Income-Based Inequalities in Five-Year Survival after Coronary Artery Bypass Grafting and Percutaneous Coronary Intervention among Formally Employed Adults in Colombia: A Nationwide Cohort Study.

BACKGROUND

Myocardial revascularization by coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) lowers mortality, yet long-term outcomes may vary by socioeconomic status despite broadly similar access to care.

OBJECTIVE

To examine the association between income-measured in legal monthly minimum wages (MMW)-and five-year survival after revascularization in formally employed Colombians (2012-2018).

METHODS

This was a retrospective cohort study using linked national administrative datasets. Income was grouped into quartiles at cohort entry. The primary outcome was five-year mortality. Analyses were stratified by procedure (CABG, PCI). Multivariable Cox models were used to estimate adjusted hazard ratios (aHRs), controlling for age, sex, region, Charlson Comorbidity Index, recent acute myocardial infarction, valve surgery within 30 days, and pre-procedural cardiac rehabilitation (30 days). Socioeconomic gradients were summarized using the Relative Index of Inequality (RII) and the Slope Index of Inequality (SII; absolute difference per 100,000 patients).

RESULTS

Among 8,128 patients (mean age = 55.0 ± 9.3 years; 11.3% women), 2,131 underwent CABG and 5,997 underwent PCI. After CABG, five-year mortality was 13.2% in Q1 vs 7.8% in Q4 (p < 0.01); aHRs (vs Q1) were 0.60 (95% CI = 0.40-0.90) for Q2, 0.56 (0.38-0.84) for Q3, and 0.58 (0.38-0.88) for Q4 (all p ≤ 0.01). After PCI, mortality declined from 11.7% (Q1) to 6.5% (Q4) (p < 0.01); only Q4 remained significant after adjustment (aHR = 0.64; 95% CI = 0.49-0.82; p < 0.01). Inequality indices confirmed the gradient: for CABG, SII = 4.14 per 100,000 (95% CI = 3.30-4.98; p < 0.01) and RII = 1.97 (1.17-3.31; p = 0.01); for PCI, SII = 3.13 per 100,000 (2.74-3.52; p < 0.01) and RII = 1.81 (1.32-2.48; p < 0.01).

CONCLUSIONS

Lower income is associated with worse five-year survival after myocardial revascularization, with larger absolute and relative inequalities after CABG than after PCI.