Table 3.

Summary of Metabolomic Features Differing by Meal Challenge and CMD Status^a

Differing features (#)	Meal Challenge		Any CMD
LC-FT-MS columns	C18	HILIC	C18	HILIC
nb,c	349	343	349	343
Feature selection
Stage 1: Overall linear regressiond
q < 0.05 e	1288	802	---	---
Stage 2A: Stratified linear regressionf,g
CMDs subgroupg
q < 0.05e	---	---	1063	693
No CMDs subgroupg
q < 0.05e	---	---	875	508
Stage 2B: Overall linear regressiong,h
Interaction term (subgroup × time)g
P < 0.05e	---	---	60	48
q < 0.05	---	---	0	0
Annotations	Stage 1		Stage 2B
Annotated features	634	546	27	32
Total annotations	3406	5238	153	281

Abbreviations: CMD, cardiometabolic disease; FDR, false discovery rate; HILIC, hydrophilic interaction liquid chromatography; LC-FT-MS, liquid chromatography–Fourier transform mass spectrometry.

^aValues in this table indicate the number of features with log₂-normalized peak areas, which differed by the key subgroups of interest (meal challenge, any CMDs).

^bThe total features observed were 9849 (C18) and 13 908 (HILIC). After data filtering, 5085 (C18) and 7444 (HILIC) features remained eligible for the feature selection approach. A complete case approach was utilized in multivariable regressions.

^cAll regressions with C18 data were available among 349 participants with 2 samples (fasting, postprandial) of metabolomic data and key variables of interest (utilized to define CMDs). HILIC regressions were among 343 participants, based on data availability of key variables.

^d Stage 1 feature selection was based on multivariable regressions. For each feature, a linear model with repeated measurements was utilized (Proc Mixed in SAS); the model equation was: Y (log₂-normalized feature peak area)_i,j,t = β _0i,j,t + β ₁X₁ (timepoint [postprandial, baseline]) _i,j,t + β ₂X₂ (age at study visit)_i + β ₃X₃ (sex)_i, where each study participant was denoted as _i, feature was _j, and timepoint was _t. Features remained eligible for Stage 2 feature selection if the beta-coefficient of the meal challenge timepoint (β ₁) had FDR-adjusted P-value (q) < 0.05.

^e These features were subsequently eligible for visualizations, annotations, and pathway analysis.

^f Stage 2A feature selection utilized the same regression equation as in Stage 1, except these sets of regressions were stratified by CMD status (any versus none). In each subgroup, the total number of features with q < 0.05 of the beta-coefficient (β ₁) of the meal challenge timepoint are included in this table.

^g Among 1288 C18 features, or among 802 HILIC features

^h Among features eligible from Stage 1 selection, these were also considered with multivariable regressions that additionally considered subgroups of interest and their interaction terms with meal challenge as independent variables (Stage 2B). A linear model with repeated measurements was utilized (Proc Mixed in SAS); the model equation was: Y (log₂-normalized feature peak area)_i,j,t = β _0i,j,t + β ₁X₁ (timepoint [postprandial challenge, baseline]) _i,j,t + β ₂X₂ (any CMDs)_i + β ₃X₃ (age at study visit)_i + β ₄X₄ (sex)_i, + β ₅X₅ (anyCMDs*timepoint)_i where each study participant was denoted as _i, feature was _j, and timepoint was _t. The number of features with P < 0.05 and q < 0.05 the beta-coefficient (β ₅) of the interaction term were included in this table.