Do We Need This Blood Culture?

Objectives: This study describes blood culture collection rates, results, and microbiology laboratory charges for 4 leading pediatric inpatient diagnoses (asthma, bronchiolitis, pneumonia, and skin and soft tissue infection [SSTI]) in low-risk patients.

Methods: This retrospective cohort study was conducted at an urban, academic, quaternary children’s hospital. The study period was from January 1, 2011, to December 31, 2011. Inclusion criteria were as follows: 6 months to 18 years of age and primary diagnosis of asthma (International Classification of Diseases, Ninth Revision [ICD-9] codes 493.91–493.92), bronchiolitis (ICD-9 codes 466.11 and 466.19), SSTI (ICD-9 codes 680.00–686.99), or pneumonia (community-acquired pneumonia; ICD-9 codes 481.00–486.00). Patients with complex chronic conditions were excluded. Data were collected via administrative billing data and chart review. Descriptive statistics were performed; χ² tests were used for categorical variables, and nonparametric tests were used for continuous variables because of non-normal distributions.

Results: Administrative data review included 5159 encounters, with 1629 (32%) inpatient encounters and 3530 (68%) emergency department/outpatient encounters. Twenty-one percent (n = 343) of inpatient encounters had blood cultures performed, whereas 3% (n = 111) of emergency department/outpatient encounters had blood culture testing performed. Inpatient blood culture utilization varied according to diagnosis: asthma, 4%; bronchiolitis, 15%; pneumonia, 36%; and SSTI, 46%. Charts were reviewed for all 343 inpatients with blood culture testing. Results of all the blood cultures obtained for asthma and bronchiolitis admissions were negative, with 98% and 99% negative or false-positive (contaminant) for SSTI and community-acquired pneumonia, respectively. The approximate financial impact of blood culture utilization (according to gross microbiology laboratory charges) approximated $100 000 over the year for all 4 diagnoses.

Conclusions: There was a high rate of negative or false-positive blood culture results for these common inpatient diagnoses. In addition, there was a low rate of clinically significant true-positive (pathogenic) culture results. These results identify points of potential blood culture overutilization.