Table 2
Comparison of characteristics between the two groups in 2014 after PSM
| Variables | Pilot group (n=4907) | Control group (n=9814) | P value | Standardised differences* |
| Sex, n (%) | <0.767 | |||
| Male | 2650 (54.00) | 5322 (54.23) | 0.005 | |
| Female | 2257 (46.00) | 4492 (45.77) | 0.005 | |
| Age (years), mean±SD | 62.44±10.69 | 62.44±10.57 | 0.983 | 0.000 |
| Number of comorbidities, n (%) | 0.966 | |||
| 0 | 1800 (36.68) | 3605 (36.73) | 0.001 | |
| 1 | 1020 (20.79) | 2043 (20.82) | 0.001 | |
| ≥2 | 2087 (42.53) | 4166 (42.45) | 0.002 | |
| Number of complications, n (%) | 0.964 | |||
| 0 | 1343 (27.37) | 2689 (27.40) | 0.001 | |
| 1 | 1473 (30.02) | 2964 (30.20) | 0.004 | |
| ≥2 | 2091 (42.61) | 4161 (42.40) | 0.004 | |
| Types of medical insurance, n (%) | 0.756 | |||
| Urban employees | 4725 (96.29) | 9460 (96.39) | 0.005 | |
| Urban residents | 182 (3.71) | 354 (3.61) | 0.005 | |
| Grade of hospitals, n (%) | 0.990 | |||
| Primary hospitals | 1252 (25.51) | 2498 (25.45) | 0.001 | |
| Secondary hospitals | 2678 (54.58) | 5368 (54.70) | 0.006 | |
| Tertiary hospitals | 977 (19.91) | 1948 (19.85) | 0.002 |
*For continuous variables, the standardised differences is defined as
where
and
indicate the sample mean of the covariates in pilot and control groups, respectively, while
and
denote the sample variance. For categorical variables, the standardised differences is defined as-
where Ppilot and Pcontrol denote the prevalence of variables in the two groups.
PSM , propensity score matching .
