Study design and participants

To determine the relationship between weight loss ILI (compared to DSE) and CAD events among each Hp phenotype group separately, a reanalysis of data from the Look AHEAD study with additional Hp phenotype measurements was performed. The design, methods, and primary results of the Look AHEAD study (ClinicalTrials.gov identifier: NCT00017953) have been previously reported. [4, 5]. Briefly, from August 2001 to April 2004, 5,145 patients with type 2 diabetes were recruited. Participants were between 45 and 75 years of age and had a body mass index (BMI) of 25 kg/m2.² or higher (27 or higher for participants taking insulin), glycated hemoglobin (HbA)_1c) 11% or less, systolic blood pressure < 160 mmHg, diastolic blood pressure < 100 mmHg, triglyceride levels < 600 mg/dL, ability to complete a valid maximal exercise test, and established relationship with exercise capacity primary care provider .Participants were included with or without a history of cardiovascular disease. [4, 5]. Participants will either undergo ILI (focusing on reducing caloric intake and increasing physical activity, with the aim of achieving and maintaining at least 7% weight loss) or DSE over a median follow-up of 9.6 years randomly assigned to one of the following. The ILI included group and individual counseling sessions, which occurred weekly for the first 6 months and decreased in frequency during the study period. Specific intervention strategies include a calorie target of 1200 to 1800 kcal per day (less than 30% calories from fat and 15% or more calories from protein), use of meal replacement products, and Intense physical activity was included. Week by week. A toolbox of strategies was provided for participants who were having difficulty achieving their weight loss goals. DSE included three group sessions per year focused on diet, exercise, and social support from year 1 until his fourth year, and annually thereafter.Each participating center has ethical approval and all participants have provided written informed consent [4, 5].

Phenotypic analysis of haptoglobin

Hp phenotyping was performed using a validated high-throughput enzyme-linked immunosorbent assay (ELISA) that can distinguish Hp2-2 proteins from non-Hp2-2 proteins. Sensitivity and specificity were 99% and 98.1%, respectively. [17]. ELISA identifies Hp phenotypes based on differences in Hp protein size/structure [17]. There is a 1:1 correspondence between Hp genotype and Hp phenotype. [18]. The Hp phenotype does not change over time. Therefore, blood samples from follow-up visits were used. Of the 5,145 Look AHEAD participants, serum samples were available for His-Her Hp phenotyping in 4,542 (88.3%). The remaining 603 participants were excluded because serum samples from these participants were not available due to sample depletion from other studies or consent restrictions.

result

Key outcomes for major CAD events were defined as a composite of the following pre-specified Look AHEAD outcomes: [4, 5]: Fatal and non-fatal myocardial infarction, hospitalization for angina pectoris, and fatal CAD (definite and probable).An independent adjudication committee reviewed all outcome events. [4]. Although the mechanism is not well understood, stroke is an endpoint that is associated with the Hp1-1 rather than the Hp2-2 phenotype. [19, 20]. Stroke is a complex of different stroke subtypes with different etiologies that are not necessarily related to atherosclerosis, and analysis by Hp phenotype needs to separate CAD and stroke from the composite CVD outcome suggests that there is. Therefore, in the current analysis, we focused on the primary outcome of CAD events rather than the composite primary outcome of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for angina in the original Look AHEAD study. researched.

Sensitivity analyzes compared ILI with other Looks, including the study’s primary composite outcome of CVD (cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or angina hospitalization), total mortality, and severity. The relationship with AHEAD outcomes was also investigated. Hypoglycemic events (loss of consciousness, seizure, or blood glucose level <70 mg/dL, which cannot be self-treated and requires the assistance of another person) (Additional file 1: Table S1).

statistical analysis

All analyzes were performed using STATA/SE software version 18 (StataCorp, College Station, TX). Due to the low frequency of the Hp1-1 phenotype, the Hp2-2 phenotypic variable is dichotomized to represent the Hp2-2 phenotype (yes/no), except when testing Hardy-Weinberg equilibrium (HWE). approach was used. Similar structure and function of Hp1-1 and Hp2-1 compared to Hp2-2 [8, 9, 16, 21, 22].

Participants were grouped based on a combination of treatment assignment and Hp phenotype, and baseline characteristics were summarized using t-tests or Kruskal-Wallis tests for continuous variables and x.² Testing for categorical variables.

The goal of the current analysis was to replicate the original Look AHEAD study. [4] Analyze as closely as possible within each phenotypic group. Therefore, we evaluated the effect of the intervention on incident CAD using cause-specific Cox proportional hazards regression models, as recommended for etiological regression analysis even when there are competing risks. [23, 24]. We assessed the effect of changing this association by haptoglobin phenotype by including an interaction term between intervention group and Hp phenotype and stratifying results by Hp phenotype. did. Multivariable models were adjusted not only for traditional risk factors but also for other variables that differed between treatment groups at baseline. The frequency of the Hp2-2 phenotype varies by racial and geographic population. [10] Therefore, race/ethnicity was also identified as an important variable to include in the model. As such, the models included age, gender, study site, past CVD, race/ethnicity (modeled for all participants), triglycerides, systolic blood pressure, diastolic blood pressure, income (with missing categories), and education. , adjusted for diabetes medications. use, antihypertensive drug use, lipid treatment drug use, and antidepressant drug use.

We identified a priori subgroups for stratification in the primary analysis of this study.Current reporting guidelines recommend disaggregating results by gender [25]and the distribution of Hp phenotype frequencies differs on an ethnic basis and among geographic populations. [10]. Current diabetes treatment guidelines suggest that diabetes duration and established CVD are important factors in glycemic control. [26]Therefore, stratified analyzes by race/ethnicity, gender, previous CVD at baseline, diabetes duration (>10 years), and use of diabetes medications at baseline were performed separately for each phenotypic group. Ta. For racial/ethnic stratification, we were able to run models adjusted only for the following racial/ethnic groups that had sufficient numbers for valid estimates and ensured anonymity: Whites ( 67%), Black (17%), and Hispanic (13%). Test for interactions between ILI and race/ethnicity, gender, her CVD history at baseline, diabetes duration, and diabetes medication use by adding interaction terms to the model for each phenotype group Did.

On September 14, 2012, based on unhelpful analysis and recommendations from the Data and Safety Monitoring Board, the Look AHEAD intervention was suspended and all data were censored as of that date. [4]. Follow-up time for the current analysis was defined as the time from the date of randomization to the date of documented outcome or until the participant was censored if no event occurred. A Bonferroni-corrected significance level was applied to account for multiple testing. P< 0.002 (0.05 divided by 24). Sensitivity analyzes used inverse probability weighting to assess the impact on potential selection bias of excluding individuals with missing her Hp phenotype data from all enrolled participants (11.7%) Did. [27]. In another sensitivity analysis, we limited follow-up to 1, 3, and 5 years.