Westchester County Community Health Electronic Syndromic Surveillance (CHESS)

Transcription

1 Andrew J. Spano, Westchester County Executive Westchester County Community Health Electronic Syndromic Surveillance (CHESS) October 17, 2006 DEPARTMENT OF HEALTH Joshua Lipsman, M.D., M.P.H., Commissioner

2 Westchester County COMMUNITY HEALTH ELECTRONIC SYNDROMIC SURVEILLANCE (CHESS) Background and Goals System Operation Project Development Analytic Methods Future Directions

3 BACKGROUND Project began in early 2001 under a grant from NYSDOH Events of and following September 11 th, 2001 accelerated project development Additional funding for the project was received from CDC through Congresswoman Lowey s office and NYSDOH.

4 GOALS Establish a real-time electronic public health surveillance system To detect disease outbreaks To provide potential early warning of a bioterrorism event or disease outbreak To report back to health care providers any possible unusual occurrences of illness or symptoms

5 DATA COLLECTION Electronically collect EXISTING data from information systems at Hospitals (emergency & outpatient departments) Health Centers Physician Offices & Freestanding Clinics Emergency Services Pharmacies Data automatically extracted and transmitted to WCDOH (via IT server) daily for the previous 24 hours activities

6 VARIABLES COLLECTED Facility Name or Identifier Date of Encounter Time of Encounter Patient Age or Date of Birth Patient Gender Patient Zip Code Patient Municipality Patient Unique Identifier (Medical Record Number) Chief Complaint Admitting and Final Diagnosis as Available Patient Type (admission vs. discharge) Clinic Type (emergency vs. outpatient)

7 CHESS: SYSTEM OPERATION Data Collection Data Analysis Notify Health-Care Providers Signal for Unusual or Increased Symptoms for a Syndrome YES Investigate NO Action

8 CHESS: CURRENT OPERATION STATUS Data from all (11) hospitals, representing roughly 900 ER visits daily 12 variables are collected from each hospital Data analysis is performed daily Chief complaints from patients are filtered into syndromic categories Monitoring four primary syndromes: Fever/Flu (13+), Respiratory syndromes (13+), GI/Diarrhea, Vomiting SPSS statistical package is used to run the analysis and detect peaks of visits for each primary syndrome Daily analysis results & graphs are distributed to WCDOH key staff members When signals detected, line lists of information are provided to clinical staff for further investigation with hospitals

9 DEVELOPMENT What It Took Two years of development Meetings and follow-up with 20 potential project participants Consultation and discussions with other agencies: NYCDOH Bergen County, NJ DOH CDC NYSDOH Other States Medical expertise (WCDOH, MAC members and ED physicians) Dedicated statistical staff at WCDOH Consultant Services IT expertise

10 DEVELOPMENT General Challenges Brand new area of work HIPAA and confidentiality concerns Encryption and file transfers Different computer systems and changes in vendors Not all variables collected electronically No standard file layout required Automation and coverage issues

11 Traditional Disease Surveillance Clinician reporting Private practices Clinics Hospitals Laboratory reporting

12 Goal of Syndromic Surveillance To detect outbreaks (clusters) of illness during the 2-7 day prodromal period, before characteristic symptoms allow definitive diagnosis.

13 Syndromic Categories Primary categories Fever/Flu Respiratory Vomiting GI /Diarrhea Secondary categories Sepsis / Unresponsive Rash Asthma Hemorrhage Neurologic

14 Filter Development Derived from a syndromic surveillance model developed by NYC and CDC for BT detection Adapted to WCDOH software standard Further developed / enhanced by clinicians

15 Include: Syndromic Category: Example: Fever CHILL, ELEVATED TEMP, FEB, FEEL HOT, FEELING HOT, FEELS HOT, FEV, FUO, HI TEMP, HIGH TEMP,NIGHT SWEAT, PAIN ALL OVER, SHIVER, TEMP 10, TEMP10 BODY and (ACHE TOTAL PAIN) GEN and (MALAIS) VIRAL and (SYN INF ILL FLU) BODY SHAKES, CHILL, FLUSH, HOT, ILI, I.L.I, PYREXIA, RIGORS Exclude: ACHILLES, ATTEMPT, BURN, TEMPORAL, TEMPLE, PSYCHO, PYSCHO, FLASH, FLUSH, HAY, NEUTROPEN, PORT

16 Syndrome Rate Calculation Daily syndrome rate is calculated as: Total cases in one syndrome category Total visits FEVER * RESPIRATORY * VOMITING GI / DIARRHEA * Excludes children under 13 years.

17 Analysis: Detect Aberrations Cumulative Sum (CUSUM) algorithm is used to detect aberrations from an expected mean CUSUM statistic tests have been validated with several types of infectious disease data sources* * Hutwagner et al., 2002

18 Analysis: Cumulative Sum (C1) Since CHESS system works with a 24-hour lag, yesterday is the event date C1 compares the syndrome rate of the event date with the mean of the syndrome rate for the previous seven days If the syndrome rate of the event date is more than [mean + 3 standard deviations] of the baseline, C1 is positive C1 is sensitive to detect one-day spikes of syndrome rates

19 Analysis: Cumulative Sum (C1) Fever & Flu Syndromes, Ages 13+ (sample data) SD Syndromic Rate * Mean Baseline Event Date 2/2/03 2/3/03 2/4/03 2/5/03 2/6/03 2/7/03 2/8/03 2/9/03 2/10/03 Date 5/20/03 5/21/03 5/22/03 5/23/03 5/24/03 5/25/03 5/26/03 5/27/03 5/28/03 Syndromic rate = number of syndrome cases / number of total ER admissions

20 ANALYSIS: Cumulative Sum (C2) C2 compares the syndrome rate of the event date with a baseline mean of the syndrome rate for the previous seven days, offset by three days If the syndrome rate of the event date is more than [mean + 3 standard deviations] of the baseline, C2 is positive C2 is sensitive to detect one-day spikes of disease incidence, but will not be affected by ongoing disease spikes

21 ANALYSIS: Cumulative Sum (C2) Respiratory Syndromes, Ages 13+ (sample data) 2SD 1 SD 3SD Mean Baseline 1/24/03 1/25/03 1/26/03 1/27/03 1/28/03 1/29/03 1/30/03 1/31/03 2/1/03 2/2/03 2/3/03 2/4/03 2/5/03 2/6/03 2/7/03 Date Event Date Syndromic Rate Syndromic Rate

22 ANALYSIS: Cumulative Sum (C3) C3 is complex: Σ (Syndrome rate (baseline mean + 1SD) ) > 2 SD of the baseline Only if there is more than one day when the syndrome rate is greater than the baseline (mean + 1 SD) C3 is sensitive to detect prolonged peaks of disease incidence (across several days)

23 ANALYSIS: Cumulative Sum (C3) 2SD >mean +1SD >mean +1SD 1/27/03 1/28/03 1/29/03 1/30/03 1/31/03 2/1/03 2/2/03 2/3/03 2/4/03 2/5/03 2/6/03 2/7/03 2/8/03 1/25/03 1/26/03

24 RESULTS Through mid October, 221 positive signals (156 days) None of the signals reflect an occurrence of concern Successfully detected flu season Successfully used post black-out in 2003

25 OTHER COMPONENTS OF CHESS Outpatient Data - Includes one health center - ICD 9 codes - No signal follow-up Pharmacy - Over-the-counter data 64 stores - 13 categories (e.g. cold/cough, antifever) - Medicaid OTC & prescription data Regional Sharing - NYSDOH & NYCDOH

26 CHESS: FUTURE DIRECTIONS Ongoing evaluation of filter Expansion of outpatient sites Sharing analysis with partners Emergency mode capability