feature: NEWS2 Composite Scoring Engine
This commit is contained in:
voltsrage
@@ -0,0 +1,105 @@
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using StackExchange.Redis;
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public static class News2Calculator
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{
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// The 7 NEWS2 parameter codes. Order is stable for MGET.
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public static readonly IReadOnlyList<string> ParameterCodes = new[]
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{
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"RESP_RATE", "SPO2", "SYSTOLIC_BP", "HEART_RATE", "AVPU", "TEMP_C", "SUPPLEMENTAL_O2"
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};
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public static RedisKey[] AllParameterKeys(Guid encounterId) =>
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ParameterCodes
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.Select(code => (RedisKey)$"news2:{encounterId}:{code}")
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.ToArray();
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public static string ParameterKey(Guid encounterId, string code) =>
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$"news2:{encounterId}:{code}";
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public static bool IsNews2Code(string observationCode) =>
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ParameterCodes.Contains(observationCode);
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// --- Individual parameter scoring ---
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// Each method returns 0-3 per the official NEWS2 scoring table.
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public static int ScoreRespRate(decimal value) => value switch
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{
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<= 8 => 3,
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<= 11 => 1,
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<= 20 => 0,
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<= 24 => 2,
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_ => 3 // >= 25
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};
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// Scale 1 (standard). Scale 2 (hypercapnic respiratory failure) is not implemented.
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public static int ScoreSpo2(decimal value) => value switch
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{
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<= 91 => 3,
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<= 93 => 2,
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<= 95 => 1,
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_ => 0 // >= 96
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};
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public static int ScoreSystolicBp(decimal value) => value switch
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{
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<= 90 => 3,
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<= 100 => 2,
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<= 110 => 1,
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<= 219 => 0,
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_ => 3 // >= 220
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};
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public static int ScoreHeartRate(decimal value) => value switch
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{
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<= 40 => 3,
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<= 50 => 1,
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<= 90 => 0,
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<= 110 => 1,
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<= 130 => 2,
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_ => 3 // >= 131
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};
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// AVPU: Alert=0, Voice/Pain/Unresponsive=3 (any non-Alert scores 3)
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public static int ScoreConsciousness(decimal value) => value switch
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{
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0 => 0, // Alert
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_ => 3 // Voice (1), Pain (2), Unresponsive (3)
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};
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public static int ScoreTemperature(decimal value) => value switch
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{
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<= 35.0m => 3,
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<= 36.0m => 1,
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<= 38.0m => 0,
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<= 39.0m => 1,
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_ => 2 // >= 39.1
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};
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// 0 = room air, 1 = on supplemental oxygen
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public static int ScoreSupplementalO2(decimal value) =>
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value >= 1 ? 2 : 0;
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// Dispatch to the correct scoring function by observation code.
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public static int ScoreParameter(string observationCode, decimal value) =>
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observationCode switch
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{
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"RESP_RATE" => ScoreRespRate(value),
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"SPO2" => ScoreSpo2(value),
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"SYSTOLIC_BP" => ScoreSystolicBp(value),
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"HEART_RATE" => ScoreHeartRate(value),
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"AVPU" => ScoreConsciousness(value),
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"TEMP_C" => ScoreTemperature(value),
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"SUPPLEMENTAL_O2" => ScoreSupplementalO2(value),
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_ => throw new ArgumentOutOfRangeException(nameof(observationCode))
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};
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// Determine risk level from total score and single-param-3 flag.
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public static string DetermineRiskLevel(int totalScore, bool hasSingleParamThree) =>
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totalScore switch
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{
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>= 7 => "HIGH",
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>= 5 => "MEDIUM",
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_ when hasSingleParamThree => "LOW_MEDIUM",
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_ => "LOW"
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};
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}
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@@ -0,0 +1,224 @@
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using System.Text.Json;
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using Microsoft.EntityFrameworkCore;
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using Prometheus;
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using StackExchange.Redis;
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public class News2Detector
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{
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private const int News2TtlSeconds = 14400; // 4 hours
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private static readonly JsonSerializerOptions CachedParamJsonOptions = new()
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{
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PropertyNameCaseInsensitive = true
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};
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private readonly IConnectionMultiplexer _redis;
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private readonly IServiceProvider _services;
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private readonly ClinicalMetrics _metrics;
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private readonly ILogger<News2Detector> _logger;
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public News2Detector(
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IConnectionMultiplexer redis,
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IServiceProvider services,
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ClinicalMetrics metrics,
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ILogger<News2Detector> logger)
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{
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_redis = redis;
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_services = services;
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_metrics = metrics;
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_logger = logger;
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}
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public async Task<News2Result> ProcessObservationAsync(
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Guid encounterId,
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Guid patientId,
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string observationCode,
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decimal value,
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CancellationToken ct = default)
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{
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if (!News2Calculator.IsNews2Code(observationCode))
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return News2Result.NotNews2Code;
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using var timer = _metrics.News2ScoringDuration.NewTimer();
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var cache = _redis.GetDatabase();
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// Compute the individual score and store in Redis
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var individualScore = News2Calculator.ScoreParameter(observationCode, value);
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var paramData = JsonSerializer.Serialize(new
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{
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value,
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score = individualScore,
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recordedAt = DateTimeOffset.UtcNow
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}, CachedParamJsonOptions);
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await cache.StringSetAsync(
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News2Calculator.ParameterKey(encounterId, observationCode),
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paramData,
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TimeSpan.FromSeconds(News2TtlSeconds));
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// Fetch all 7 parameter keys in one MGET round-trip
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var allKeys = News2Calculator.AllParameterKeys(encounterId);
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var allValues = await cache.StringGetAsync(allKeys);
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// Check completeness — all 7 must be present
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var scores = new int?[7];
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for (int i = 0; i < 7; i++)
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{
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if (!allValues[i].HasValue)
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{
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_logger.LogDebug(
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"NEWS2 incomplete for encounter {Id}: {Code} missing ({Present}/7 present)",
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encounterId, News2Calculator.ParameterCodes[i],
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allValues.Count(v => v.HasValue));
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return News2Result.IncompleteParameters(allValues.Count(v => v.HasValue));
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}
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var cached = JsonSerializer.Deserialize<News2CachedParam>(allValues[i]!, CachedParamJsonOptions);
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scores[i] = cached?.Score;
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}
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// All 7 present — compute aggregate
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var paramScores = scores.Select(s => s!.Value).ToArray();
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var totalScore = paramScores.Sum();
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var hasSingleParamThree = paramScores.Any(s => s == 3);
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var riskLevel = News2Calculator.DetermineRiskLevel(totalScore, hasSingleParamThree);
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// Persist the score to PostgreSQL
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var scoreId = await PersistScoreAsync(
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encounterId, patientId, totalScore, riskLevel,
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paramScores, hasSingleParamThree, ct);
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_logger.LogInformation(
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"NEWS2 score {Score} ({Risk}) for encounter {Id} — components: {Components}",
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totalScore, riskLevel, encounterId,
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string.Join(",", News2Calculator.ParameterCodes.Zip(paramScores, (c, s) => $"{c}={s}")));
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// Create alert if warranted
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var alertCreated = false;
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if (riskLevel == "HIGH")
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{
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alertCreated = await TryCreateAlertAsync(
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encounterId, patientId, AlertType.News2Emergency, AlertSeverity.Critical,
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totalScore, riskLevel, paramScores, ct);
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}
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else if (riskLevel == "MEDIUM" || riskLevel == "LOW_MEDIUM")
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{
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alertCreated = await TryCreateAlertAsync(
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encounterId, patientId, AlertType.News2Warning, AlertSeverity.Warning,
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totalScore, riskLevel, paramScores, ct);
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}
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return new News2Result(
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News2Outcome.ScoreComputed, totalScore, riskLevel, alertCreated, 7, hasSingleParamThree);
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}
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private async Task<Guid> PersistScoreAsync(
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Guid encounterId, Guid patientId,
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int totalScore, string riskLevel,
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int[] paramScores, bool hasSingleParamThree,
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CancellationToken ct)
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{
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using var scope = _services.CreateScope();
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var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
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var score = new News2Score
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{
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Id = Guid.NewGuid(),
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EncounterId = encounterId,
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PatientId = patientId,
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TotalScore = totalScore,
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RiskLevel = riskLevel,
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RespRateScore = paramScores[0],
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Spo2Score = paramScores[1],
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SystolicBpScore = paramScores[2],
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HeartRateScore = paramScores[3],
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ConsciousnessScore = paramScores[4],
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TemperatureScore = paramScores[5],
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SupplementalO2Score = paramScores[6],
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HasSingleParamThree = hasSingleParamThree,
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CalculatedAt = DateTimeOffset.UtcNow
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};
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db.News2Scores.Add(score);
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await db.SaveChangesAsync(ct);
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_metrics.News2ScoresTotal.WithLabels(riskLevel).Inc();
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return score.Id;
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}
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private async Task<bool> TryCreateAlertAsync(
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Guid encounterId, Guid patientId,
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AlertType alertType, AlertSeverity severity,
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int totalScore, string riskLevel, int[] paramScores,
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CancellationToken ct)
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{
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using var scope = _services.CreateScope();
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var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
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await using var tx = await db.Database.BeginTransactionAsync(ct);
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var alertId = Guid.NewGuid();
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var triggeredAt = DateTimeOffset.UtcNow;
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var details = BuildDetails(totalScore, riskLevel, paramScores);
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var affected = await db.Database.ExecuteSqlInterpolatedAsync($"""
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INSERT INTO clinical_alerts
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(id, encounter_id, patient_id, alert_type, severity, details, status, triggered_at)
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SELECT {alertId}, {encounterId}, {patientId},
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{alertType.ToDbString()}, {severity.ToDbString()}, {details}, 'OPEN', {triggeredAt}
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WHERE NOT EXISTS (
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SELECT 1 FROM clinical_alerts
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WHERE encounter_id = {encounterId}
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AND alert_type = {alertType.ToDbString()}
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AND status IN ('OPEN', 'ESCALATED')
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)
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""", ct);
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if (affected == 0)
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{
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await tx.RollbackAsync(ct);
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return false;
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}
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db.OutboxEvents.Add(new OutboxEvent
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{
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Id = Guid.NewGuid(),
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Topic = "alert.generated",
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Payload = JsonSerializer.Serialize(new
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{
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alertId,
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encounterId,
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patientId,
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alertType = alertType.ToDbString(),
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severity = severity.ToDbString(),
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triggeredAt,
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news2Score = totalScore,
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news2RiskLevel = riskLevel,
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partitionKey = encounterId.ToString()
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}),
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PartitionKey = encounterId.ToString(),
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CreatedAt = DateTimeOffset.UtcNow
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});
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await db.SaveChangesAsync(ct);
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await tx.CommitAsync(ct);
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_metrics.ClinicalAlertsTotal
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.WithLabels(alertType.ToDbString(), severity.ToDbString()).Inc();
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_logger.LogWarning(
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"NEWS2 alert {AlertType} created for encounter {EncounterId} — score={Score} risk={Risk}",
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alertType.ToDbString(), encounterId, totalScore, riskLevel);
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return true;
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}
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private static string BuildDetails(int totalScore, string riskLevel, int[] paramScores)
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{
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var components = News2Calculator.ParameterCodes
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.Zip(paramScores, (code, score) => $"{code}={score}")
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.ToArray();
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return $"NEWS2 score {totalScore} ({riskLevel}): {string.Join(", ", components)}.";
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}
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}
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