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Table 2 Ottawa SAH prediction algorithm pathways and anticipated predictive probability of each pathway based on our experience at The Ottawa Hospital

From: The Ottawa SAH search algorithms: protocol for a multi- centre validation study of primary subarachnoid hemorrhage prediction models using health administrative data (the SAHepi prediction study protocol)

Prediction Model A – Recursive Partitioning Model
Prediction Model Pathways Diagnostic codes (ICD10CA) Procedural codes (CCI) Admission characteristics Predicted probability of pSAH (%)
SAH (ICD 160) ICH (ICD 161) Other nontraumatic ICH (ICD 162) Other CVD (ICD 167) Intracranial Injury (ICD S06) Therapeutic Carotid Artery Occlusion (CCI 1JE51) Therapeutic Occlusion Intracranial Vessels (CCI 1JW51) Extracranial Vessel Imaging (CCI 3JW10) LOS (days) Admission Type
1 +           97.6
2 +       +     100
3 +        ≥2   83.7
4 +        < 2   100
5       +     76.9
6 +         41.2
7 +        Urgent 28.6
8 +        Nonurgent 100
9     +     100
10   +      26.7
11   +   +    100
12   +     15.4
13 +       28.6
14 +      10.3
15 +     Urgent 2.9
16 +     Nonurgent 75
17      0.1
Prediction Model B – SAH prediction point system
Prediction Variables Diagnostic codes (ICD10CA) Procedural codes (CCI) Admission characteristics
SAH (ICD 160) ICH (ICD 161) Other CVD (ICD 167) Intracranial Injury (ICD S06) Other postprocedural nervous system disorder (ICD G97) Therapeutic Occlusion Intracranial Vessels (CCI 1JW51) Extracranial Vessel Imaging (CCI 3JW10) CT scan (soft tissue of neck) (3FY20) CT scan (abdominal cavity) (3OT20) LOS Admission Type (Urgent or Emergent) Admitted to ICU
≤ 2 days ≥ 3 days
Points 6 4 4 3 4 3 1 −3 −2 0 −1 2 1
Score Predicted probability of pSAH (%)
≤ 0 0
1 0.1
2 0.1
3 1.4
4 2.4
5 17.2
6 33.3
7 63.9
8 94.6
9 97.0
10 100
11 100
12 98.8
≥ 13 100
Prediction Model C – Prevalence-adjusted SAH Prediction Point System
Prediction Variables Diagnostic codes (ICD10CA) Procedural codes (CCI)
SAH (ICD 160) ICH (ICD 161) Therapeutic Occlusion Intracranial Vessels (CCI 1JW51)
Points 2 1 1
Score 50%tile Predicted probability of pSAH (%) (2.5–97.5%ile)
0 0 (0–0.01)
1 2.5 (0–5.6)
2 20 (5–35.3)
3 100 (100–100)
4 100 (100–100)
  1. Cells containing “+” indicate that the relevant code was present and of interest to the pathway, “-” indicates that the code was of interest to the pathway, but was absent. Blank cells indicate that the corresponding code was not considered for that pathway. ICD10CA International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Canada, ICD International Classification of Diseases and Related Health Problems, CCI Canadian Classification of Health Interventions, SAH subarachnoid hemorrhage, ICH intracranial hemorrhage, CVD cerebrovascular disease, LOS length of stay, pSAH primary subarachnoid hemorrhage