Comparative performance of six general comorbidity indices for predicting survival in patients with aorto-iliac...

General comorbidity indices may identify patients with a limited life expectancy and help in the indication of prophylactic interventions, such as the repair of intact abdominal aortic and iliac aneurysms (AAAI). The aim of this study was to compare the predictive performance of six general comorbidity indices in patients with AAAI and indication for elective repair.

Retrospective cohort study of consecutive patients with AAAI and indication for repair according to size. The main outcome was 5-year survival. The predictive performance of the Charlson Comorbidity Index (CCI), the number of active (COM-A) and total (COM-T) comorbidities, the number of chronically prescribed medications (POLIF), and the Comorbidity Polypharmacy Score obtained by adding POLIF+COM-A (CPS-A) or POLIF+COM-T (CPS-T) was evaluated with adjusted penalized splines and Cox regression models. Areas under the curve and C-statistics were compared with chi-square tests.

A total of 424 patients were evaluated (median age 76 years old; 92.2% male) of whom 110 (25.9%) underwent surveillance and 314 (74.1%) elective repair (19.7% open and 80.3% endovascular). Median baseline score [25-75 interquartile range] of comorbidity indices were: CCI 2.00 [1-3], POLIF 6.00 [4-9], COM-A 6.00 [4-7.75], COM-T 7.00 [5-9], CPS-A 12.00 [9-16] and CPS-T 13.00 [10-17]. During follow-up 292 patients (68.9%) died with 2- and 5- year survival rates of 75.9% and 54.5%, respectively. All indices were significantly associated with 5-year survival (CCI Hazard Ratio (HR)=1.2, p<0.001, COM-A HR=1.11 p<0.001, COM-T HR=1.09 p<0.001, POLIF HR=1.07 p<0.001, CPS-A HR=1.05 p<0.001, CPS-T HR=1.05 p<0.001), without significant differences in their predictive performance. Patients with COM-A>5 and POLIF>6 (best cut-offs on a ROC curve) had 2-/5-year survival rates of 68.7%/44.3% and 66.5%/39.0%, respectively, these figures being 17-18% at 2 years and 24-29% at 5 years lower than those observed with COM-A≤5 or POLIF≤6.

All evaluated general comorbidity indices demonstrated good and similar performance for assessing survival in patients with AAAI and indication for elective repair. Any of them can be useful in decision-making.