Table 2.
Cox-regression for the joint association of elevated highly-sensitive cardiac troponin-T and low ankle-brachial index with cardiovascular events.
| Joint effects of exposures | End points |
|||||
|---|---|---|---|---|---|---|
| Participants | Events | Person-years | Incidence rate (100 person-years) | Unadjusted HR (95% CI) | Adjusted HR (95% CI) | |
| Outcome CHD | ||||||
| Non-elevated hs-cTnT (<14 ng/L) & normal ABI (0.9 – 1.4) | 9197 | 1144 | 117,564.3 | 0.97 | 1 (reference) | 1 (reference) |
| Elevated hs-cTnT (≥14 ng/L) & normal ABI (0.9 – 1.4) | 876 | 203 | 7433.1 | 2.73 | 2.98 (2.56, 3.46)§ | 1.65 (1.37, 1.99)§ |
| Non-elevated hs-cTnT (<14 ng/L) & low ABI (<0.9) | 574 | 140 | 5358.6 | 2.61 | 2.79(2.34, 3.33)§ | 1.87 (1.52, 2.31)§ |
| Elevated hs-cTnT (≥14 ng/L) & low ABI (<0.9) | 238 | 55 | 1325.6 | 4.15 | 4.82 (3.67, 6.34)§ | 2.04 (1.45, 2.88)§ |
| Trend p-value | <0.001 | <0.001 | ||||
| Joint expected HR (multiplicative model) | 8.30 | 3.09 | ||||
| Joint expected HR (additive model) | 4.77 | 2.52 | ||||
| LR test p-value for multiplicative interaction | 0.002 | 0.042 | ||||
| RERI (95% CI) test for additive interaction | 0.06 (−1.36, 1.48) | −0.49 (−1.28, 0.31) | ||||
| Outcome ASCVD | ||||||
| Non-elevated hs-cTnT (<14 ng/L) & normal ABI (0.9 – 1.4) | 9206 | 1958 | 113,501.9 | 1.73 | 1 (reference) | 1 (reference) |
| Elevated hs-cTnT (≥14 ng/L) & normal ABI (0.9 – 1.4) | 876 | 322 | 7008.5 | 4.60 | 2.83 (2.52, 3.19)§ | 1.67 (1.44, 1.93)§ |
| Non-elevated hs-cTnT (<14 ng/L) & low ABI (<0.9) | 577 | 220 | 4965.9 | 4.43 | 2.67 (2.32, 3.07)§ | 1.67 (1.42, 1.97)§ |
| Elevated hs-cTnT (≥14 ng/L) & low ABI (<0.9) | 238 | 90 | 1229.8 | 7.32 | 4.88 (3.94, 6.04)§ | 2.05 (1.58, 2.66)§ |
| Trend p-value | <0.001 | <0.001 | ||||
| Joint expected HR (multiplicative model) | 7.56 | 2.79 | ||||
| Joint expected HR (additive model) | 4.50 | 2.34 | ||||
| LR test p-value for multiplicative interaction | 0.001 | 0.08 | ||||
| RERI (95% CI) test for additive interaction | 0.38 (−0.74, 1.49) | −0.29 (−0.89, 0.31) | ||||
p-value: †<0.05, ‡<0.01, §<0.001.
Abbreviations: ABI, ankle-brachial index; ASCVD, Atherosclerotic cardiovascular disease; hs-cTnT, highly-sensitive cardiac troponin-T; CHD, coronary heart disease; CI, confidence interval; HR, hazard ratio; LR, likelihood ratio; RERI, relative excess risk due to interaction.
Models were adjusted for age (years), sex (male, female), race/ethnicity (White, Black, Hispanic, Asian, other), education (<high school, high school complete, some college, college complete, graduate), pack years of smoking (continuous), alcohol drinks/week (continuous), exercise (met-hr/wk continuous), body mass index (continuous), hypertension (yes/no), diabetes (yes/no), glomerular filtration rate (continuous), total cholesterol (continuous), HDL cholesterol (continuous), triglyceride (continuous), hypertension medication (yes/no), statin (yes/no), family history of CVD (yes/no) and cohort indicator (MESA/CHS).
Expected HR for additive model was calculated as HR10 + HR01–1, where HR10 is the hazard ratio for elevated hs-cTnT but normal ABI, and HR01 is the hazard ratio for non-elevated hs-cTnT but low ABI. Expected HR for multiplicative model was calculated as HR10*HR01.