THE USE OF ELECTRONIC MEDICAL RECORDS BASED ON A PHYSICIAN DIAGNOSIS OF ASTHMA FOR COUNTY WIDE ASTHMA SURVEILLANCE

Allegheny County (AC) has limited information on asthma morbidity. In order to improve upon the sensitivity of asthma, a cross sectional study from January 1, 2002 through December 31, 2005 was conducted to determine whether the data received for emergency room visits from a large regional medical center might be a good predictor for quantifying asthma cases for surveillance. An electronic medical record (EMR) abstract using the Council for State and Territorial Epidemiology (CSTE) Asthma Surveillance case definition of an ICD 9 coded physician diagnosis for primary and secondary asthma (n= 18,284), and primary asthma (n = 5,100) were used to define asthma. The analysis used data from a subset of six hospitals from a large regional medical center covering approximately 60% of adult ED visits in AC that use electronic data for reporting. A secondary analysis of the physician diagnosed primary asthma cases (n= 180) was applied against the CSTE Clinical and Laboratory case definition. Statistical software was used to validate these data abstracted from the EMR. Once these data were validated for accuracy, a fourth dataset of any primary asthma emergency room visits (n= 10,183) were used to test the relationship between asthma morbidity and exposure to ozone. Recent studies have linked asthma hospitalizations in several cities to ozone action days. However, data on the effects of ozone as they relate to asthma emergency room (ER) visits have not been well studied. Electronic medical records from the six hospitals representing the large metropolitan medical center in Allegheny County, PA were obtained on individuals with asthma based on the ICD-9 discharge diagnosis of (493.0-493.9) for the respective time period. Data on ozone, PM2.5, and temperature were obtained for same period. A case crossover methodology using conditional logistic regression as the statistical estimator was conducted to assess the relationship between levels of ozone and PM 2.5 and increases in asthma ER visits. A time stratified sampling strategy was employed assuming a 3:1 case-control ratio.A total of 6,979 individuals were included in the study, with a mean age of 39.25 ±21.0. The mean ozone exposure for this period was 40.6 ppb (range: 0-126). The effect estimates for year-round data was greatest for a 2-day lag adjusted for temperature (OR= 1.02 (95% CI= 1.01-1.04) (p<.05). For each 10-ppb increase in 24-hour maximum ozone, a 2% increase was noted in asthma ER visits. These results indicate that asthma ED visits may be an additional source of information for use in environmental public health tracking