First versus repeat treatment with a lifestyle intervention program: attendance and weight loss outcomes

Abstract

Objective: Following unblinding of the Diabetes Prevention Program (DPP) results, a 16-session lifestyle intervention program was offered to all study participants, including those who had initially been randomized to lifestyle treatment. This study compares the effects of the lifestyle program between participants who had previous exposure and those who had not.

Design: A 16-session behavioral intervention was conducted in groups at each of the 27 DPP sites during a transitional (bridge) period from the DPP trial to the DPP Outcomes Study (DPPOS). Session participation for this 6-month behavioral weight loss program was confirmed by originally randomized treatment groups.

Subjects and measurements: Independently assessed weight measurements were available within a 7-month period before and after the program for 2808 ethnically diverse participants.

Results: Participants from the lifestyle group in the DPP were the least likely to attend a repeat offering of a 16-session behavioral weight loss program conducted in groups. Weight loss during the transitional lifestyle program was strongly related to the duration of attendance in the three groups that were participating in the program for the first time (metformin, placebo and troglitazone), but not related to amount of earlier weight loss.

Conclusion: Individuals who were naive to the behavioral program lost a greater amount of weight and this was strongly related to their degree of participation. A second exposure to a behavioral weight loss program resulted in unsatisfactory low attendance rates and weight loss.

Figure 1

Timeline of intervention periods. Treatment period timeline and DPP main trial enrollment to DPPOS. All DPP participants (n=3819) were randomized by June, 1999, resulting in an average follow-up period of 3.2 years. Bridge period HELP program was administered during a fixed 6-month period and offered to all remaining participants (n=3727).

Figure 2

HELP session participation (out of 16) by pre-HELP weight change. From left to right, the four bars in each treatment group represent participant quartiles of pre-HELP weight change (kg), from greatest weight loss to greatest weight gain, by the mean of sessions attended out of 16. The average of pre-HELP weight change in each quartile is shown at the bottom. Weight change before beginning HELP was not associated with joining for MET, PLAC, TROG (NS; P>0.05). *Lifestyle participants who had gained the most weight since baseline (average=5.0 kg) had a significantly lower rate of joining HELP (P<0.05) when compared with the participants in the first and second quartiles (average weight loss at 13.6 and 5.6 kg).

Figure 3

Bridge participation and weight change. From left to the right, the four bars in each treatment group represent rate of HELP session participation (either 0, 1–5, 6–11, or 12–16) by weight change in kg.

Figure 4

Long-term weight change in DPP and beginning of DPPOS. Weight change per 6-month visit interval by the four DPP treatment groups are represented as follows: triangle—troglitazone; open circle—placebo; open square—metformin; diamond—lifestyle.

Figure 5

Weight change by treatment group based on calendar time. Calendar time weight change (from the end of randomization) by the four DPP treatment groups are represented as: diamond with dotted line—placebo; square with dashed line—metformin; triangle with dashed line— lifestyle; square with solid line—troglitazone.