Basic Information of Patients
The detailed process of selection and exclusion of patients in modeling group and validation group was shown in Figure 1. In total, 147 patients were included in the derivation study, while 68 patients were included in the validation cohort.
In the derivation cohort, 55 (37%) patients were male and 92 (63%) were female. The age of cases ranged from 37 to 87, the mean age was 61.3 ± 11.5 years, and approximately 39% of patients were over 65 years old. The baseline characteristics of the 147 patients with poor grade aSAH are presented in Table 1. A total of 124 (84.3%) patients accepted surgical therapies including coiling (29.2%) and clipping (55.1%). The rest of 23 (15.7%) patients accepted conservative treatments. The distribution of mRS score of 147 poor-grade aSAH patients accepted different treatment was shown in Figure 2 (A). In Figure 2 (B, C, D, E), patients accepted coiling or clipping had a better prognosis than patients accepted conservation treatment, but there was no statistical significance of prognosis between patients accepted coiling and clipping. There were 114 (77.6%) poor-grade aSAH patients with modified fisher grade above 2 and 85 (57.8%) patients were recorded with WFNS grade V. And the distribution of mRS score of 147 poor-grade aSAH patients with different modified Fisher grade was shown in Figure 2 (F). Figure 2 (G, H, I, J) reflects the influence of different modified Fisher grade groups on the prognosis of patients. During the 6 months’ follow-up after discharge, 85 patients (58%) had poor outcomes.
Of the 68 patients in the validation cohort, 25 (36.7%) patients were over 65 years old. A total of 44 (64.7%) poor-grade aSAH patients with a modified fisher grade above 2 and 40 (58.8%) patients presented with WFNS grade V. Forty-nine (72%) patients accepted surgical therapies. During the 6 months’ follow-up after discharge, 38 patients (56%) had poor outcomes. Specific data of validation cohort is presented in Table 1.
Univariate Analysis of Poor Outcome
The association between clinical variables and poor outcomes identified by univariate analysis are shown in Table 1. The poorer prognosis is associated with elderly age (age ≥ 65) (P = 0.027), intraventricular hemorrhage (P = 0.005), WFNS grade V (P < 0.001), conservative treatment (P = 0.009), modified fisher grade > 2 (P = 0.001), emergence of cerebral herniation (P < 0.001), aneurysm rebleeding (P = 0.004), CVS (P = 0.041) and DCI (P = 0.030). Medical history of patients and data of aneurysm were not significantly interrelated with clinical outcome (Table 1).
Multivariate Regression Analysis of Poor Outcome
Ten variables (P < 0.1 in univariate analysis) were entered into multivariate logistic regression. Table 2 showed age ≥ 65 years (OR, 3.534; p = 0.006), modified Fisher grade > 2 (OR, 2,972; p = 0.034), cerebral herniation (OR, 7.337; p < 0.001), WFNS V (OR, 2.638; p = 0.029), SDH (OR, 3.202; p = 0.032), conservative treatment (OR, 5.078; p = 0.019) and DCI (OR, 3.170; p = 0.016) are independent risk factors for poor outcomes. The Hosmer-Lemeshow test reflects a satisfied degree of consistency between the predicted risk of the model and the actual risk (P = 0.589, Table 2).
Development of the Scoring System
By integration of 7 independent risk factors including modified Fisher grade above grade II, age ≥ 65 years, conservative treatment, WFNS grade V, DCI, SDH, and cerebral herniation, a scoring system referred to as Poor-grade Aneurysmal Subarachnoid Hemorrhage Prognostic Scoring System (PASHPSS below) was then constructed (Table 3). Based on the β coefficient in the multivariate analysis, a score of 2 was assigned to cerebral herniation and conservative treatment respectively; a score of 1 was assigned to each other risk factors respectively; otherwise, 0 point was assigned. According to the sum of the scores (range from 0 - 9), the new model divided poor-grade aSAH patients into three prognostically different categories (Table 4): the predict risk of poor prognosis is 11% in patients with a total point of 0 - 1 (low risk category), 51% in those with a total point of 2 - 3 (intermediate risk category) and 87% in those with a total point of four or above (high risk category).
Discrimination and Calibration of the Scoring System
In modeling cohort, the AUC of PASHPSS was 0.844 (95% CI: 0.778 - 0.909; Figure 3). And the Hosmer-Lemeshow test showed a good calibration (P = 0.589).
The PASHPSS also showed good discrimination and good calibration in the validation cohort, with an AUC of 0.831 (95% CI, 0.732 - 0.929, Figure 3) and Hosmer-Lemeshow test fit well (P = 0.984). And in validation cohort (Table 3), the observed risks in the three risk groups were also closed to the predicted risks: low risk (actual observed risk of poor prognosis, 19%), intermediate risk (actual observed risk of poor prognosis, 48%) and high risk (actual observed risk of poor prognosis, 81%).