Detection of Carbon Monoxide Poisoning in Chief Complaint Data

1. Detection of Carbon Monoxide Poisoning in Chief Complaint Data Jian-Hua Chen, MD, MSPH Kathryn J. Schmit, MPH Hwa-Gan Chang, PhD James R. Miller, MD, MPH New York State Department of Health, Division of Epidemiology

2. Objective To assess the ability to identify cases of carbon monoxide (CO) poisoning from chief complaints (CC) in hospital emergency department (ED) records submitted daily to the New York State (NYS) Department of Health (DOH) Electronic Syndromic Surveillance System

3. CO poisoning statistics Each year in the U.S., about 15,000 people are treated in EDs for unintentional, non-fire-related exposure to CO Almost 500 deaths per year 63.4% of exposures occur in homes, from gas furnaces and heaters remainder in public places, cars Most exposures in winter

4. Buffalo’s October 2006 storm During the night of Oct 12-13, more than 2 feet of snow fell Almost 400,000 homes and businesses (70% of city) lost power ~100,000 had no power for 5 days, some for up to 12 days Newspapers reported that EDs received many patients suffering from CO poisoning (first stories said 170) 3 deaths

5. ED syndromic surveillance in NYS Data from EDs transmitted to NYSDOH daily Currently, 134 of 144 hospitals in upstate NY (exc. NYC) report Data includes medical record number (MRN); also patient’s age, sex, ZIP Code of residence chief complaint text (patient’s stated reason for visit, usually recorded by triage nurse, who may add comments)

6. Six syndromes monitored Chief complaints are searched for terms that classify visit by syndrome; for example:

9. Data submission following storm 10 hospitals in Erie County and 2 in Niagara County were submitting ED data in October 2006 Storm occurred on Thurs/Friday, and many hospitals did not submit ED data until the following week Chief complaints were examined retrospectively and as data received to monitor extent of problem

10. Hospital discharge data State Planning and Research Cooperative System (SPARCS) collects electronic ED records with diagnostic and procedural codes for administrative purposes Records due within 30 days of each year quarter In April 2007 we obtained SPARCS records for the 12 hospitals in study

11. Methods: CO-related CCs (ED syndromic data) CO exposure/poisoning identified in ED syndromic data by searching for relevant text strings in chief complaints: ‘CO EXP’, ‘CARBON MONOXIDE’, ‘CO POI’, ‘POSS CO’, etc. possible misspellings included, e.g., ‘HIGH CO2’, ‘CARBON MANOXIDE’ ‘USED STOVE FOR HEAT’, ‘GAS HEAT’, etc.

12. Methods: CO-related ICD-9 diagnosis codes (SPARCS data) CO exposure/poisoning identified by searching primary and first 3 secondary diagnosis codes in SPARCS records for CO-related ICD-9 codes: 986 (Toxic effect of carbon monoxide) E868 (Accidental poisoning by other utility gas or other carbon monoxide) E8683 (Accidental poisoning by CO from incomplete combustion of other domestic fuels) E8688 (Accidental poisoning by CO from other sources) E9821 (Poisoning by other CO, undetermined whether accidentally or purposely inflicted)

13. Methods: Record matching ED syndromic records matched to SPARCS records by medical record number (MRN) Records with either CO-related chief complaints or CO-related ICD-9 codes were examined

14. Results: Records Matching, October 13-20, 2006

15. Results: CO-related CCs and ICD-9 diagnoses In the week following the storm (Oct 13-20), 302 ED patients had CCs of CO exposure and/or SPARCS ICD-9 diagnoses of CO poisoning/exposure

16. CC+ records followed same pattern as ICD-9+ records

17. Syndromic alerts Daily syndromic alerts are generated based on 7-day CuSum statistics (CDC EARS) No Neuro or GI alerts were generated for Erie County hospitals A Respiratory alert was generated on Oct 14, but only 2 of these patients were diagnosed with CO poisoning Most others suffered from a variety of upper respiratory complaints or asthma

18. Symptoms mentioned in CCs of CO-related records: Most CCs mentioned NO symptoms, just exposure to CO or use of gas heating appliances Of those that did include symptoms, the most commonly mentioned complaints were neurological, then GI

19. Syndromic counts Of 260 records with CO-related ICD-9 codes, only 59 had CCs that were classified in one or more of our routinely monitored syndromes Neurologic – 46 GI – 23 Respiratory – 8 Fever – 3 Asthma – 1

20. Symptoms mentioned in CCs of CO-related records:ICD-9+, CC+ ICD-9+, CC(N=209) (N=51) Headache – 16 Dizziness – 4 Nausea/vom – 8 Lt-headed – 3 Sleepy – 3 Weakness – 1 Diff. breathing -- 1 Headache – 18 Dizziness – 15 Nausea/vom – 15 Lt-headed – 4 Syncope – 5 Weakness – 4 Diff. breathing – 4 Confusion -- 2

21. Discussion:  Event-related surveillance No data, no surveillance Hospitals usually have generators, so loss of power is probably not the reason for submission delays IT staff may be needed to re-boot a system that crashed Submitting syndromic surveillance data may be a low priority during an emergency For these reasons, automatic systems (both for data creation and data submission) should be encouraged (even if submission is by PHINMS)

22. Discussion: Event-related surveillance Symptoms may not be mentioned in CC ‘EXPOSURE TO CO’ was most common term in CC Our data indicate that once a problem is identified, patients or ED staff may refer to it in CC text and leave out actual symptoms (on which our syndrome classifications are based) Surveillance system must be flexible in order to incorporate terms related to events rather than symptoms (e.g., search for ‘SMOKE INHALATION’ may miss a CC of ‘NEAR OIL TANK EXPLOSION’)

23. Discussion: Event-related surveillance CC text may be influenced by media reports Not only ED staff but the patients also may use terminology being reported in news Searching for terms from news reports may help identify cases Locations, flight numbers, etc.

24. Conclusions Chief Complaint data from hospital EDs can provide valuable information regarding health hazard events Submitted daily (or with short delays) via syndromic surveillance systems, this data is more readily available than other data sources, like SPARCS (submitted after several months) Medical record numbers in ED data allow hospitals to trace patients for investigation or follow-up

25. Another example of event-related surveillance: heat exhaustionED syndromic data searched for key text strings in CC:'HEAT EXHAUSTION', 'HEAT STROKE', 'HEAT RELATED', 'OVER HEATED', 'HEAT EXPOSURE', 'HEAT CRAMP', 'HEAT TRAUMA', 'HEAT ILLNESS', 'HEAT DIZZY', 'FAINTED DUE TO HEAT', 'COLLAPED FROM HEAT', 'PASSED OUT FROM HEAT'