Study Overview
Objective. To determine whether in-person visits for primary care patients resulted in improved weight loss maintenance relative to monthly mailings, with both groups receiving access to portion-controlled meals.
Design. Randomized clinical trial.
Setting and participants. This study took place within 2 university-affiliated primary care clinics in Colorado. For the first phase of the study, investigators enrolled 104 obese adult patients (18–79 years; BMI 30–49.9 kg/m 2) who had been diagnosed with at least one of the following: type 2 diabetes, sleep apnea, hypertension, or hyperlipidemia. Patients who had independently lost weight prior to trial entry (> 5% in 6 months), were on weight-gain–promoting medications such as steroids, or had previously undergone bariatric surgery were excluded. The trial started with a 6-month run-in phase where active weight loss was promoted using a high-intensity behavioral intervention based on the Diabetes Prevention Program as well as access to subsidized portion-controlled foods (Nutrisystem). At the end of the 6-month run-in, the remaining participants ( n = 84, 79.3%) were then randomized, stratified by gender and whether or not they achieved 5% weight loss, into the 2 main study arms.
Intervention. The experimental study arm ( n = 41, “intensified maintenance”) relied on monthly in-person visits and monthly phone calls to prevent weight regain (thus, these participants had twice monthly contact during maintenance). Both visit types in this arm were conducted by a graduate-level research assistant and included some structured educational content as well as problem-solving around diet and lifestyle issues. In contrast, the control arm ( n = 43, “standard maintenance”) relied just on monthly mailings (or emails) of educational and support materials to promote weight loss maintenance. Participants in both groups had the opportunity to purchase subsidized portion-controlled foods/meals from Nutrisystem in order to facilitate continued adherence to the caloric restriction required for weight loss maintenance.
Main outcome measures. The primary outcome for this trial was change in weight, measured in kgs, during the 12-month maintenance period. Other biometric outcomes included changes in blood pressure, serum glucose, lipid levels, and the inflammatory marker hs-CRP. Patient-reported outcomes included changes in medication use. The investigators used intention-to-treat analysis, with mixed linear models adjusted for age and gender. No imputation techniques for missing data are reported, although complete follow-up data was obtained on 94% of patients.
Results. Participants in the standard and intensified weight maintenance arms of the trial were similar with respect to measured baseline characteristics. The average age of participants was 56 years, and three-quarters (75%) were female. The majority in both groups were white (77% in standard arm; 88% in intense), and over half had either a college or advanced degree (58.1% in standard arm, 51.2% in intense). Approximately one- third had diabetes (32.6% in standard arm, 34.1% in intense) and over half had hypertension (67.4% in standard arm, 63.4% in intense). Of the 84 participants who were randomized in the weight maintenance phase of the study, 79 completed the 12-month follow up (94%; no difference in attrition between groups).
After 12 months of maintenance, participants in the intensified maintenance arm regained just 1.6 (± 1.3) kg of lost weight, while those in the standard arm regained 5.0 (± 0.8) kg, a statistically significant difference ( P = 0.01). The investigators also examined the subgroup of participants who, after the 6-month run-in, had lost at least 5% of their initial body weight. For these individuals, almost three-quarters in the intensified maintenance arm (71.9%) maintained that > 5% loss by 18 months, compared to 51.7% in the standard group. This difference between groups was not statistically significant. There was a significant difference between groups for change in hs-CRP over the 12-month maintenance period, with the intensive group’s hs-CRP ending up an average of 1.46 mg/L lower than that of the standard group ( P = 0.03). Although there was a similar trend favoring the intensive intervention for other biometric measures (change in waist circumference, glucose, blood pressure, and lipids were all more favorable in this arm), the between-group differences for these measures did not reach statistical significance. No significant differences between groups were observed with respect to changes in medication use over the 12-month maintenance intervention.
Conclusion. After 5 months of active weight loss, twice-monthly contact (using one in-person and one phone visit) plus portion-controlled foods during a 12-month weight maintenance phase resulted in significantly less weight regain than monthly mail or email-based counseling plus portion-controlled foods.
Commentary
Behavioral weight loss interventions, which typically require high-intensity in-person counseling over several months to a year, may be difficult to accomplish in the average primary care practice [1]. On the other hand, it may be the case that primary care practices are well-suited to assist patients who have already lost weight, as they enter weight-loss maintenance. While numerous studies have shown that patients who adhere to calorie-restricted diets (almost regardless of diet composition) are able to achieve clinically significant weight loss, less is known about effective methods of preventing weight regain. Several large trials have suggested that, as is the case with behavioral weight loss interventions, maintenance interventions are also more successful if they include regular contact, at least some of which is face-to-face [2,3]. These visits, along with other practices such as self-weighing and food diaries, may help patients maintain the energy balance necessary to stay at their new, lower body weight. There remains a gap, however, in terms of knowing whether the maintenance interventions from large randomized trials can be translated into the sometimes messy real world of clinical practice, where clinicians and patients are typically overburdened and busy.
The current study by Tsai et al does address some aspects of this important question. By recruiting “real-world” chronically ill patients from a primary care practice to participate in the trial, the results of this study may be more likely to generalize to the patient populations seen by practicing clinicians than the typically healthier, younger, community-recruited volunteers in large trials. Additionally, although the interventions in this study were not delivered by the primary care practice per se, they were low enough in intensity that they could theoretically be translated into most clinical practice settings, assuming reimbursement is not an issue. Monthly in-person visits certainly could be done by a physician (as under current CMS reimbursement guidelines), but would not have to be (the visits in this study were done by a graduate student with no formal training in behavioral interventions), and telephone visits could easily be done by clinical support staff. Even with this low level of visit intensity, patients had significantly less weight regain than those who were receiving monthly email or postal mail support (which, realistically, would still require some work on the part of primary care practices). Furthermore, there were suggestions of numerous parallel cardiometabolic benefits that might have been statistically significant with a larger sample size. This study benefited from several strengths in addition to its highly practical point of view. It was a randomized trial with a strong control group and long follow-up duration (18 months total). It used a run-in period for weight loss so that all who entered maintenance were doing so based on exposure to the same weight loss intervention. Happily, though, the investigators did not require successful weight loss (> 5%) for entry into the maintenance phase, which likely further contributed to the generalizability of their results. Another area where the run-in likely helped was with retention of subjects—94% of those randomized for maintenance contributed complete data at the end of the 12-month study period.
As acknowledged by the authors, this study also has some important limitations. As with most weight loss/diet interventions, the participants in this study were mostly female, and mostly non-Hispanic white, and thus a substantially less diverse population than is represented by patients with obesity in the US. Furthermore, although some aspects of the patient population did promote generalizability (recruitment from primary care, chronic illness burden), these patients were fairly highly educated, which may have impacted their adherence and results.
The use of subsidized portion-controlled meals in this study, while evidence-based, may have clouded the results somewhat. Perhaps the effect of both interventions would have been less pronounced had patients not been provided with subsidies to access these foods. In their discussion, the investigators acknowledge that the study lacked a comparison group with no access to portion-controlled foods and that, in a post-hoc analysis, greater use of these foods corresponded with better weight loss and weight loss maintenance among all participants.
Finally, although it was beyond the scope of this study, this trial does not provide any information about how weight loss medications in either the weight loss or maintenance phases might impact these types of interventions. Now that the FDA has approved a number of such medications for long-term use, it would be very helpful to have more information about how medications might be integrated into these types of strategies, for interested patients, as physicians could clearly play an integral role in the pharmacologic management of weight, alongside effective behavioral interventions.
Applications for Clinical Practice
Low-to-moderate intensity in-person and telephone-based visits during weight maintenance may help to protect against weight regain, and could realistically be an option for many primary care practices and their patients. However, aside from Medicare patients, for whom monthly primary care–based weight maintenance visits are now covered, physicians would need to understand how to code and bill such visits appropriately in order to avoid having patients face unexpected charges.
—Kristina Lewis, MD, MPH