Finally, 304 patients with sufficient available clinical and biological information were selected for this study. The average age was 77 ± 8 years, and 233 (76.6%) patients were males. There were 120 (39.5%) patients with age ≥ 80 years and 8 (2.6%) patients with age ≥ 90 years.
Testing of platelet aggregation
During aspirin therapy, the range of LTA-AA was from 0.84% to 34.91%, with a median value of 9.69% (IQR 6.80%-12.38%). There were 3 (0.99%) patients with LTA-AA >20%. According to the aforementioned definition, there were 76 patients in the HTPR group (LTA-AA ≥ 12.38%), with a median value of 14.41% (IQR 12.94%-16.82%), and there were 228 patients in the non-HTPR group (LTA-AA < 12.38%), with a median value of 8.69% (IQR 5.83%-10.48%).
Clinical features of elderly patients with ASCVD classified by HTPR
The clinical and biological characteristics of the study participants divided according to HTPR are shown in Table 1 and Table 2. Patients in the HTPR group were older than patients in the non-HTPR group (mean age: 79 ± 7 vs. 76 ± 8 years, p = 0.008). In terms of the ASCVD spectrum, patients in the HTPR group had an increased presence of ischemic stroke or transient ischemic attacks, and fewer patients had a history of coronary heart disease than those in the non-HTPR group (p < 0.01). The ratio of angiotensin converting enzyme inhibitors/angiotensin receptor blockers (ACEIs/ARBs) medications was higher in the HTPR group (p = 0.046). There were no significant diﬀerences in daily aspirin dose between the two groups (p > 0.05). Patients in the HTPR group had lower levels of eGFR (average values: 65.2 vs. 71.8 mL/min/1.73 m2, p = 0.002), indicating poorer renal function than patients in the non-HTPR group. The hemoglobin level was significantly lower in the HTPR group than that in the non-HTPR group (p < 0.001).
Linear correlation analysis showed that LTA-AA was significantly correlated with age (r = 0.128, p = 0.025), hemoglobin (r = - 0.216, p < 0.001) and eGFR (r = - 0.230, p < 0.001) for the entire study population. Multivariate regression analysis of HTPR included the following independent variables in the model: age, systolic blood pressure, eGFR, hemoglobin, nitrate use, proton pump inhibitor (PPI) use and ACEI/ARB use. The results showed that eGFR was an independent factor associated with HTPR (OR: 0.984, 95% CI: 0.980-0.988, p < 0.001).
Clinical features of elderly patients with ASCVD classified by renal function
Study participants were stratified by eGFR. Clinical and biologic characteristics with statistical significance are shown in Table 3. In all enrolled patients, 16.1% had a normal eGFR, 52.6% had a slight decrease in eGFR, and 31.3% had a moderate decrease in eGFR. LTA-AA was higher in patients with decreased eGFR than in those with normal eGFR. Patients with moderately decreased eGFR had a higher frequency of HTPR than patients with slightly decreased eGFR or normal eGFR (35.8%, 22.5%, 12.2%, respectively, p < 0.05). Renal function deteriorates with age. As eGFR decreased, a descending trend of diastolic blood pressure levels and hemoglobin levels, as well as an ascending trend of serum creatinine, urea and uric acid levels appeared. Patients with moderately decreased eGFR had higher MPV (mean platelet volume)/PLT (platelet count) ratios and neutrophil percentages compared to those with slightly decreased eGFR (p < 0.05). Compared with patients with normal eGFR, patients with moderately decreased eGFR had an increased presence of ischemic stroke/transient ischemic attack, peripheral artery stenosis and hyperlipidemia (p < 0.05), and the ratios of ACEIs/ARBs, statins and PPI medications were higher (p < 0.05). The results of ROC analysis showed that eGFR levels in all patients were calculated with 70.3mL/min/1.73m2 as a cutoff value to predict HTPR, with an area under the ROC curve of 0.620 (95% CI 0.551-0.689, p = 0.002).