feature: NEWS2 Composite Scoring Engine

2026-06-18 17:39:31 +08:00
parent c3fbc20ddc
commit e6f7989298
31 changed files with 3118 additions and 45 deletions
@@ -0,0 +1,105 @@
+using StackExchange.Redis;
+
+public static class News2Calculator
+{
+    // The 7 NEWS2 parameter codes. Order is stable for MGET.
+    public static readonly IReadOnlyList<string> ParameterCodes = new[]
+    {
+        "RESP_RATE", "SPO2", "SYSTOLIC_BP", "HEART_RATE", "AVPU", "TEMP_C", "SUPPLEMENTAL_O2"
+    };
+
+    public static RedisKey[] AllParameterKeys(Guid encounterId) =>
+    ParameterCodes
+        .Select(code => (RedisKey)$"news2:{encounterId}:{code}")
+        .ToArray();
+
+    public static string ParameterKey(Guid encounterId, string code) =>
+        $"news2:{encounterId}:{code}";
+
+    public static bool IsNews2Code(string observationCode) =>
+        ParameterCodes.Contains(observationCode);
+
+    // --- Individual parameter scoring ---
+    // Each method returns 0-3 per the official NEWS2 scoring table.
+
+    public static int ScoreRespRate(decimal value) => value switch
+    {
+        <= 8  => 3,
+        <= 11 => 1,
+        <= 20 => 0,
+        <= 24 => 2,
+        _     => 3  // >= 25
+    };
+
+    // Scale 1 (standard). Scale 2 (hypercapnic respiratory failure) is not implemented.
+    public static int ScoreSpo2(decimal value) => value switch
+    {
+        <= 91 => 3,
+        <= 93 => 2,
+        <= 95 => 1,
+        _     => 0  // >= 96
+    };
+
+    public static int ScoreSystolicBp(decimal value) => value switch
+    {
+        <= 90  => 3,
+        <= 100 => 2,
+        <= 110 => 1,
+        <= 219 => 0,
+        _      => 3  // >= 220
+    };
+
+    public static int ScoreHeartRate(decimal value) => value switch
+    {
+        <= 40  => 3,
+        <= 50  => 1,
+        <= 90  => 0,
+        <= 110 => 1,
+        <= 130 => 2,
+        _      => 3  // >= 131
+    };
+
+    // AVPU: Alert=0, Voice/Pain/Unresponsive=3 (any non-Alert scores 3)
+    public static int ScoreConsciousness(decimal value) => value switch
+    {
+        0 => 0,  // Alert
+        _ => 3   // Voice (1), Pain (2), Unresponsive (3)
+    };
+
+    public static int ScoreTemperature(decimal value) => value switch
+    {
+        <= 35.0m => 3,
+        <= 36.0m => 1,
+        <= 38.0m => 0,
+        <= 39.0m => 1,
+        _        => 2  // >= 39.1
+    };
+
+    // 0 = room air, 1 = on supplemental oxygen
+    public static int ScoreSupplementalO2(decimal value) =>
+        value >= 1 ? 2 : 0;
+
+    // Dispatch to the correct scoring function by observation code.
+    public static int ScoreParameter(string observationCode, decimal value) =>
+        observationCode switch
+        {
+            "RESP_RATE"       => ScoreRespRate(value),
+            "SPO2"            => ScoreSpo2(value),
+            "SYSTOLIC_BP"     => ScoreSystolicBp(value),
+            "HEART_RATE"      => ScoreHeartRate(value),
+            "AVPU"            => ScoreConsciousness(value),
+            "TEMP_C"          => ScoreTemperature(value),
+            "SUPPLEMENTAL_O2" => ScoreSupplementalO2(value),
+            _                 => throw new ArgumentOutOfRangeException(nameof(observationCode))
+        };
+
+    // Determine risk level from total score and single-param-3 flag.
+    public static string DetermineRiskLevel(int totalScore, bool hasSingleParamThree) =>
+        totalScore switch
+        {
+            >= 7                              => "HIGH",
+            >= 5                              => "MEDIUM",
+            _ when hasSingleParamThree        => "LOW_MEDIUM",
+            _                                 => "LOW"
+        };
+}