Introduction
Obesity and overweight are significant public health concerns, often co-occurring with conditions like hypertension and type 2 diabetes. Effective weight management programs are crucial for individuals with these comorbidities. This article examines the statistical significance of different weight loss interventions, focusing on a study that evaluated the effectiveness of an online program alone versus a combined approach incorporating population health management.
Study Design and Participants
A cluster randomized trial was conducted across 15 primary care practices in the US. The study enrolled 840 participants between July 19, 2016, and August 10, 2017. Eligible participants were aged 20 to 70 years, had a scheduled primary care visit, a body mass index (BMI) between 27 and less than 40, and a diagnosis of hypertension or type 2 diabetes. Participants were excluded if they had undergone or were planning to undergo bariatric surgery, had weight loss of 5% or greater of body weight within the past 6 months, were taking weight loss medications, or had contraindications for weight loss. The primary care practices were divided into 24 clinics based on preexisting administrative divisions and grouped into 3 strata: hospital-based clinics, community-based clinics, and community health centers. Randomization was stratified by clinic type to ensure balance across the 3 groups.
Participants were assigned to one of three groups:
- Usual Care Group: Received routine care as directed by their primary care physicians.
- Online Program Only Group: Registered for an evidence-based online weight management program.
- Combined Intervention Group: Received the online program plus additional support from a population health manager.
Intervention Components
Online Program
The online program, called BMIQ (Intellihealth Inc), was accessible via computer, tablet, or smartphone. It included both patient and professional interfaces. The patient interface featured:
- 33 nutrition and behavioral change educational sessions in written and video format, released weekly for the first 16 weeks and then every other week.
- Exchange-based meal plans and sample menus.
- Tools for tracking weight, food intake, and activity.
The professional interface included patient monitoring and alerts, progress notes, and reporting features.
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Population Health Management
Patients in the combined intervention group received the same online program components and extra support from a population health manager. The role of the population health managers was to monitor patients’ progress in the online program and to conduct outreach according to a specific protocol. The population health managers did monthly check-in calls with patients and they uploaded a patient summary report from the online program to the EHR every other month. During the monthly calls, the population health managers reviewed patients’ progress, addressed questions, and encouraged patients to use the online program regularly. They also offered patients a second brief phone consultation with a registered dietitian approximately 6 months after enrollment. In some situations (eg, if a patient lost ≥7.5% of their body weight), the population health managers would enter a note in the EHR and send direct messages to patients and primary care physicians in case this affected decisions related to care.
Data Collection and Outcomes
Data on demographic and clinical factors, including measured weight and BMI, were extracted from the electronic health record (EHR) at enrollment and at approximately 6, 12, and 18 months after enrollment. Patients in all 3 groups also completed surveys at baseline and at 6, 12, and 18 months after enrollment to assess patient-reported outcomes and satisfaction. The primary outcome was weight change at 12 months (±90 days) after enrollment, calculated as the difference (in kilograms) between each patient’s measured weight at the initial visit and at the visit approximately 12 months later.
Statistical Analysis
Participants were analyzed according to randomization group and all participants were included. Repeated-measures mixed-effects linear regression was used using weights at baseline and at 12 months (because the primary outcome was weight change at 12 months) first and then using weights at baseline and at 6, 12, and 18 months. Indicators for group and time along with interaction terms were included to demonstrate the intervention effect. The prespecified covariates (including age, sex, race/ethnicity, educational level, and medical conditions) that could affect weight change were adjusted for. Clinic type was included as a fixed effect and clinic, physician, and patient were included as random effects. The same general modeling approach was used to compare changes in continuous secondary outcomes across the 3 groups. For binary outcomes (eg, weight loss ≥5%, excellent or very good health status), mixed-effects logistic regression was used.
Results
Participant Characteristics
At baseline, the mean age of the participants was 59.3 years (SD, 8.6 years), the mean weight was 92.1 kg (101.9 kg for males and 85.6 kg for females), the mean BMI was 32.5 (including both males and females), 60% of participants were female, and 76.8% were White.
Weight Change at 12 Months
There was a significant difference in weight change at 12 months by group. The mean weight change was -1.2 kg (95% CI, -2.1 to -0.3 kg) in the usual care group, -1.9 kg (95% CI, -2.6 to -1.1 kg) in the online program only group, and -3.1 kg (95% CI, -3.7 to -2.5 kg) in the combined intervention group (P < .001). The difference in weight change between the combined intervention group and the usual care group was -1.9 kg (97.5% CI, -2.9 to -0.9 kg; P < .001), and the difference between the combined intervention group and the online program only group was -1.2 kg (95% CI, -2.2 to -0.3 kg; P = .01).
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Percentage Weight Change and Weight Loss of 5% or Greater
There was a significant difference in the percentage weight change at 12 months by group with mean weight change of -1.4% (95% CI, -2.3% to -0.6%) in the usual care group, -1.9% (95% CI, -2.8% to -1.0%) in the online program only group, and -3.0% (95% CI, -3.8% to -2.1%) in the combined intervention group (P < .001). There was a significant difference in the percentage of participants with weight loss of 5% or greater by group; 14.9% (95% CI, 10.2% to 19.6%) of participants in the usual care group, 20.8% (95% CI, 14.5% to 27.2%) of participants in the online program only group, and 32.3% (95% CI, 25.8% to 38.8%) of participants in the combined intervention group lost at least 5% of their body weight (P < .001).
Confidence in Ability to Lose Weight
There was a significant difference in change in confidence in the ability to lose weight by group with the mean change of -0.7 points (95% CI, -1.1 to -0.3 points) in the usual care group and -0.4 points (95% CI, -0.9 to 0.07 points) in the online program only group; however, the mean change was 0.5 points (95% CI, 0.06 to 0.9 points) in the combined intervention group (P < .001).
Weight Change at 18 Months
There were significant differences by group in weight change over 18 months. At 18 months, the mean weight change was -1.9 kg (95% CI, -2.8 to -1.0 kg) in the usual care group, -1.1 kg (95% CI, -2.0 to -0.3 kg) in the online program only group, and -2.8 kg (95% CI, -3.5 to -2.0 kg) in the combined intervention group (P < .001). The difference in weight change between the combined intervention group and the usual care group was -0.9 kg (95% CI, -1.9 to 0.2 kg; P = .10) and the difference between the combined intervention group and the online program only group was -1.6 kg (95% CI, -2.7 to -0.5 kg; P = .003).
Program Engagement
The use of the online program was not significantly different in the online program only group and the combined intervention group. The median number of log-ins over 12 months among participants in the online program only group was 25 and in the combined intervention group was 26 and the median number of sessions viewed was 5 in both groups. During the 12 months, the number of contacts with a research assistant or population health manager was much higher among participants in the combined intervention group than in the online program only group (median of 9 vs 3 contacts, respectively). The percentage of participants who had at least 1 consultation with a dietitian was 37.3% in the combined intervention group vs 28.7% in the online program only group.
Discussion
The cluster randomized trial demonstrated significant differences in weight change and other weight-related outcomes among primary care patients with overweight or obesity and a diagnosis of hypertension or type 2 diabetes. Participants in the combined intervention group experienced the greatest weight loss at 12 months, followed by the online program only group and the usual care group. At 18 months, significant differences in weight change persisted, although the difference between the combined intervention group and the usual care group was no longer significant.
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