Partial remission of type 2 diabetes mellitus included no use of antidiabetics, hemoglobin A1c level of less than 6.5% (to convert to proportion of total hemoglobin, multiply by 0.01), and fasting plasma glucose level of 125 mg/dL or less (to convert to millimoles per liter, multiply by 0.0555). Complete remission of type 2 diabetes mellitus included no use of antidiabetics, hemoglobin A1c level of less than 5.7%, and fasting plasma glucose level of 100 mg/dL or less. Missing data at follow-up were assumed to be no remission. The test of the difference between treatment group P values are calculated for each point as follows: year 1, P < .001; year 2, P < .001; and year 3, P = .004. LAGB indicates laparoscopic adjustable gastric banding; LWLI, lifestyle weight loss intervention (intensive); and RYGB, Roux-en-Y gastric bypass.
LAGB indicates laparoscopic adjustable gastric banding; LWLI, lifestyle weight loss intervention (intensive); and RYGB, Roux-en-Y gastric bypass. The bars indicate standard errors. To convert FPG to millimoles per liter, multiply by 0.0555; and HbA1c to proportion of total hemoglobin, multiply by 0.01.
A, Baseline, n = 20; year 1, n=18; year 2, n = 18; and year 3, n = 18. B, Baseline, n = 21; year 1, n = 19; year 2, n = 17; and year 3, n = 20. C, Baseline, n = 20; year 1, n = 14; year 2, n = 14; and year 3, n = 14 (1 participant was missing data). LAGB indicates laparoscopic adjustable gastric banding; LWLI, lifestyle weight loss intervention (intensive); and RYGB, Roux-en-Y gastric bypass.
Modeled data and the bars indicate standard errors. LAGB indicates laparoscopic adjustable gastric banding; LWLI, lifestyle weight loss intervention (intensive); and RYGB, Roux-en-Y gastric bypass.
eTable 1. Baseline Sample Characteristics
eTable 2. Complications at 3 Years
Courcoulas AP, Belle SH, Neiberg RH, Pierson SK, Eagleton JK, Kalarchian MA, DeLany JP, Lang W, Jakicic JM. Three-Year Outcomes of Bariatric Surgery vs Lifestyle Intervention for Type 2 Diabetes Mellitus TreatmentA Randomized Clinical Trial. JAMA Surg. 2015;150(10):931-940. doi:10.1001/jamasurg.2015.1534
Copyright 2015 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.
Questions remain about the role and durability of bariatric surgery for type 2 diabetes mellitus (T2DM).
To compare the remission of T2DM following surgical and nonsurgical treatments.
Design, Setting, and Participants
In this 3-arm randomized clinical trial conducted at the University of Pittsburgh Medical Center from October 1, 2009, to June 26, 2014, in Pittsburgh, Pennsylvania, outcomes were assessed 3 years after treating 61 obese participants aged 25 to 55 years with T2DM. Analysis was conducted with an intent-to-treat population.
Participants were randomized to either an intensive lifestyle weight loss intervention for 1 year followed by a low-level lifestyle intervention for 2 years or surgical treatments (Roux-en-Y gastric bypass [RYGB] or laparoscopic adjustable gastric banding [LAGB]) followed by low-level lifestyle intervention in years 2 and 3.
Main Outcomes and Measures
Primary end points were partial and complete T2DM remission and secondary end points included diabetes medications and weight change.
Body mass index (calculated as weight in kilograms divided by height in meters squared) was less than 35 for 26 participants (43%), 50 (82%) were women, and 13 (21%) were African American. Mean (SD) values were 100.5 (13.7) kg for weight, 47.3 (6.6) years for age, 7.8% (1.9%) for hemoglobin A1c level, and 171.3 (72.5) mg/dL for fasting plasma glucose level. Partial or complete T2DM remission was achieved by 40% (n = 8) of RYGB, 29% (n = 6) of LAGB, and no intensive lifestyle weight loss intervention participants (P = .004). The use of diabetes medications was reduced more in the surgical groups than the lifestyle intervention–alone group, with 65% of RYGB, 33% of LAGB, and none of the intensive lifestyle weight loss intervention participants going from using insulin or oral medication at baseline to no medication at year 3 (P < .001). Mean (SE) reductions in percentage of body weight at 3 years were the greatest after RYGB at 25.0% (2.0%), followed by LAGB at 15.0% (2.0%) and lifestyle treatment at 5.7% (2.4%) (P < .01).
Conclusions and Relevance
Among obese participants with T2DM, bariatric surgery with 2 years of an adjunctive low-level lifestyle intervention resulted in more disease remission than did lifestyle intervention alone.
clinicaltrials.gov Identifier: NCT01047735
It remains to be established whether bariatric surgery is a durable and effective treatment for type 2 diabetes (T2DM) and how bariatric surgery compares with intensive lifestyle modification and medication management with respect to T2DM-related outcomes. Nonsurgical treatments alone have not generally resulted in the complete amelioration of diabetes mellitus or its potential long-term complications.1 As demonstrated in many observational studies2- 5 and several small randomized clinical trials (RCTs) of short duration,6- 9 T2DM is greatly improved after bariatric surgery. To our knowledge, only 1 reported RCT with at least 3 years of follow-up to date has shown that bariatric surgery (gastric sleeve or gastric bypass) was superior to intensive medical therapy for glycemic control, medication use, and quality-of-life measures.9 Thus, more information is needed about the longer-term effectiveness and risks of all types of bariatric surgical procedures compared with lifestyle and medical management for those with T2DM and obesity. In addition, little is known about the relative utility of surgical vs nonsurgical treatments for those with lower body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) between 30 and 35 (class I obesity) who are typically not included in surgical studies that are intended for weight loss outcomes alone.10
Earlier results from the trial reported here highlighted the significant challenges to completing a larger and more definitive RCT to determine the best treatment for T2DM in the setting of obesity. Quiz Ref IDThe 1-year results from this trial showed that gastric bypass was the most effective treatment, followed by gastric banding for both T2DM remission and weight loss.11 In this longer-term study, we report 3-year results examining the efficacy of 2 types of bariatric surgery (Roux-en-Y gastric bypass [RYGB] and laparoscopic adjustable gastric banding [LAGB]) and an intensive lifestyle weight loss intervention (LWLI) for 1 year, followed by a low-level lifestyle intervention (LLLI) for all 3 treatment groups in years 2 and 3 that was modeled after the Look AHEAD (Action for Health in Diabetes) Trial.12 This report addresses the primary question of comparative efficacy of surgical and nonsurgical treatments for T2DM remission and reports other glycemic control outcomes, weight change, lipids, blood pressure, and body composition. These results contribute to addressing questions about the relative efficacy of different surgical vs nonsurgical treatments for T2DM in lower BMI individuals.
The rationale, design, and methods of this study, including details on recruitment, inclusion, assessment, randomization, and intervention during the first year of follow-up, have been reported.11 Briefly, the trial was a 3-arm RCT stratified by sex and baseline BMI, conducted at an academic medical center, that compared the efficacy for treating T2DM of 2 common surgical procedures (RYGB and LAGB) plus LLLI in years 2 and 3 of follow-up with intensive LWLI in year 1 followed by 2 years of LLLI. Adults aged 25 to 55 years with a BMI of 30 to 40 were eligible and the diagnosis of T2DM was confirmed by fasting plasma glucose (FPG) level of greater than 125 mg/dL (to convert to millimoles per liter, multiply by 0.0555) and/or treatment with glucose-lowering medications.11 The 61 individuals who were treated (20 with RYGB, 21 with LAGB, and 20 with LWLI)11 were eligible for the second phase of the trial and are included in analyses reported here (Figure 1). The study protocol was reviewed and approved by the Institutional Review Board at the University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania. The trial protocol can be found in Supplement 1.
On completing 1-year follow-up, participants provided written informed consent to participate for 2 more years with annual visits and the addition of structured LLLI for all 3 treatment groups (RYGB + LLLI, LAGB + LLLI, and LWLI + LLLI). Both the initial intensive (LWLI) and later low-level (LLLI) lifestyle interventions were modeled after the Diabetes Prevention Program and Look AHEAD and adapted for postsurgical participants. An initial instructional group session was held for participants in both surgical arms (RYGB and LAGB) to provide a lesson on behavioral weight control and orient them to the skills and strategies that had been learned and developed for the LWLI group in year 1. Quiz Ref IDThe LLLI for all 3 treatment groups consisted of twice-monthly contact (1 in-person session [approximately 30-45 minutes] and 1 brief [<10 minutes] telephone contact) and regular refresher group series.13,14 Each intervention contact focused on a specific behavioral topic related to weight loss. If an individual missed an in-person session, all intervention materials were mailed to the participant. If a participant became unable to attend monthly in-person LLLI sessions, they received intervention telephone calls in place of visits. The T2DM management was carried out by the original treating endocrinologist, with glucose values monitored by the study physician for safety.
The primary outcomes were measures of T2DM remission, partial and complete according to American Diabetes Association criteria.11,15Quiz Ref IDPartial remission of T2DM was defined as the absence of any medications for diabetes mellitus, with glycated hemoglobin A1c (HbA1c) level less than 6.5% (to convert to proportion of total hemoglobin, multiply by 0.01) and FPG level less than or equal to 125 mg/dL, and complete remission of T2DM defined as the absence of medications with HbA1c level less than 5.7% and FPG less than or equal to 100 mg/dL.15 At baseline prior to treatment, and annually through 36 months, changes in weight (difference in weight, percentage of weight loss from baseline, BMI, and waist circumference), glycemic control (change in FPG and HbA1c levels), and the use of glucose-lowering medications (categorized; none, insulin only, insulin/other medication, and oral/other medication) were assessed. Changes in lipid levels (total cholesterol, triglycerides, and high- and low-density lipoprotein cholesterol), blood pressure, and body composition (percentage of body fat, lean mass, and bone mass) were secondary outcomes. Body composition was assessed using dual-energy x-ray absorptiometry (GE Lunar Inc). Blood pressure level was measured twice and averaged at each annual visit.
Statistical analyses were performed using SAS version 9.3 (SAS Institute), with the type I error rate fixed at 0.05 (2-tailed). Categorical variables are summarized using frequencies and percentages. Continuous variables with normal distributions are presented as mean (SD); continuous variables with non-normal distributions are presented as medians and interquartile ranges. Differences in baseline characteristics among the RYGB, LAGB, and LWLI groups were examined using the Pearson χ2 test or Fisher exact test for categorical variables and analysis of variance or Kruskal-Wallis test for continuous variables.
Changes from baseline to 12, 24, and 36 months were analyzed using mixed-effects models with covariate adjustment for randomization stratification factors (sex and baseline BMI). Change in weight was adjusted for baseline weight. Inferences focused on the overall treatment effect, time, and treatment-by-time interaction. Pairwise comparisons were made between treatment groups at 36 months. Least-square means were obtained from the models along with their standard errors. Intent-to-treat analyses were conducted using multiple imputation implemented using SAS procedures PROC MI and PROC MIANALYZE. For each outcome, 10 data sets were imputed and results were combined. For categorical data with missing values (eg, T2DM remission and medication use), no remission or no improvement for the condition at follow-up was imputed. The Fisher exact test was used to compare differences between groups for T2DM remission and medication category use.
Of the 61 participants who underwent treatment, 52 (85% overall; 18 [90%] with RYGB, 20 [95%] with LAGB, and 14 [70%] with LWLI) were evaluated for the assessments of 3-year safety and efficacy. Of the 52 participants included in the 3-year analyses, 82% were women and 79% were white. The mean (SD) values were 47.3 (6.6) years for age, 35.7 (3.1)for BMI, and 100.5 (13.7) kg for baseline weight; 26 participants (43%) had class I obesity (BMI<35). The mean (SD) values were 7.8% (1.9%) for baseline HbA1c level, 171.3 (72.5) mg/dL for FPG level, and 6.5 (4.8) years for duration of T2DM. Higher percentages of individuals in the RYGB group had insulin requirements at baseline (RYGB, 50%; LAGB, 38%; and LWLI 30%; P = .01) and the RYGB group had a significantly higher baseline HbA1c level than LWLI (mean [SD]: RYGB, 8.6% [2.1%]; LAGB, 7.9% [2.2%]; and LWLI, 7.0% [0.8%]; overall P = .03; RYGB vs LWLI P = .01) (eTable 1 in Supplement 2).
Quiz Ref IDAt 3 years, any T2DM remission (partial or complete) was achieved in 40% (n = 8) of RYGB, 29% (n = 6) of LAGB, and no LWLI (P = .004) participants (Figure 2), while complete remission was achieved in 15% (n = 3) of RYGB, 5% (n = 1) of LAGB, and no LWLI group participants (P = .21). Continuous, sustained (any; partial or complete) remission for at least 2 consecutive years of the 3-year follow-up period was observed in 45% (n = 9) of RYGB and 29% (n = 6) of LAGB patients. As shown in Figure 2, there was a decline in any remission among RYGB participants from 60% at year 1 to 45% at year 2 and 40% at year 3, whereas any remission for LAGB participants remained stable at 29% and none for LWLI over the 3-year period (P = .09).
After 3 years, each of the surgical procedures plus LLLI was superior to lifestyle intervention alone (LWLI + LLLI) in achieving glycemic control (Figure 3). The RYGB group had the greatest change in both HbA1c (mean [SD], −1.42% [0.34%]) and FPG (−66.0 [10.94] mg/dL) levels from baseline to 3 years (HbA1c level, P < .0013 for RYGB vs LWLI; FPG, P < .05 for RYGB vs both LAGB and LWLI) (Table). The LAGB group showed improved HbA1c levels, averaging −0.80% (0.32%) at 3 years (P = .04 for LAGB vs LWLI) and FPG levels improved a mean (SD) of −35.2 (10.47) mg/dL (P = .67). Also examined were the changes in HbA1c and FPG levels over time by class (I and II) of obesity. For both measures, there were no significant interactions between obesity class and treatment groups, indicating that the patterns over time between treatment groups did not differ significantly by class of obesity. Quiz Ref IDThe use of diabetes medications was reduced more in the surgical groups than the lifestyle-alone group; with 65% of RYGB, 33% of LAGB, and 0% of LWLI participants going from using insulin or oral medication at baseline to no medication at year 3 (P < .001). Therefore, at 3 years, those in the RYGB group had the largest percentage of individuals (72%) not requiring any medications for T2DM compared with those in the LAGB (45%) and LWLI (0%) groups (Figure 4, P < .001).
At 3 years, modeled reductions in body weight, BMI, and waist circumference were greater after RYGB and LAGB than after lifestyle treatment alone (Table). The percentage of reduction in body weight was also greater after RYGB than after LAGB (P = .0002). Figure 5 shows the modeled mean (SE) percentage of weight change from baseline to each of 3 follow-up points by treatment group: RYGB, 29.1% (1.6%) at year 1 to 25.0% (2.0%) at year 3; LAGB, 18.5% (1.7%) at year 1 to 15.0% (2.0%) at year 3; and LWLI, 7.6% (1.9%) at year 1 to 5.7% (2.4%) at year 3.
Modeled change in body composition is shown in the Table. The mean (SE) change in percentage of body fat at 3-year follow-up was significantly greater in RYGB compared with both LABG and LWLI participants (−10.7% [1.25], −5.63% [1.19%], and −3.08% [1.44%], respectively; both pairwise P < .01). The change in mean (SE) kilograms of lean mass from baseline to year 3 was significantly less in the LWLI (−0.62 [0.99]) compared with the LAGB (−2.78 [0.79]; P = .04) and RYGB (−5.58 [0.81]; P < .001) groups, and in the LAGB compared with the RYGB (P = .004) groups. There was also a different pattern in mean bone mass over time between the groups (P = .0004), showing the reduction in bone mass from baseline to year 3 to be greater in the RYGB compared with both the LAGB (P = .0003) and LWLI (P < .001) groups.
At 3 years, the RYGB surgical group experienced greater improvements in triglyceride levels (P = .003) and high-density lipoprotein cholesterol levels (P = .0004) compared with the lifestyle arm (Table). Improvements in systolic and diastolic blood pressure levels were less consistent; however, the RYGB group had the greatest improvements in systolic blood pressure compared with the LAGB and LWLI groups (P < .05 for both; Table) and diastolic blood pressure from baseline to year 3 compared with the LAGB group (P = .0005).
There were no complications reported in the LWLI group at any point up to 3 years and no additional surgical interventions in either of the 2 surgical groups after year 1 of follow-up.11 One infusion port replacement for malposition in an LAGB participant occurred during the first year of follow-up. There were no LAGB removals or replacements. All adverse events and complications are shown in eTable 2 in Supplement 2.
The results of this study show that RYGB + LLLI and LAGB+LLLI are superior to lifestyle treatment alone for T2DM remission and other glycemic control end points at 3 years. One important aspect of this study was that more than 40% of the sample were individuals with class I obesity (BMI of 30 to <35) for whom data in the literature are largely lacking.10 Those who underwent a surgical procedure followed by LLLI were significantly more likely to achieve and maintain glycemic control than were those who received intensive and then maintenance (low-level) lifestyle therapy alone, regardless of obesity class. More than two-thirds of those in the RYGB group and nearly half of the LAGB group did not require any medications for T2DM treatment at 3 years. Analysis of secondary end points also showed favorable results for the RYGB group and to a lesser extent for the LAGB group. Significant reductions in lean and bone mass were observed in the RYGB group that may warrant further investigation. Adverse events were uncommon after the first year. Thus, these results add to a growing body of literature suggesting that bariatric surgery may be a viable treatment option for people with BMI of 30 to 40 for whom medical management is ineffective.
A systematic review and meta-analysis focused on nonmorbidly obese people found only 3 trials, including individuals with BMIs between 30 and 40, and in total, they included only 13 people with BMI less than 35. This review demonstrated that surgery was associated with greater weight loss (range, 14.4-24 kg) and glycemic control (range, 0.9%-1.43% improvements in HbA1c levels) during 1 to 2 years of follow-up compared with nonsurgical treatment.10 Further, they concluded that evidence is insufficient to reach conclusions about the appropriate use of bariatric surgery in this lower-BMI (BMI, 30-35; class 1 obesity) population until more data are available about both complications and long-term outcomes of surgery. This report helps fill this gap by contributing 26 additional low-BMI participants undergoing surgical and nonsurgical treatments to the literature for diabetes remission and weight outcomes. Another systematic review and meta-analysis showed that bariatric surgery, when compared with nonsurgical treatment, leads to greater body weight loss and higher remission rates of T2DM and metabolic syndrome.16 However, these results are limited mostly to 2 years of follow-up and are based on a relatively small number of studies and individuals. To our knowledge, the only longer-term RCT with 3-year follow-up compared RYGB or sleeve gastrectomy with intensive medication management vs an intensive medical management regimen alone in individuals with uncontrolled T2DM.9 It demonstrated 38% of RYGB, 24% of sleeve gastrectomy, and 5% of intensive medical treatment groups achieved an HbA1c level less than 6.0% either while taking or not taking glycemic control medications.
Results of the trial reported here add important data to these longer-term results by showing a comparable 40% partial or complete remission of T2DM (including the requirement to not be taking any medications to meet the remission definition) with RYGB and 29% remission after LAGB, which is a new result. To our knowledge, there has not been any other RCT with 3-year results that include the LAGB as a surgical treatment alternative. The LAGB is a less-invasive, reversible, and low-risk procedure that may have a role for treatment, especially in the lower-BMI group. Several small RCTs comparing LAGB with lifestyle therapy alone in people with BMIs of 30 to 40 have shown superior weight loss and diabetes or metabolic syndrome improvement in the LAGB arm but did not report beyond 2 years of follow-up.6,16,17 In 2 of these prior studies of adults, the lifestyle intervention varied from standard diabetes care6 to the use of very low-calorie diets,17 resulting in mean percentages of baseline weight loss of 1.7% and 5.7%, respectively, at 2 years in the nonsurgical arms of each trial and 20% mean weight lost 2 years following the LAGB in both trials. There was remission (HbA1c <6.2%, FPG <126, and not taking any medications) of T2DM in 22 (73%) in the surgical group and 4 (13%) of the usual care group in 1 study.6 In the other trial, the prevalence of metabolic syndrome was reduced significantly in the surgical group at the completion of the 2-year study.17 In the current study, the remission rate of T2DM was lower (29%) in the band treatment arm than in these 2 previously published trials and may reflect differences in study groups at baseline, remission definition differences, or the heterogeneity of response to treatment in those participating in each of these trials. Nevertheless, the mean weight loss (15%) and remission rate for T2DM (29%) in the band arm of this trial were similar to that in the 3-year Longitudinal Assessment of Bariatric Surgery Study.18 The Longitudinal Assessment of Bariatric Surgery Study was an observational multicenter study that did not standardize postsurgical care, showed significant heterogeneity of weight loss response, and may be more representative of LAGB results in the United States.
This current study had several strengths that included the delivery of a standardized nonsurgical treatment that was intensive in the first year and lower level in subsequent years modeled after the Diabetes Prevention Program and the Look AHEAD studies.12,13,19,20 Another strength of this trial was the broad inclusion criteria for T2DM, which resulted in recruiting some participants with less disease severity than those recruited into similar RCTs targeting only those with uncontrolled T2DM.7,21,22 Thus, these results may generalize to the broader population of those with obesity and T2DM of varying severity. Further, to our knowledge, this trial is the first in the United States to generate 3-year results for LAGB, an inherently less-invasive procedure that may be of particular interest for patients with obesity but in a lower range of BMI (30-35). The limitations of this study included the small sample size from a single site, which may affect generalizability. Nevertheless, a larger and even more definitive study will likely not be completed in the future owing to numerous research challenges that have been identified. These include large numbers of potential participants being screened to successfully randomize participants, the need for a multicenter consortium for results to be generalizable, and the ensuing prohibitive costs.11,23,24 A National Institutes of Health 2013 workshop summary concluded that important information about this topic may need to come, in the future, from either combining similar smaller trials or from carefully controlled observational studies.23 Therefore, the data from this relatively small trial are valuable and worthy of careful consideration alone and/or in combination with other RCTs with similar aims and goals.9,21
This study provides further important evidence that at longer-term follow-up of 3 years, surgical treatments, including RYGB and LAGB, are superior to lifestyle intervention alone for the remission of T2DM in obese individuals including those with a BMI between30 and 35. While this trial provides valuable insights, unanswered questions remain such as the impact of these treatments on long-term microvascular and macrovascular complications and the precise mechanisms by which bariatric surgical procedures induce their effects.
Corresponding Author: Anita P. Courcoulas, MD, MPH, Department of Surgery, University of Pittsburgh Medical Center, 3380 Blvd of the Allies, Ste 390, Pittsburgh, PA 15213 (firstname.lastname@example.org).
Accepted for Publication: May 6, 2015.
Published Online: July 1, 2015. doi:10.1001/jamasurg.2015.1534.
Author Contributions: Dr Courcoulas had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Courcoulas, Belle, Eagleton, Jakicic.
Acquisition, analysis, or interpretation of data: Courcoulas, Neiberg, Pierson, Eagleton, Kalarchian, DeLany, Lang, Jakicic.
Drafting of the manuscript: Courcoulas, Neiberg, Pierson, Lang, Jakicic.
Critical revision of the manuscript for important intellectual content: Belle, Neiberg, Pierson, Eagleton, Kalarchian, DeLany, Lang, Jakicic.
Statistical analysis: Belle, Neiberg, Pierson, Lang.
Obtained funding: Courcoulas, Eagleton, Jakicic.
Administrative, technical, or material support: Courcoulas, Pierson, Eagleton, Jakicic.
Study supervision: Courcoulas, Pierson, Eagleton, Kalarchian, DeLany, Jakicic.
Conflict of Interest Disclosures: Dr Courcoulas has grants from Nutrisystem, J&J Ethicon, and Covidien, and she is a project consultant for Ethicon and Apollo Endosurgery. Dr Kalarchian has grants from the Obesity Society/Nutrisystem. Dr Jakicic has grants from Jawbone/BodyMedia and personal fees from Weight Watchers (outside of this work). No other disclosures were reported.
Funding/Support: The study was funded by National Institutes of Health (NIH)–National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) grant R01DK095128 and by Magee-Womens Hospital of UPMC (University of Pittsburgh Medical Center) for subsidizing the surgical procedures. Drs Courcoulas, Jakicic, and Kalarchian have support from the NIH and NIDDK for this work. Dr Kalarchian also has grants from the ASMBS Foundation and grants from NIDDK (outside of this work). Dr Courcoulas has grants from NIDDK (outside of this work).
Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.