The Comparative Effectiveness ofDiabetes Prevention Strategies toReduce Postpartum WeightRetention in Women WithGestational Diabetes Mellitus: TheGestational Diabetes’ Effects onMoms (GEM) Cluster RandomizedControlled TrialDiabetes Care 2016;39:65–74 | DOI: 10.2337/dc15-1254

OBJECTIVE

To compare the effectiveness of diabetes prevention strategies addressing post-partum weight retention for women with gestational diabetes mellitus (GDM)delivered at the health system level: mailed recommendations (usual care)versus usual care plus a Diabetes Prevention Program (DPP)–derived lifestyleintervention.

RESEARCH DESIGN AND METHODS

This study was a cluster randomized controlled trial of 44 medical facilities (in-cluding 2,280 women with GDM) randomized to intervention or usual care. Theintervention included mailed gestational weight gain recommendations plus 13telephone sessions between 6 weeks and 6 months postpartum. Primary out-comes included the following: proportion meeting the postpartum goals of 1)reaching pregravid weight if pregravid BMI <25.0 kg/m2 or 2) losing 5% of pre-gravid weight if BMI ‡25.0 kg/m2; and pregravid to postpartum weight change.

RESULTS

On average, over the 12-month postpartum period, women in the interventionhad significantly higher odds of meeting weight goals than women in usual care(odds ratio [OR] 1.28 [95% CI 1.10, 1.47]). The proportion meeting weight goalswas significantly higher in the intervention than usual care at 6 weeks (25.5 vs.22.4%; OR 1.17 [1.01, 1.36]) and 6 months (30.6 vs. 23.9%; OR 1.45 [1.14, 1.83]).Condition differences were reduced at 12 months (33.0 vs. 28.0%; OR 1.25 [0.96,1.62]). At 6 months, women in the intervention retained significantly less weightthan women in usual care (mean 0.39 kg [SD 5.5] vs. 0.95 kg [5.5]; mean conditiondifference20.64 kg [95% CI21.13,20.14]) and had greater increases in vigorous-intensity physical activity (mean condition difference 15.4 min/week [4.9, 25.8]).

CONCLUSIONS

A DPP-derived lifestyle intervention modestly reduced postpartum weight reten-tion and increased vigorous-intensity physical activity.

1Division of Research, Kaiser Permanente North-ern California, Oakland, CA2School of Nursing and Dental Hygiene, Univer-sity of Hawaii at Manoa, Honolulu, HI3Division ofMetabolism, Endocrinology & Diabe-tes, Department of Internal Medicine, Universityof Michigan, Ann Arbor, MI4Division of Perinatology, Department of Obstet-rics and Gynecology, Kaiser PermanenteMedicalCenter, Santa Clara, CA

Corresponding author: Assiamira Ferrara,assiamira.ferrara@kp.org.

Received 11 June 2015 and accepted 1 Septem-ber 2015.

Clinical trial reg. no. NCT01344278, clinicaltrials.gov.

This article contains Supplementary Data onlineat http://care.diabetesjournals.org/lookup/suppl/doi:10.2337/dc15-1254/-/DC1.

© 2016 by the American Diabetes Association.Readersmayuse this article as longas thework isproperly cited, the use is educational and not forprofit, and the work is not altered.

See accompanying articles, pp. 13, 16,24, 31, 39, 43, 50, 53, 55, and 61.

Assiamira Ferrara,1

MoniqueM. Hedderson,1 Susan D. Brown,1

Cheryl L. Albright,2 Samantha F. Ehrlich,1

Ai-Lin Tsai,1 Bette J. Caan,1

Barbara Sternfeld,1 Nancy P. Gordon,1

Julie A. Schmittdiel,1 Erica P. Gunderson,1

Ashley A. Mevi,1 William H. Herman,3

Jenny Ching,4 Yvonne Crites,4 and

Charles P. Quesenberry Jr.1

Diabetes Care Volume 39, January 2016 65

MANAGEM

ENTOFGESTA

TIONALDIABETES

MELLITU

S

Type 2 diabetes is a costly disease affect-ing ;12.6 million women in the U.S. Ran-domized efficacy trials (1–4) demonstratedthat weight loss programs can prevent di-abetes. Diabetes prevention is critical forwomen with gestational diabetes mellitus(GDM), which affects 7–14% of pregnan-cies (5), as women with GDM are seventimes more likely to develop type 2 diabe-tes than parous women without GDM (6).Postpartum weight retention increases di-abetes risk (7), and postpartum weightmanagement for women with GDM is rec-ommended (8). Yet evidence to supporthealth system adoption of postpartum di-abetes prevention programs for womenwith GDM is lacking. In addition to tradi-tional clinical trials enrolling carefully se-lected volunteers with a history of GDMunder ideal conditions (4), pragmatic trialsevaluating the effectiveness of diabetesprevention programs in real-world clinicalsettings among diverse populations areneeded to increase generalizability and in-form health system adoption (9).The Gestational Diabetes’ Effects on

Moms (GEM) cluster randomized con-trolled trial compared an existing post-partum diabetes prevention programof mailed recommendations deliveredby the Kaiser Permanente NorthernCalifornia (KPNC) Perinatal Center (10)(usual care) to usual care plus a DiabetesPrevention Program (DPP)–derived life-style intervention (1). The DPP-derivedintervention was delivered on behalf ofthe KPNC Perinatal Center and offered asan optional routine care program (11).The goal of the intervention was to helpwomen with GDM 1) reach pregravidweight if their pregravid BMI was,25.0 kg/m2 or 2) lose 5% of pregravidweight if their pregravid BMI was$25.0 kg/m2 (11). Primary outcomeswere the proportion of women whoreached postpartum weight goalsand weight change from pregravid topostpartum across the 12-month post-partum follow-up period. Secondaryoutcomes included changes from preg-nancy to postpartum in daily total energyintake, percent of calories from fat,physical activity, hypertension, and de-pression. An exploratory outcome waspostpartum prediabetes or diabetesincidence.

RESEARCH DESIGN AND METHODS

The rationale and methods of the GEMtrial are described elsewhere (11). The

Kaiser Foundation Research InstituteHuman Subjects Committee approvedthe trial and waived the requirementfor informed consent for the interven-tion. Women provided verbal consentfor the survey component of the trialafter all medical facilities were random-ized (11).

Setting, Randomization, and MaskingThe setting was KPNC, an integratedhealth care delivery system with 44medical facilities managing ;33,000births annually. KPNC membershipclosely approximates the surroundingpopulation (12) and is dynamic with re-spect to enrollment. All 44 KPNC facili-ties were randomized to either usualcare or intervention conditions. Ran-domization was blocked on facility size(i.e., the expected annual number ofwomen with GDM, in three strata:,25, 25–74, and$75). A restricted ran-domization scheme was used to ensureacceptable between-condition balance(i.e., maximum between-condition rela-tive difference) in expected racial/ethnicdistributions and the number of womencontacted by an ongoing unrelated ob-servational study, both overall and withinfacility size stratum (11,13). All investiga-tors, data collectors, and health careproviders were blinded to conditionassignment.

ParticipantsPotentially eligible women includedpregnant women $18 years old diag-nosed with GDM (n = 2,480) accordingto the Carpenter and Coustan criteriabetween March 2011 and March 2012,as recommended by the American Col-lege of Obstetricians and Gynecologists(14) during this period and implementedacross all 44 KPNC medical facilities.Women were excluded if they did nothave any telephone contact with theKPNC Perinatal Center during preg-nancy (n = 142), were missing data onpregravid BMI (n = 40), or had a neonatalloss (n = 18), leaving 2,280 women:1,087 in the intervention condition and1,193 in usual care (Fig. 1). Follow-upended on December 2013.

Usual CareAll women with GDM at KPNC are of-fered supplemental care from the KPNCPerinatal Center consisting of telephone-based case management for glucosecontrol during pregnancy (10). At

6 weeks postpartum, the KPNC PerinatalCenter sends a letter encouragingwomento be screened for diabetes and pro-vides printed materials that emphasize ahealthy BMI, participation in 30 min ofphysical activity daily, and healthy eating.If screening results indicate prediabetes,women are mailedmaterials about life-style prevention strategies and educationalclasses.

DPP-Derived Lifestyle InterventionIn addition to usual care, women attend-ing medical facilities assigned to the in-tervention were mailed, within 2 weeksof the GDMdiagnosis, a tailored letter de-tailing a personalized goal for gestationalweight gain with healthy eating and phys-ical activity tips (11). After delivery,women were offered a print/telephone-based lifestyle program modeled afterthe DPP intervention (11). The programwas presented as optional routine careand delivered by GEM coaches on be-half of the KPNC Perinatal Center. Duringthe core of the postpartum intervention(6 weeks to 6months), the primary targetwas to help women achieve the post-partum weight goals: 1) reaching pre-gravid weight if their pregravid BMIwas ,25.0 kg/m2 or 2) losing 5% of pre-gravid weight if their pregravid BMI was$25.0 kg/m2 (11). Womenweremailed a13-session guidebook to review via tele-phone with a lifestyle coach, a registereddietitian employed for the trial and basedat the KPNC Perinatal Center. Womenwere encouraged to set weekly goalsfor daily fat and caloric intake and to workup to or continue participating in 150minof moderate- to vigorous-intensity physi-cal activity per week (11). Behavior changetechniques were individualized towomen’s preferences, resources, andcultural context usingmotivational inter-viewing and theoretical constructs de-rived from social cognitive theory (15)and the Transtheoretical Model (16). Alltelephone sessions were audiotaped; arandom 10% were coded using a briefchecklist of intervention componentsto assess fidelity to the protocol. Fidel-ity was high (mean proportion of inter-vention components present = 95%,range 60–100%). During the mainte-nance phase (7–12 months postpar-tum), women were mailed threenewsletters encouraging maintenanceof healthy behaviors. Lifestyle coachestracked the time spent scheduling and

66 Diabetes Prevention After GDM Diabetes Care Volume 39, January 2016

conducting telephone sessions. The di-rect cost of the intervention includedcoaches’ work hours, calculated usingthe May 2012 median annual wage forregistered dietitians (17) plus fringebenefits (29% of annual wages), andthe cost of pr int ing and mai l ingmaterials.

Data CollectionAll 2,280 eligible women in the 44 med-ical facilities were invited to completestudy surveys (11); 1,783 (78.2%) com-pleted the baseline survey during preg-nancy after the GDM diagnosis (meangestational age at completion 29.4weeks [SD 6.1]). Survey responders did

not differ from nonresponders exceptfor being less likely to be of non-Hispanicwhite origin (11). Responders to the base-line survey were asked to complete sur-veys at 6weeks, 6months, and12monthspostpartum (11), with 91.6, 87.9, and84.0% retention rates, respectively. Pre-gravid BMI was calculated from clinic-measured pregravid weight obtainedthrough the electronic health record(EHR; 86.0%), weight ascertained at thefirst prenatal clinic visit before 10 weeks’gestation (10.5%, from the EHR), or self-reported pregravid weight on the GEMpregnancy survey (3.5%).

Clinic-measured postpartum weightwas obtained through the EHR for each

time point, regardless of participation inthe intervention or the GEM surveys.Postpartumweightwas also self-reportedat each GEM survey.

The Block Food Frequency question-naire (18) and the Pregnancy PhysicalActivity Questionnaire (19) were usedat baseline and 6 months postpartumto assess usual daily total energy intakeand weekly physical activity over the past3 months. Hypertension was definedas present during pregnancy and ateach postpartum time point by searchingthe EHR for any abnormal blood pres-sure measurements (systolic blood pres-sure $140 mmHg or diastolic bloodpressure$90 mmHg) or for use of antihy-pertensive medications. Depression wasdefined as present during pregnancy andat each postpartum time point bysearching the EHR for diagnoses of de-pression, use of antidepressant medica-tions, or depression score $10 on PatientHealth Questionnaire 9 (PHQ-9) (20) orscore $10 on PHQ-8 (21) from surveysat each time point. Age, race/ethnicity,parity, and laboratory test results werealso obtained from the EHR. Prediabetesand diabetes were defined accordingto American Diabetes Association glyc-emic thresholds (22) (see SupplementaryMethods).

Power and Statistical AnalysisThe sample size of 2,280, of which 97.4%had at least one clinic-measured weightduring the 12-month postpartum follow-up period, allowed for robust estimationof the average effect of the interven-tion on postpartum weight goals as-sessed through clinic-measured weightacross the 12-month postpartum follow-up period. We focused post hoc mini-mum detectable effect estimation ateach point in time accounting for thecluster randomization. Of the sample,93.4, 71.9, and 62.3% had clinic-measuredweight at 6 weeks, 6 months, and 12months postpartum, respectively, whichled to a minimum detectable absolutedifference in the proportion meetingpostpartum weight goals ranging from5.6 to 10.2%, 6.2 to 10.6%, and 6.6 to11.0%, respectively, across the rangein expected proportion meeting goalsin the usual care condition (15–25%,based on our pilot trial [24%] and acrossthe range in expected intraclass corre-lation [0.01–0.05]) (see SupplementaryMethods). We note the additional

Figure 1—Trial flow. a, 12 women were not health plan members and did not have clinic-measured weight, 5 of them provided self-reported weight; b, 9 women were not health planmembers and did not have clinic-measured weight, 4 of them provided self-reported weight;c, 37womenwere not health planmembers and did not have clinic-measuredweight, 26 of themprovided self-reported weight; d, 36 women were not health plan members and did not haveclinic-measuredweight, 25 of them provided self-reported weight; e, 84 womenwere not healthplan members and did not have clinic-measured weight, 61 of them provided self-reportedweight; f, 101 women were not health plan members and did not have clinic-measured weight,66 of them provided self-reported weight only.

care.diabetesjournals.org Ferrara and Associates 67

power and precision gained in the anal-ysis of treatment effects by incorporat-ing the repeated measures of meetingpostpartum weight goals.Analyses were intent to treat. Analy-

ses used marginal regression models toestimate population average interven-tion effects, using logistic regressionwith estimation via generalized estimat-ing equations in analyses of meeting theweight goals and other dichotomousoutcomes, and linear mixed regressionin analyses of weight change and changesin other continuous outcomes afteradjusting for baseline values. Regressionmodels accounted for the within-medicalfacility correlation between patientsand within-person correlation amongrepeated measurements for valid es-timation of treatment effects and as-sociated standard errors. Variations intreatment condition differences overtime were examined via the introduc-tion of appropriate cross-productterms. For all analyses, if women had asubsequent pregnancy, they werecensored at the estimated time ofconception.Primary outcome analysis for the ef-

fect of the intervention included onlyclinic-measured postpartum weights.Sensitivity analyses to address potentialbias from missing clinic-measuredweight included clinic-measured or self-reported postpartum weight collectedduring postpartum surveys. Additionalsensitivity analyses included clinic-mea-sured or imputed postpartum weight(23). The fully conditional specificationimputationmethodwas used, with 10 im-putations performed. Subgroup analyseswere performed after stratifying by pre-gravid BMI. Two exploratory analysesassessed intervention effectivenessacross number of sessions completedand using an instrumental variable to es-timate the complier average causaleffect, a measure of the effectivenessof the intervention among those whocomply with assigned treatment, withthe randomization indicator used as theinstrumental variable (24). For this anal-ysis, “all or none” compliance was de-fined as completing one or moretelephone sessions (25). A key applicableassumption is that the outcomes amongnoncompliers are not affected by ran-domization condition assignment.Exploratory outcome analysis of predia-betes or diabetes incidence used Cox

proportional hazards regression to esti-mate hazard ratios associated with theintervention, controlling for pregnancyfasting and 3-h glucose values and pre-gravid BMI. All analyses were conductedusing SAS 9.3 (Cary, NC).

RESULTS

The intervention and usual care condi-tions were comparable on prerandom-ization characteristics such as medicalfacility size (Fig. 1) and racial/ethnicand BMI distributions; however, they dif-fered by fasting and 3-h glucose (Table 1).Among the 1,087 women in the inter-vention, 50.3% completed one ormore telephone sessions; specifically,18.8% completed 1–3 sessions, 16.2%completed 4–12 sessions, and 15.3%completed all 13 sessions.

Primary OutcomesClinic-measured postpartumweight wasobtained at least once during the 12-month postpartum follow-up for 97.4%ofwomen (n = 2,221). In the primary anal-ysis that included only clinic-measuredpostpartum weight, on average, overthe 12-month postpartum period, womenin the medical facilities assigned to theintervention had a statistically signifi-cant 28% higher odds (odds ratio [OR]1.28 [95% CI 1.10, 1.47]) of meeting post-partum weight goals than women in themedical facilities assigned to usual care(Table 2). The proportion meetingweight goals was significantly higher inthe intervention facilities than usualcare facilities at 6 weeks (25.5 vs.22.4%; 1.17 [1.01, 1.36]) and 6 monthspostpartum (30.6 vs. 23.9%; 1.45 [1.14,1.83]). At 12 months (6 months after theintervention ended), the condition dif-ference was reduced (33.0 vs. 28.0%;1.25 [0.96, 1.62]) and no longer statisti-cally significant. The absolute differencebetween conditions was 3.1% at 6weeks, 6.7% at 6 months, and 5.0% at12 months postpartum. In analyses ex-amining weight change from pregravidto postpartum (Table 2), women in theintervention facilities retained lessweight than women in usual care facili-ties at 6 months postpartum (mean0.39 kg [SD 5.5] vs. 0.95 kg [5.5]; adjustedmean condition difference 20.64 kg[95% CI 21.13, 20.14]); the conditiondifference was attenuated at 12 monthspostpartum and no longer statisticallysignificant (20.43 kg [20.98, 0.11])

(Table 2). Sensitivity analyses that in-cluded self-reported or imputed weightif the clinic-measured weight was miss-ing yielded similar results (Tables 2 and3). The intervention was equally effec-tive across racial/ethnic groups (P valuefor condition 3 race/ethnicity interac-tions .0.25). The intervention was alsoequally effective across BMI strata(Supplementary Tables 1 and 2).

In exploratory analyses, the instru-mental variable estimates of the abso-lute differences between conditionsamong compliers (defined as complet-ing one or more telephone sessions)were almost double the absolute differ-ences observed in the primary analysis:estimates for proportions meetingweight goals were 6.2% at 6 weeks,13.3% at 6 months, and 9.9% at12 months; estimates for differences inmean weight change were 20.62 kg at6 weeks, 21.27 kg at 6 months, and20.86 kg at 12 months postpartum.

In additional exploratory analyses,women who completed all 13 sessionshad significantly higher odds of meet-ing the postpartum weight goals thanwomen in usual care at 6 months (3.97[2.75, 5.72]) and 12 months postpar-tum (2.16 [1.52, 3.07]) (Fig. 2A). In anal-yses examining weight change frompregravid to postpartum (Fig. 2B), womenwho completed 4–12 sessions retainedless weight than women in usual careat 6 months postpartum (mean 0.13 kg[SD 5.7] vs. 0.94 kg [5.5], adjusted meancondition difference 21.1 kg [95% CI21.8, 20.41]) and at 12 months post-partum (0.06 kg [5.6] vs. 0.50 kg [5.4];21.0 kg [21.9, 20.13]). Women whocompleted all 13 sessions lost moreweight than women in usual care at6 months (mean 21.89 kg [SD 5.5] vs.0.94 kg [5.5], adjusted mean conditiondifference22.3 kg [95% CI23.1,21.5])and 12 months postpartum (21.19 kg[6.1] vs. 0.50 kg [5.4]; 21.6 kg [22.4,20.68]).

Secondary OutcomesAt 6 months postpartum, women in bothconditions increased minutes per weekspent in vigorous-intensity activity; how-ever, women in the intervention facilitiesshowed a significantly greater increase(adjusted mean condition difference 15.4min/week [95% CI 4.9, 25.8]) (Table 3). Nocondition differences were observed fortime spent in moderate-intensity activity

68 Diabetes Prevention After GDM Diabetes Care Volume 39, January 2016

Table 1—Baseline characteristics by treatment condition: the GEM trial

Intervention, N = 1,087 Usual care, N = 1,193 Entire sample, N = 2,280

n (%) n (%) n (%)

Age (years)18–24 59 (5.4) 58 (4.9) 117 (5.1)25–29 238 (21.9) 289 (24.2) 527 (23.1)30–34 425 (39.1) 425 (35.6) 850 (37.3)35–39 280 (25.8) 330 (27.7) 610 (26.8)40–50 85 (7.8) 91 (7.6) 176 (7.7)

Race-ethnicityAsian 458 (42.1) 481 (40.3) 939 (41.2)Non-Hispanic white 268 (24.7) 305 (25.6) 573 (25.1)Hispanic 236 (21.7) 270 (22.6) 506 (22.2)African American 47 (4.3) 57 (4.8) 104 (4.6)Multiracial 37 (3.4) 37 (3.1) 74 (3.3)Other 26 (2.4) 16 (1.3) 42 (1.8)Pacific Islander 13 (1.2) 25 (2.1) 38 (1.7)Missing 2 (0.2) 2 (0.2) 4 (0.2)

Pregravid BMI (kg/m2)15.9–19.9 61 (5.6) 59 (5.0) 120 (5.3)20.0–24.9 324 (29.8) 343 (28.8) 667 (29.3)25.0–29.9 319 (29.4) 352 (29.5) 671 (29.4)30.0–34.9 201 (18.5) 216 (18.1) 417 (18.3)35.0–59.7 182 (16.7) 223 (18.7) 405 (17.8)

Parity0 451 (41.5) 501 (42.0) 952 (41.8)1 363 (33.4) 398 (33.4) 761 (33.4)2 174 (16.0) 157 (13.2) 331 (14.5)3+ 84 (7.7) 117 (9.8) 201 (8.8)Missing 15 (1.4) 20 (1.7) 35 (1.5)

HypertensionYes 80 (7.4) 82 (6.9) 162 (7.1)No 1,005 (92.5) 1,111 (93.1) 2,116 (92.8)Missing 2 (0.2) 0 (0) 2 (0.1)

DepressionYes 206 (19.0) 237 (19.9) 443 (19.4)No 833 (76.6) 887 (74.4) 1,720 (75.4)Missing 48 (4.4) 69 (5.8) 117 (5.1)

Mean (SD) Mean (SD)

Pregravid body weight (kg) 73.5 (19.9) 74.7 (20.2) 74.2 (20.0)

Pregravid BMI (kg/m2) 28.5 (6.8) 28.9 (6.9) 28.7 (6.8)

BMI at GDM diagnosis (kg/m2) 31.0 (6.5) 31.4 (6.4) 31.2 (6.5)

Gestational age at GDM diagnosis (weeks) 25.2 (6.4) 25.3 (6.6) 25.3 (6.5)

100-g, 3-h OGTTFasting glucose (mmol/L)* 5.0 (0.7) 5.1 (0.7) 5.1 (0.7)1-h glucose (mmol/L) 11.0 (1.4) 11.1 (1.5) 11.0 (1.4)2-h glucose (mmol/L) 9.8 (1.5) 9.8 (1.5) 9.8 (1.5)3-h glucose (mmol/L)* 7.3 (1.8) 7.1 (1.8) 7.2 (1.8)

Systolic blood pressure (mmHg) 116.7 (13.0) 116.7 (13.6) 116.7 (13.3)

Diastolic blood pressure (mmHg) 72.9 (10.0) 72.6 (10.2) 72.7 (10.1)

Daily total energy intake (kcal/day)† 1,743.5 (662.5) 1,736.7 (660.7) 1,740.0 (661.4)

Daily percent of kcal from fat† 42.2 (7.0) 42.2 (7.0) 42.2 (7.0)

Walking (min/week)‡ 446.3 (355.2) 427.9 (364.1) 436.8 (359.8)

Moderate physical activity (min/week)‡ 38.2 (62.9) 32.1 (55.8) 35.1 (59.4)

Vigorous physical activity (min/week)‡ 23.5 (53.3) 19.0 (46.2) 21.2 (49.8)

Total volume of physical activity (MET min/week)‡ 1,667.9 (1,312.9) 1,554.4 (1,212.6) 1,609.2 (1,262.7)

Hypertension was defined as systolic blood pressure $140 mmHg, diastolic blood pressure $90 mmHg, or use of antihypertensive medications.Depression was defined as score $10 on PHQ-8 or PHQ-9, physician diagnosis, or use of antidepressant medications. OGTT, oral glucosetolerance test. *P, 0.05 for the comparisonwith the intervention condition by two-tailed Student t test. All other comparisons had a P$ 0.05. †639women in the intervention and 668 women in usual care with valid diet data at baseline and 6 months postpartum (e.g., those with daily totalenergy intake$600 and#4,000 kcal at both time points). ‡522 women in the intervention and 560 women in usual care with valid physical activitydata at baseline and 6 months postpartum (e.g., those with#20 h/week of total physical activity and #9 h/week of moderate physical activity atboth time points).

care.diabetesjournals.org Ferrara and Associates 69

Table

2—Pro

portion

ofwomen

mee

ting

thepostpartum

weightgoals

with

ORsestim

ating

difference

sbetw

een

conditionsand

mea

nch

anges

inweightfrom

pregravid

topostpartum

withmea

ndifference

sbetweenco

nditions:

theGEM

trial

Prim

aryanalysis

Sensitivity

analysis

Measuredpostpartum

weigh

tsMeasuredorself-rep

orted

postpartum

weights

Measuredorim

puted

postpartum

weigh

tsInterven

tion

Usualcare

Interven

tion

Usualcare

n%meeting

weigh

tgoals

n%meeting

weightgoals

OR(95%

CI)

Pvalue*

n%meeting

weigh

tgoals

n%meeting

weigh

tgoals

OR(95%

CI)

Pvalue*

OR(95%

CI)

Pvalue*

Average

effect

ofinterven

tion

1,05

11,17

01.28

(1.10,

1.47

),0.01

1,07

51,18

71.23(1.08,

1.39)

,0.01

1.25(1.11,

1.42)

,0.01

6weeks

postpartum

1,00

025

.51,12

922

.41.17

(1.01,

1.36

)0.04

1,05

025

.01,15

622

.71.16(1.00,

1.34)

0.05

1.18(0.98,

1.44)

0.09

6months

postpartum

764

30.6

875

23.9

1.45

(1.14,

1.83

),0.01

922

31.6

1,04

525

.41.37(1.13,

1.67)

,0.01

1.33(1.09,

1.62)

0.01

12months

postpartum

676

33.0

744

28.0

1.25

(0.96,

1.62

)0.09

890

33.5

967

30.2

1.16(0.95,

1.41)

0.14

1.24(0.97,

1.59)

0.08

nMean

weight(SD)

nMean

weigh

t(SD)

Adjusted

†mean

weightcondition

difference

(95%

CI)

Pvalue*

nMean

weight(SD)

nMean

weight(SD)

Adjusted

†mean

weigh

tcondition

difference

(95%

CI)

Pvalue*

Adjusted

†mean

weigh

tcondition

difference

(95%

CI)

Pvalue*

Average

effect

ofinterven

tion

1,05

11,17

020.29

(20.69

,0.11)

0.16

1,07

51,18

720.26(2

0.65,

0.13)

0.19

20.24(2

0.67,

0.19)

0.28

6weeks

postpartum

1,00

00.64(5.57)

1,12

90.75(5.46)

20.21

(20.64

,0.23)

0.35

1,05

00.64

(5.53)

1,15

60.71(5.44)

20.20(2

0.63,

0.22)

0.35

20.19(2

0.63,

0.26)

0.41

6months

postpartum

764

0.39(5.55)

875

0.95(5.47)

20.64

(21.13,20.14)

0.01

922

0.17

(5.46)

1,04

50.64(5.54)

20.55(2

1.02

,20.09)

0.02

20.51(2

0.99

,20.02)

0.04

12months

postpartum

676

0.20(5.84)

744

0.50(5.43)

20.43

(20.98

,0.11)

0.12

890

0.01

(5.81)

967

0.15(5.73)

20.32(2

0.82,

0.19)

0.22

20.35(2

0.98,

0.29)

0.28

*Pvalueforconditiondifferences;Pvalues

fortreatm

ent3

follow-uptimepointinteraction.0.05.

†Adjusted

forpregravid

weigh

t.

70 Diabetes Prevention After GDM Diabetes Care Volume 39, January 2016

Table

3—Meanch

angesin

physica

lactivity

anddietfro

mpregnancy

to6month

spostp

artu

mwith

meandiffe

rence

sbetw

eenco

nditio

ns:

theGEM

trial

Primary

analysis

Sensitivity

analysis

Self-reported

data

Self-reported

orim

puted

data

Interven

tion

Usualcare

Interven

tion

Usualcare

nMean

(SD)

nMean

(SD)

Adjusted

*mean

conditio

ndifferen

ce(95%

CI)

nMean

(SD)

nMean

(SD)

Adjusted

*mean

conditio

ndifferen

ce(95%

CI)

Moderate

activity(m

in/w

eek)Durin

gpregn

ancy

52238.2

(62.9)560

32.1(55.8)

1,08339.1

(2.6)1,187

34.1(2.5)

6months

postp

artum

52242.8

(67.2)560

33.7(61.8)

1,08347.0

(2.5)1,187

35.4(3.1)

Mean

change

(95%CI)

4.5(2

1.8,10.8)1.6

(24.5,7.7)

7.0(2

0.8,14.7)8.0

(1.8,14.1)1.9

(26.5,10.3)

9.5(0.7,18.3)

Vigo

rousactivity

(min/w

eek)Durin

gpregn

ancy

52223.5

(53.3)560

19.0(46.2)

1,08322.9

(1.8)1,187

19.6(1.6)

6months

postp

artum

52247.2

(78.9)560

30.6(68.4)

1,08347.6

(2.9)1,187

32.5(2.9)

Mean

change

(95%CI)

23.7(16.9,30.5)

11.7(5.1,18.2)

15.4(4.9,25.8)

24.9(18.0,31.7)

13.3(6.3,20.3)

14.0(5.0,22.9)

Totalvo

lumeof

physicalactivity

(MET

min/w

eek)Durin

gpregn

ancy

5221,667.9

(1,312.9)560

1,554.4(1,212.6)

1,816.6(58.6)

1,781.7(53.3)

6months

postp

artum

5221,753.9

(1,300.5)560

1,610.0(1,354.7)

1,843.0(64.4)

1,727.6(54.0)

Mean

change

(95%CI)

88.0(2

48.5,224.6)58.4

(279.1,195.9)

113.8(2

78.0,305.6)1,083

33.5(2

135.8,202.8)1,187

247.4

(2203.0,108.3)

100.5(2

83.7,284.7)

Daily

totalen

ergyintake

(kcal)Durin

gpregn

ancy

6391,763.1

(655.7)668

1,740.2(644.1)

1,754.6(28.4)

1,785.7(26.4)

6months

postp

artum

6391,591.4

(614.7)668

1,583.4(608.0)

1,580.4(27.5)

1,622.7(25.9)

Mean

change

(95%CI)

2171.8

(2221.2,2

122.4)2153.9

(2203.7,2

104.1)25.3

(264.6,53.9)

1,0832175.5

(2232.9,2

118.1)1,187

2162.7

(2214.8,2

110.6)226.6

(288.3,35.1)

Daily

percen

tof

calories

from

fatDurin

gpregn

ancy

63942.1

(6.9)668

42.2(7.0)

42.0(0.3)

42.2(0.3)

6months

postp

artum

63940.2

(6.3)668

39.8(6.7)

40.1(0.3)

39.8(0.3)

Mean

change

(95%CI)

21.8

(22.5,2

1.1)22.3

(23.0,2

1.6)0.4

(20.3,1.1)

1,08322.0

(22.6,2

1.3)1,187

22.4

(23.1,2

1.8)0.3

(20.4,1.1)

*Adjusted

forbaselin

evalu

es.

care.diabetesjournals.org Ferrara and Associates 71

or total volume of activity (i.e., MET min-utes per week). Women in interventionfacilities and usual care facilities reportedsimilar reductions in daily total energy in-take and percent of calories from fat, withno condition differences (Table 3). Similarresults for diet and physical activity wereobserved in sensitivity analyses that in-cluded imputed values if survey datawere missing (Table 3). No condition dif-ferences were observed for hypertensionor depression (Supplementary Table 3).

Exploratory OutcomesAfter excludingwomenwith possible pre-gestational diabetes (21 in the interven-tion and 29 in usual care), 873 (83.5%)women in the intervention and 974

(85.4%) in usual care completed postpar-tum diabetes screening. Fewer women inthe intervention facilities developed pre-diabetes or diabetes than in usual carefacilities (310 [29.7%] and 37 [3.5%] inintervention facilities and 370 [32.4%]and 50 [4.4%] in usual care facilities, re-spectively). However, the risk estimatefor prediabetes/diabetes combined didnot reach statistical significance (33.2 vs.36.8%; hazard ratio 0.90 [95% CI 0.78,1.04]) (Supplementary Fig. 1).

Intervention Process Measures andEconomic CostThe mean number of call attempts toreach women and complete telephonesessions was 2.2 (SD 1.8). The first

session lasted a mean of 28.2 min(8.6); subsequent sessions lasted amean of 18.8 min (7.4). Direct interven-tion costs per person among all 1,087women in the intervention were$78.00 ($19.00 for printing and mailingand $59.00 for telephone sessions);costs increased to $121.00 ($19.00 forprinting and mailing and $102.00 fortelephone sessions) if the cost of tele-phone sessions was calculated amongwomen who completed one or moretelephone sessions.

Adverse EventsDuring the 12 months postpartum,there were no significant differences be-tween intervention and usual care in theproportion of women who had an emer-gency room visit for sprains/strains (n =9 [0.8%] vs. n = 16 [1.3%]; P = 0.24) orfractures (n = 2 [0.2%] vs. 6 [0.5%]; P =0.29). The proportion of women in theintervention and usual care who werehospitalized or had an emergencyroom visit was 2.1 vs. 1.8% (P = 0.64)and 7.8 vs. 10.1% (P = 0.05), respec-tively. No condition differences wereobserved in underlying medical diagno-sis except that fewer women had emer-gency room visits due to gallbladderdisorders in the intervention thanusual care (n = 3 [0.3%] vs. n = 15 [1.2%];P = 0.008).

CONCLUSIONS

This cluster randomized trial demon-strated that a health system–basedprint/telephone lifestyle interventionderived from the DPP modestly reducedpostpartum weight retention and in-creased vigorous-intensity physicalactivity among women with GDM.Postpartum weight retention andweight gain are associated with in-creased risk for diabetes (7), recurrentGDM (26), and abnormal cardiometa-bolic profile (27). The reductions inpostpartum weight retention and thesuggestion of reductions in prediabetes/diabetes incidence, for which GEM wasnot powered, might be explained bythe significant increase in vigorous-intensity activity among women in theintervention facilities, since no conditiondifferences were observed for changesin daily total energy intake and percentof calories from fat. It has been reportedthat vigorous-intensity activity is associ-ated with decreased risk of diabetes

Figure 2—OR (95% CI) estimating the condition difference in meeting the postpartum weightgoals (A) and adjusted mean condition difference (95% CI) (B) for weight change from pregravidby number of intervention sessions completed and time since delivery: the GEM trial. At6 months postpartum, the number of women by number of completed telephone sessionswere as follows: 338 for 0 sessions, 151 for 1–3 sessions, 171 for 4–12 sessions, and 104 for13 sessions. At 12 months, the number of women by number of completed telephone sessionswere as follows: 301 for 0 sessions, 134 for 1–3 sessions, 112 for 4–12 sessions, and 129 for13 sessions.

72 Diabetes Prevention After GDM Diabetes Care Volume 39, January 2016

among women with a history of GDM(28) and greater sports participation isassociated with reduced postpartumweight retention (27).Condition differences in weight ob-

served in GEM were similar to that ob-served in other cluster randomizedtrials. In the Tianjin Gestational DiabetesPrevention Program cluster randomizedtrial (29), women in a lifestyle interven-tion weighed ;1 kg less than women inthe control condition at 12 months post-partum. The GEM condition differencewas also similar to that observed at 12months in the Da Qing cluster random-ized trial (3) of adults with prediabetes,in which lifestyle intervention led to 40and 60% reductions in diabetes risk at6 years (3) and 20 years (30), respectively,suggesting potential long-term beneficialeffects of modest weight loss. In GEM,condition differences in the proportionmeeting postpartum weight goals werestatistically significant, on average, overthe entire 12-month postpartum period,andat 6weeks and 6months postpartum.Although condition differences at the 12-month postpartum time point were notstatistically significant, they were similarin magnitude to those at 6 months post-partum, when the intervention ended.It is noteworthy that intervention effects

on postpartum weight retention amongwomen with GDM are greater in trials ran-domized at the individual level (31,32) thancluster randomized trials (29), since only aselect group of motivated volunteers par-ticipate in the former. Although in clusterrandomized trials such as GEM only a por-tion of eligiblewomen participate, it shouldbe noted that the effect sizes reported arefor all women in the facilities assigned tothe intervention. Instrumental variableanalysis suggested that the intervention ef-fect would be at least twofold greater if allwomen had completed one or more ses-sions, suggesting a potential for great im-pact if we can improvepatient engagementin such lifestyle interventions. To illustrate,in the pilot study that preceded GEM, withrandomization at the individual level, morewomen in the intervention met the post-partum weight goals, with a 16% absolutedifference between conditions by 12months postpartum (31). A trial among75 women with GDM found women in aweb-based lifestyle intervention werecloser to their pregravid weight than con-trol subjects at 12 months postpartum(20.7 vs. +4.0 kg) (32).

Limitations of the GEM trial includemissing clinic-measured weight for26.4% of women at 6 months and32.7% at 12 months postpartum. Thesemissing data are due to the pragmaticnature of the GEM trial; participantsdid not volunteer for a study with12 months of longitudinal follow-up onbody weight measurements. We ob-tained women’s weights from the EHR,although this required women to visittheir medical facility. Still, 97.4% ofwomen contributed to the analysis ofmeasured weight across the entire12-month postpartum period. Further-more, results based on clinic-measuredpostpartum weight were comparable tothose of sensitivity analyses. Observeddifferences in postpartum weight reten-tion remained significant in a sensitivityanalysis that included clinic-measuredweight or self-reported weight (with only13.7 and 18.6% still missing at 6 and12 months, respectively) and a sensitivityanalysis that imputed missing clinic-measured weight. Given the robustnessof our results, it is unlikely that missingclinic-measured weight data created bias.

Strengths of this cluster randomizedtrial include the ability to randomize allmedical facilities in the KPNC region; thelarge number of facilities andwomen, andtheir racial/ethnic diversity; intent-to-treat analyses including all facilities andwomen; blinding of investigators, datacollectors, and health care providers;and follow-up extending 6 months be-yond the end of the intervention. Aunique strength was that the primaryanalysis was based on clinic-measuredweight obtained via EHR, regardless ofwomen’s participation in the surveys orintervention. These features provide gen-eralizable, real-world findings.

GEM features several aspects of prag-matic trials, which prioritize generaliz-ability at the potential expense ofeffect size given implicit sample hetero-geneity and lower intervention adher-ence (33). In contrast to traditionalclinical trials, GEM had minimal exclu-sion criteria and the intervention wasdelivered at the health system level asoptional routine care to an unselectedpopulation (i.e., regardless of motiva-tion, perinatal complications, or comor-bidities), which likely contributed to the50.3% intervention uptake. Althoughthis uptake is high for a pragmatic trial(34,35)dand considerably higher than,

for example, the recently reported up-take of 13% in the health system–basedVeterans Health Administration MOVE!lifestyle change program, the largestsuch program in the U.S. (36)duptakelikely impacted the condition differ-ences observed and shows how chal-lenging it is to engage patients inprevention programs. In GEM, interven-tion effectiveness increased with thenumber of sessions completed. Al-though prespecified categories for thenumber of completed sessions wereused, women were not randomized tothese categories, and those who com-pleted more sessions may have lostmore weight due to increased motiva-tion for a healthy lifestyle. Nevertheless,these dose-response analyses (37) sug-gest that to increase the effectiveness oflifestyle interventions, strategies areneeded to increase and sustain patientengagement. If health systems were toadopt postpartum interventions forwomen with GDM, clinician referralsand other strategies to increase patientengagement might increase uptake andeffectiveness (38). Finally, the cost perwoman of the GEM intervention was rela-tively modest, and the printed/telephonemodality is easily translatable to othersettings.

In conclusion, this cluster randomizedtrial of diabetes prevention strategiesdelivered at the health system level towomen with GDM demonstrated that aDPP-derived, print/telephone-based life-style intervention was superior to usualcare in reducing postpartum weight reten-tion, a risk factor for diabetes, and in-creasing physical activity. Althoughcondition differences were modest, dif-ferences of similar magnitude havebeen shown to reduce long-term diabe-tes incidence in at-risk adults (30).These findings, from a trial embeddedin real-world practice, may encouragehealth systems to adopt DPP-derivedpostpartum interventions to help womenwith GDM manage their weight andincrease physical activity, thereby po-tentially preventing or delaying the on-set of diabetes.

Acknowledgments. The authors thank themembers of KPNC who participated in thetrial. The authors also thank members ofthe trial Data and Safety Monitoring Board(Dr. Dennis M. Black [University of California,

care.diabetesjournals.org Ferrara and Associates 73

San Francisco], Dr. Thomas A. Buchanan [Univer-sity of Southern California], and Dr. Bess Marcus[University of California, San Diego]) for theirhelpful comments and suggestions.Funding. This research was supported by theAgency for Healthcare Research and Quality(grant R01-HS-019367) and the National Insti-tute of Diabetes and Digestive and Kidney Dis-eases (grant R18-DK-067334). A.F. also receivedsupport from grant P30-DK-092924 from theNational Institute of Diabetes and Digestiveand Kidney Diseases. S.D.B. also received sup-port from grant K01-DK-099404 from the Na-tional Institute of Diabetes and Digestive andKidney Diseases.The authors collected, analyzed, and inter-

preted the data and drafted the manuscriptindependently from the sponsors.Duality of Interest. No potential conflicts ofinterest relevant to this article were reported.Author Contributions. A.F., M.M.H., S.D.B.,and C.P.Q. conceived and designed the study;acquired, analyzed, and interpreted data; anddrafted and critically revised the manuscript forimportant intellectual content. C.L.A. conceivedand designed the study and critically revised themanuscript for important intellectual content.S.F.E.acquired,analyzed,and interpreteddataanddrafted and critically revised the manuscript forimportant intellectual content. A.-L.T. analyzedand interpreted data. B.J.C., B.S., N.P.G., J.A.S.,E.P.G., A.A.M., W.H.H., and J.C. acquired data.Y.C. conceived anddesigned the study, acquireddata, and critically revised the manuscript forimportant intellectual content. A.F. is the guar-antor of this work and, as such, had full access toall the data in the study and takes responsibilityfor the integrity of the data and the accuracy ofthe data analysis.Prior Presentation. Some of these data werepresented at the 74th Scientific Sessions of theAmerican Diabetes Association, San Francisco,CA, 13–17 June 2014, and at the Obesity Soci-ety’s Annual Scientific Meeting, Boston, MA,2–7 November 2014.

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