-up: 6 mo.
Maindal et al., 2014, UK	I: n = 322, 62.0 yr., 47.2% f, NR n-w, A1c—6.3% C: n = 187, 62.0 yr., 46.0% f, NR n-w, A1c—6.2%	33 general practices in a large Danish county	Duration: 3 mo. Frequency: 2 individual counseling interviews and 8 group sessions, totaling 18 h. Follow-up: 3 yrs.
Jarab et al., 2012, Jordan	I: n = 85, 63.4 yr., 42.4% f, NR n-w, A1c—8.5% C: n = 86, 65.3 yr., 44.2% f, NR n-w, A1c—8.4%	OP diabetes clinic at the 762-bed Royal Medical Services Hospital	Duration: 8 wks. Frequency: baseline face-to-face objective directed education and weekly telephone follow-up calls Follow-up: 6 mo.
Schillinger (ATSM) et al., 2009, USA	I: n = 112, 55.9 yr., 58.0% f, 87.5% n-w, A1c—9.3% C: n = 114, 55.8 yr., 55.3% f, 93.8% n-w, A1c—9.8%	9 clinics in the San Francisco Department of Public Health’s Community Health Network (CHNSF)	Duration: 9 mo. Frequency: weekly automated phone calls w/ follow-up calls from care manager if necessary Follow-up: 1 yr.
Trento et al., 2008, Italy	I: n = 25, 64.6 yr., 48.0% f, NR n-w, A1c—8.0% C: n = 24. 68.1 yr., 33.3% f, NR n-w, A1c—8.0%	Department of Internal Medicine, University of Turin	Duration: 2 yrs. Frequency: 40–50 min. Group sessions very 3–4 mo. Follow-up: 2 yrs.
Trento et al., 2002, Italy	I: n = 56, 62.0 yr., 51.8% f, NR n-w, A1c—7.4%’ C: n = 56, 61.0 yr., 39.3% f, NR n-w, A1c—7.4%	Diabetes clinic, Department of Internal Medicine, University of Turin	Duration: 4 yrs. Frequency: group educational sessions once every 3 mo. for 2 yrs.; 7 sessions spread over yrs. 3–4 Follow-up: 4 yrs.
Barratt et al., 2008, UK	I: n = 27, NR yr., NR f, NR n-w, A1c—9.6% C: n = 26, NR yr., NR f, NR n-w, A1c—9.7%	Two tertiary hospitals in southeast England	Duration: 6 mo. Frequency: one 90-min. session and five 30-min. sessions Follow-up: 6 mo.
Bottom tertile
Kim (PM) et al., 2006, South Korea	I: n = 22, NR yr., NR f, NR n-w, A1c—7.51% C: n = 23, NR yr., NR f, NR n-w, A1c—7.87%	OP diabetes clinic at a large university hospital in South Korea	Duration: 12 wks. Frequency: 2× in first 2 wks., again at 6 wks. Follow-up: 12 wks.
Kim (WB) et al., 2006, South Koreaa	I: n = 28, NR yr., NR f, NR n-w, A1c—7.99% C: n = 23, NR yr., NR f, NR n-w, A1c—7.87%	OP diabetes clinic at a large university hospital in South Korea	Duration: 12 wks. Frequency: 2× in first 2 wks., again at 6 wks. Follow-up: 12 wks.
Keyserling (Group A) et al., 2002, USAa	I: n = 67, 58.5 yr., 100% f, 100% n-w, A1c—10.8% C: n = 67, 59.2 yr., 100% f, 100% n-w, A1c—11.3%	Primary care practices in central NC (5 community health centers, 1 staff model health maintenance organization, 1 general medicine clinic at an academic health center)	Duration: 12 mo. Frequency: 4 monthly visits, 3 group sessions, and 4 monthly phone calls Follow-up: 12 mo.
Schillinger (GMV) et al., 2009, USAa	I: n = 113, 56.5 yr., 63.7% f, 91.1% n-w, A1c—9.4% C: n = 114, 55.8 yr., 55.3% f, 93.8% n-w, A1c—9.8%	9 clinics in the San Francisco Department of Public Health’s Community Health Network (CHNSF)	Duration: 9 mo. Frequency: monthly group meetings (90 min. each) Follow-up: 1 yr.
Anderson et al., 2010, USA	I: n = 146, NR yr., 58.9% f, 72.6% n-w, A1c—7.6% C: n = 149, NR yr., 57.1% f, 73.8% n-w, A1c—8.4%	2 largest Community Health Center, Inc. locations in CT	Duration: 1 yr. Frequency: weekly/bi-weekly/monthly (depending on risk stratification) Follow-up: 1 yr.
Lim et al., 2015, South Korea	I: n = 50, 64.3 yr., 20% f, NR n-w, A1c—8.1% C: n = 50, 65.8 yr., 30% f, NR n-w, A1c—7.9%	OP clinic, Bundang Hospital, Seoul National University	Duration: 6 mo. Frequency: 1-h diet and exercise counseling at baseline, 3, and 6-month visits Follow-up: 6 mo.
Thoolen et al., 2009, Netherlands	I: n = 78, 62.0 yr., 36.0% f, NR n-w, A1c—NR C: n = 102, 61.9 yr., 45.0% f, NR n-w, A1c—NR	General practices in southwest Netherlands	Duration: 12 wks. Frequency: two individual and four group sessions (2 h./session) with nurse Follow-up: 3 and 12 mo.
Taylor et al., 2003, USA	I: n = 84, 55.5 yr., 50% f, 33.3% n-w, A1c—9.5% C: n = 85, 54.8 yr., 44.7% f, 43.5% n-w, A1c—9.5%	Kaiser Permanente Medical Center in Santa Clara, CA	Duration: 1 yr. Frequency: 90 min. RN consultation; weekly 1- to 2-h group classes for 4 wks; telephone follow-up before 4th group session and at wks. 5, 8, 12, 16, 20, 28, 36, and 44 (∼15 mins./call) Follow-up: 1 yr.
Moriyama et al., 2009, Japan	I: n = 42, 66.4 yr., 59.5% f, NR n-w, A1c—7.5% C: n = 23, 65.2 yr., 43.5% f, NR n-w, A1c—7.4%	2 hospitals with less than 200 beds in a Japanese city	Duration: 1 yr. Frequency: monthly ∼30-min. sessions; phone calls from nurse educator every 2 wks. Follow-up: 1 yr.
Van Dyck et al., 2011, Belgium	I: n = 60, 62.37 yr., NR f, NR n-w, A1c—NR C: n = 32, 60.59 yr., NR f, NR n-w, A1c—NR	Endocrinology Department of the Ghent University Hospital	Duration: 24 wks. Frequency: face-to-face 30-min. session with psychologist; phone call every 2 wks. For first month, every 4 wks. For next 20 wks. (7 calls, ∼20 mins. each) Follow-up: 1 yr.
Kim et al., 2011, South Korea	I: n = 21, 56.62 yr., 47.6% f, 100% n-w, A1c—7.40% C: n = 22, 54.68 yr., 31.8% f, 100% n-w, A1c—7.41%	OP diabetic center at a large university hospital in South Korea	Duration: 16 wks. Frequency: 60–90-min. initial counseling session; 30–40-min. follow-up counseling session every 2 mo; 10–30-min. weekly telephone calls Follow-up: 16 wks.
Sone et al., 2010, Japan	I: n = 1017, 58.5 yr., 46.0% f, NR n-w, A1c—7.8% C: n = 1016, 58.6 yr., 47.0% f, NR n-w, A1c—7.9%	59 university and general hospitals that specialize in diabetes care	Duration: 8 yrs. Frequency: 15-min. telephone counseling sessions at least once every 2 wks; 5–10-min. extra during each clinic visit Follow-up: 7.8 yrs.
Uusitupa et al., 1996, Finland	I: n = 38, NR yr., 44.7% f, NR n-w, A1c—8.4% C: n = 40, NR yr., 40.0% f, NR n-w, A1c—9.0%	OP clinic of Department of Medicine, Kuopio University Hospital	Duration: 1 yr. Frequency: six visits to OP clinic at 2-mo. intervals Follow-up: 1 yr.
Gaede et al., 1999, Denmark	I: n = 80, 54.9 yr., 21.3% f, NR n-w, A1c—8.4% C: n = 80, 55.2 yr., 30.0% f, NR n-w, A1c—8.8%	Steno Diabetes Center	Duration: approximately 4–5 yrs., or when study endpoint was reached Frequency: every 3-mo. follow-up: At 2 and 4 yrs.
Huffman et al., 2010, USA	I: n = 38, NR yr., 0% f, NR n-w, A1c—NR C: n = 46, NR yr., 0% f, NR n-w, A1c—NR	Durham Veterans Affairs Medical Center in NC	Duration: 1 yr. Frequency: baseline counseling session; 3 biweekly phone calls over first 6 wks., monthly phone calls for study duration Follow-up: 1 yr.
First author, year, location	Intervention staff type, level of training	PA tracking method/feedback provided	eHealth
Middle tertile
Babamoto (CHW) et al., 2009, USAa	CHWs	N/A	N/A
De Greef (Group) et al., 2011, Belgiuma	Clinical psychologist with a background in behavior change strategies	Pedometers used to track progress and to encourage discussions with the behavioral expert	N/A
Van der Weegen (SSP w/ tool) et al., 2015, Netherlands	Practice nurse trained in delivery of the intervention	Participants used activity monitors to track activity on mobile phone and web app. Personal activity goals set based on dialog sessions and activity results	It’s LiFe! monitoring and feedback tool consisting of a three-dimensional activity monitor, a mobile phone app, and a web app
Keyserling (Group B) et al., 2002, USA	Nutritionists	N/A	N/A
Van der Weegen (SSP) et al., 2015, Netherlandsa	Practice nurse trained in delivery of the intervention	Participants recorded PA in diaries. They discussed their progress and made individual goals during sessions with practice nurses.	N/A
Edelman et al., 2015, USA	RN with extensive experience in case management	N/A	N/A
Naik et al., 2011, USA	PCPs trained in goal setting and action planning methodology	Participants received feedback on specific goals during one-on-one sessions with PCP	N/A
Glasgow (CASM+) et al., 2012, USAa	“Research project staff member,” diabetes care coordinator, nutritionist, bilingual family MD	Participants recorded progress on daily goals and received feedback using website. Patients also received follow-up calls at 2 and 8 weeks to discuss the their action plans	“My Path to Healthy Life” (Mi Camino a La Vida Sana) website
Francosi et al., 2011, Italy	Diabetes RNs trained in diabetes care during a 1-day session	Feedback provided during monthly phone calls	N/A
Maindal et al., 2014, UK	RNs, RDs, physiotherapists, and GPs who received formal training in autonomy support, participant-centered communication and action plan support	N/A	N/A
Jarab et al., 2012, Jordan	MDs and pharmacists	N/A	N/A
Schillinger (ATSM) et al., 2009, USA	Nurse care manager	Participant responses to automated phone calls triggered automated health education messages and/or nurse phone follow-up	N/A
Trento et al., 2008, Italy	RD and RNs trained in management of T2D	N/A	N/A
Trento et al., 2002, Italy	MDs and an educationist	N/A	N/A
Barratt et al., 2008, UK	RDs	Progress on personal goals discussed at each appointment	N/A
Bottom tertile
Kim (PM) et al., 2006, South Korea	Research RNs	PA frequency, intensity, and duration monitored weekly by diaries and kcal-pedometer. Research nurses provided feedback at clinic visits or with phone calls	N/A
Kim (WB) et al., 2006, South Koreaa	Research RNs	PA frequency, intensity, and duration monitored weekly by diaries and kcal-pedometer. Research nurses provided feedback at clinic visits or with phone calls. Web-based psychological and physical readiness questionnaires used to assess current stages of PA	Web site included stage-based personalized sections on goal setting, activity planning, determining target heart rates, and questionnaires
Keyserling (Group A) et al., 2002, USAa	Community diabetes advisors and nutritionists	N/A	N/A
Schillinger (GMV) et al., 2009, USAa	PCP and health educator	N/A	N/A
Anderson et al., 2010, USA	RNs trained in intervention delivery	N/A	N/A
Lim et al., 2015, South Korea	RD, exercise specialist, exercise physiologist	PA monitor results linked to the main server to provide tailored service	Dedicated website containing a glucose control section, diet control section, physical activity section, and an integrated widget. PA monitors and glucometers linked with the u-healthcare system
Thoolen et al., 2009, Netherlands	RN	N/A	N/A
Taylor et al., 2003, USA	RN	N/A	N/A
Moriyama et al., 2009, Japan	Nurse educators	Nurse educators contacted participants every 2 weeks to monitor exercise goals	N/A
Van Dyck et al., 2011, Belgium	Psychologists	Participants asked to keep a pedometer diary to track progress and encourage discussion with psychologist	N/A
Kim et al., 2011, South Korea	RN/MD Researchers	Weekly exercise and dietary logs indicated frequency, duration, and kilocalories for energy expenditure by an accelerometer	N/A
Sone et al., 2010, Japan	MDs, RNs, RDs, psychotherapists, and other co-medical staff	Pedometers used for objective assessment of PA	N/A
Uusitupa et al., 1996, Finland	MDs, RNs, and nutritionists	PA monitored by daily activity records	N/A
Gaede et al., 1999, Denmark	MD, RN, and RD	N/A	N/A
Huffman et al., 2010, USA	Health counselors and PCPs	Pedometers used to track PA. Regular phone calls to check in with participants and adjust PA goals as needed.	N/A
First author, year, location	Control group	Effectiveness (PA); effectiveness (HbA1c)	PRECIS-2 score
Middle tertile
Babamoto (CHW) et al., 2009, USAa	Usual care	PA: no HbA1c: no	4.06
De Greef (Group) et al., 2011, Belgiuma	Usual care	PA: yes HbA1c: no	4.06
Van der Weegen (SSP w/ tool) et al., 2015, Netherlands	Usual care	PA: yes HbA1c: NR	4.05
Keyserling (Group B) et al., 2002, USA	Educational pamphlets sent by mail	PA: yes HbA1c: no	4.00
Van der Weegen (SSP) et al., 2015, Netherlandsa	Usual care	PA: no HbA1c: NR	4.00
Edelman et al., 2015, USA	Non-tailored phone calls	PA: no HbA1c: no	3.89
Naik et al., 2011, USA	“Traditional education intervention”	PA: NR HbA1c: yes	3.89
Glasgow (CASM+) et al., 2012, USAa	Enhanced usual care, including additional tailored web-based feedback on health behaviors	PA: yes HbA1c: no	3.85
Francosi et al., 2011, Italy	Standard counseling and routine follow-up	PA: NR HbA1c: yes	3.83
Maindal et al., 2014, UK	Usual care	PA: no HbA1c: no	3.83
Jarab et al., 2012, Jordan	Usual care	PA: yes HbA1c: yes	3.83
Schillinger (ATSM) et al., 2009, USA	Usual care	PA: yes HbA1c: no	3.83
Trento et al., 2008, Italy	Usual care	PA: NR HbA1c: yes	3.83
Trento et al., 2002, Italy	Usual care	PA: NR HbA1c: no	3.81
Barratt et al., 2008, UK	Usual care	PA: NR HbA1c: no	3.78
Bottom tertile
Kim (PM) et al., 2006, South Korea	Usual care	PA: yes HbA1c: yes	3.78
Kim (WB) et al., 2006, South Koreaa	General information sheet from the clinic. Participants visited the clinic once at the beginning of the intervention period	PA: yes HbA1c: yes	3.72
Keyserling (Group A) et al., 2002, USAa	Educational pamphlets sent by mail	PA: yes HbA1c: no	3.69
Schillinger (GMV) et al., 2009, USAa	Usual care	PA: no HbA1c: no	3.67
Anderson et al., 2010, USA	Usual care	PA: NR HbA1c: no	3.67
Lim et al., 2015, South Korea	Dedicated website containing a glucose control section and diet control section	PA: yes HbA1c: yes	3.67
Thoolen et al., 2009, Netherlands	Brochure on diabetes self-management	PA: yes HbA1c: NR	3.63
Taylor et al., 2003, USA	Educational pamphlets and instructions to continue regular care with PCP	PA: NR HbA1c: yes	3.61
Moriyama et al., 2009, Japan	Educational textbook and asked to consult their physician as usual	PA: NR HbA1c: yes	3.56
Van Dyck et al., 2011, Belgium	Usual care	PA: yes HbA1c: NR	3.56
Kim et al., 2011, South Korea	Usual care	PA: yes HbA1c: no	3.50
Sone et al., 2010, Japan	Usual care	PA: yes HbA1c: no	3.46
Uusitupa et al., 1996, Finland	Usual care	PA: no HbA1c: no	3.29
Gaede et al., 1999, Denmark	Usual care	PA: no HbA1c: yes	3.17
Huffman et al., 2010, USA	Usual care	PA: yes HbA1c: NR	3.00

C control group, CHW(s) community health worker(s), hr./hrs. hour/hours, I intervention group, MD(s) doctor(s), min minute/minutes, mo. month/months, N/A not applicable, NR not reported, OP outpatient, PA physical activity, PCP(s)/GP(s) primary care physician(s)/general practitioner(s), RD(s) registered dietitian(s), RN(s) registered nurse(s), wk./wks. week/weeks, yr./yrs. year/years

^aA secondary intervention from an already noted study