Many enteric pathogens disproportionately infect children. Hospital discharge data can provide information on severe infections, including cost. However, the diagnosis must be recorded on the discharge record and coded accurately. We estimated the rate of underascertainment in hospital discharge data among children with culture-confirmed Campylobacter, Salmonella, and Escherichia coli O157 infections using linked laboratory and hospital discharge data from an integrated health care organization. We reviewed the International Classification of Diseases, 9th and 10th Revisions, Clinical Modification (ICD-9/10-CM) diagnosis codes on each patient's discharge record. We determined the percentage of patients who had a pathogen-specific diagnosis code (for Campylobacter, Salmonella, or E. coli O157) or nonspecific gastroenteritis code. We included the first admission or positive test and calculated the number of days between specimen submission (outpatient ≤7 days before admission or inpatient) and hospital discharge. Of 65 hospitalized children with culture-confirmed Campylobacter (n = 30), Salmonella (n = 24), or E. coli O157 (n = 11) infections, 55% had that pathogen-specific diagnosis code listed on the discharge record (79% Salmonella, 54% E. coli O157, 37% Campylobacter). The discharge records of the 35 children with a specimen submitted for culture ≥3 days before discharge were 16 times more likely to have a pathogen-specific diagnosis than the records of the 30 children with a specimen submitted <3 days before discharge (83% vs. 23%; odds ratio 15.9, 95% confidence interval: 4.7-53.8). Overall, 34% of records of children with culture-confirmed infection had ≥1 nonspecific gastroenteritis code (Campylobacter 43%, Salmonella 29%, E. coli O157 18%), including 59% of those for children without a pathogen-specific diagnosis (Campylobacter 63%; Salmonella 60%; E. coli O157 40%). This study showed that hospital discharge data under-ascertain enteric illnesses in children even when the infections are culture confirmed, especially for infections that usually have a short length of stay.
Keywords: Campylobacter; E. coli O157; Salmonella; enteric illness; hospitalizations.