- Comparison of baseline characteristics
Compared with free medical care, patients with other health insurance status have a significantly lower age (P ˂ 0.05 ~ 0.001), the youngest of which is new rural cooperative medical system. The gender proportion was similar in all groups except for municipal urban resident medical insurance and self-payment. Although there were significantly differences in Cr and CysC, which of new rural cooperative medical system was low, there was no statistically significant difference in ANCOVA analysis after controlling for age. ANCOVA analyses of CK-MB and cTnI controlling for age showed no statistically significant difference. These results suggest that there is no difference in baseline disease status among hospitalized patients despite differences in age.(Table 1).
2.Comparison of hospitalization costs of patients with different health insurance status
The difference in hospital expenses of different health insurance status was statistically significant, among which free medical care was the largest. ANCOVA analyses controlling for age showed that the difference was still statistically significant, suggesting that age was not the main factor determining the cost, and there were differences in hospital expenses of different health insurance status. Comorbidity is very likely to have more drugs causing cost differences, and with the increase of age, drug cost differences may be large. The new rural cooperative medical system has the lowest age, then drug cost is small. However, statistical differences still existed among different health insurance status after controlling for age. (Table 2)
Nursing cost is theoretically related to the increase of age. The older the patient is, the more dependent on nursing fee is. However, there is no statistical significance in the influence of age on nursing fee among AMI patients, and the difference of nursing fee between health insurance status has statistical significance, and the nursing fee of new rural cooperative medical system is low. (Table 2)
The difference in length of stay among different health insurance status was statistically significant, among which the maximum length of stay was at free medical care and the shortest was at the new rural cooperative medical system. ANCOVA analysis controlling the age showed that the difference was still statistically significant, suggesting that age was not the main factor determining the length of stay, and there were differences in length of stay among different health insurance status. The difference of daily hospitalization cost between health insurance status was statistically significant, and the daily hospitalization cost of the new rural cooperative medical system was the highest. After controlling for age, ANCOVA analysis showed that the difference was still statistically significant, suggesting that age was not the main factor determining the cost. (Table 2)
The daily drug cost is theoretically related to the increase of age and comorbidity. However, there is no statistical significance in the influence of age on daily drug cost among AMI patients, and the difference of daily drug cost between health insurance status is statistically significant, and the daily drug cost at free medical care is highest. The daily nursing cost was the highest at free medical care, but ANCOVA analysis after controlling for age showed no statistically significant differences in age and daily nursing cost, suggesting no impact of age. The percent of nursing cost was statistically significant among different health insurance status, and the percent in new rural cooperative medical system was the smallest. However, ANCOVA analysis after controlling for age showed no statistical significance in the percent of nursing cost, suggesting which was age-related. (Table 2)
- Analyses of relevant factors
Further studies were conducted on the factors influencing the total cost of hospitalization, and blood potassium (β =0.367, P=0.0001), stents (β =0.362, P=4×10-27), CK-MB (β =0.076, P=0.002), and hemoglobin (β =0.200, P=0.032) were the main influencing factors, independent of age. Factors affecting length of stay included age (β =0.487, P=0.000001), serum sodium (β =1.031, P=5×10-11), health insurance status (β =-0.305, P=0.0000001), systolic blood pressure (β =-0.334, P=0.004), and cTnI (β =0.046, P=0.022). Factors affecting nursing costs include age (β =0.328, P=0.045), health insurance status (β =-0.319, P=0.004), and HDL (β =0.390, P=0.022). Factors influencing daily hospitalization costs included potassium (β =0.513, P=0.0003), stent (β =0.394, P=4×10-23), health insurance status (β =0.296, P=0.0001), and age (β =-0.298, P=0.009). Factors for daily nursing costs included HDL (β =0.353, P=0.007) and age (β =0.321, P=0.015). Factors affecting the percent of nursing cost included HDL (β =0.360, P=0.004), age (β =0.538, P=0.00001) and stent (β =-0.332, P=5×10-13). (Table 3)
Factors influencing the occurrence of clinical events included health insurance status (β =-0.186, OR=0.830, 95%CI 0.694-0.993, P=0.041), age (β =0.045, OR=1.046, 95%CI 1.024-1.069, P=4×10-5), serum sodium (β =0.04, OR=0.961, 95%CI 0.945-0.977, P=2×10-6), heart rate (β =0.034, OR=1.035, 95%CI 1.019-1.052, P=3×10-5). Treatment factors influencing the occurrence of clinical events included health insurance status (β =-0.346, OR=0.708, 95%CI 0.626-0.799, P=3×10-8), statins (β =-1.118, OR=0.327, 95%CI 0.191-0.560, P=5×10-5), and percent of nursing cost (β =0.466, OR=1.594, 95%CI 1.068-2.379, P=0.022), and daily medication cost (β =0.001, OR=1.001, 95%CI 1.000-1.001, P=0.007). (Table 3)