Table 3 Estimated coefficient (beta) and 95% confidence intervals (95% CI) of HOMA-IR in US adults during 2015–2016 for each quartile increase in blood cobalt levels stratified by different covariates
HOMA-IR | Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 | P for trend |
|---|---|---|---|---|---|
All | 0.038 (− 0.009, 0.084) | 0.045 (− 0.004, 0.094) | 0.03 (− 0.036, 0.061) | Reference | 0.095 |
Age (years) | |||||
 < 60 | 0.073 (0.007, 0.139) | 0.056 (− 0.013, 0.125) | 0.022 (− 0.048, 0.093) | Reference | 0.016 |
 ≥ 60 | − 0.017 (− 0.083, 0.049) | 0.030 (− 0.041, 0.101) | − 0.006 (− 0.073, 0.061) | Reference | 0.696 |
Gender | |||||
 Male | 0.020 (− 0.056, 0.096) | 0.032 (− 0.049, 0.113) | 0.061 (− 0.024, 0.146) | Reference | 0.732 |
 Female | 0.062 (0.001, 0.123) | 0.061 (− 0.003, 0.126) | − 0.016 (− 0.074, 0.043) | Reference | 0.037 |
Ethnicity | |||||
 Mexican American | 0.047 (− 0.063, 0.158) | − 0.026 (− 0.143, 0.091) | − 0.030 (− 0.145, 0.086) | Reference | 0.779 |
 Other Hispanic | 0.062 (− 0.064, 0.188) | 0.082 (− 0.040, 0.204) | 0.057 (− 0.071, 0.185) | Reference | 0.853 |
 Non-Hispanic White | 0.017 (− 0.053, 0.087) | 0.050 (− 0.026, 0.125) | − 0.005 (− 0.074, 0.065) | Reference | 0.279 |
 Non-Hispanic Black | 0.071 (− 0.050, 0.192) | 0.083 (− 0.045, 0.211) | 0.055 (− 0.087, 0.198) | Reference | 0.146 |
 Other race—including multiracial | 0.049 (− 0.089, 0.187) | 0.040 (− 0.110, 0.191) | 0.021 (− 0.119, 0.160) | Reference | 0.372 |
PIR | |||||
 < 1 | − 0.035 (− 0.145, 0.075) | − 0.004 (− 0.119, 0.112) | − 0.023 (− 0.127, 0.082) | Reference | 0.452 |
 ≥ 1 | 0.055 (0.004, 0.106) | 0.057 (0.003, 0.112) | 0.020 (− 0.035, 0.074) | Reference | 0.015 |
Alcohol use | |||||
 Yes | 0.032 (− 0.024, 0.089) | 0.064 (0.003, 0.124) | 0.038 (− 0.023, 0.099) | Reference | 0.094 |
 No | 0.076 (− 0.007, 0.158) | 0.016 (− 0.068, 0.101) | − 0.019 (− 0.099, 0.061) | Reference | 0.382 |
BMI (kg/m2) | |||||
 < 25 | 0.090 (− 0.003, 0.183) | 0.080 (− 0.018, 0.178) | 0.097 (0.008, 0.186) | Reference | 0.175 |
 25–30 | 0.014 (− 0.058, 0.085) | 0.063 (− 0.010, 0.135) | 0.021 (− 0.053, 0.095) | Reference | 0.177 |
 > 30 | 0.029 (− 0.049, 0.107) | 0.011 (− 0.075, 0.097) | − 0.059 (− 0.145, 0.028) | Reference | 0.610 |
Education level | |||||
 Less than 9th grade | 0.127 (− 0.004, 0.257) | 0.041 (− 0.093, 0.174) | 0.056 (− 0.074, 0.186) | Reference | 0.205 |
 9th–11th grade | 0.102 (− 0.048, 0.252) | 0.163 (− 0.001, 0.326) | 0.129 (− 0.024, 0.283) | Reference | 0.117 |
 High school graduate/GED or equivalent | 0.041 (− 0.065, 0.148) | 0.013 (− 0.094, 0.120) | 0.029 (− 0.076, 0.135) | Reference | 0.710 |
 Some college or AA degree | 0.039 (− 0.046, 0.123) | 0.073 (− 0.023, 0.168) | − 0.006 (− 0.097, 0.084) | Reference | 0.386 |
 College graduate or above | − 0.019 (− 0.099, 0.060) | 0.017 (− 0.067, 0.101) | − 0.027 (− 0.116, 0.061) | Reference | 0.718 |