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ISDS 2016 Conference Abstracts

ICD-9 code reporting among patients from the 
Minnesota SARI surveillance program
Andrea Steffens*1, Hannah Friedlander2, Kathy Como-Sabetti2, Dave Boxrud2, 
Sarah Bistodeau2, Anna Strain2, Carrie Reed1, Ruth Lynfield2 and Ashley Fowlkes1
1Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA; 2Minnesota Department of Health, Saint Paul, MN, 
USA

Introduction
The ICD-9 codes for acute respiratory illness (ARI) and 

pneumonia/influenza (P&I) are commonly used in ARI surveillance; 
however, few studies evaluate the accuracy of these codes or the 
importance of ICD-9 position. We reviewed ICD-9 codes reported 
among patients identified through severe acute respiratory infection 
(SARI) surveillance to compare medical record documentation with 
medical coding and evaluated ICD-9 codes assigned to patients with 
influenza detections.

Methods
The Minnesota Department of Health (MDH) conducted SARI 

surveillance at three hospitals. All hospitalized patients with 
submission of a physician-ordered upper respiratory specimens  
(e.g., sputum, throat or nasopharyngeal swabs) were enrolled.  
A medical chart review was conducted to identify those meeting 
SARI criteria, defined as patients admitted to an inpatient ward with 
new onset of respiratory symptoms or acute exacerbation of chronic 
respiratory conditions. Enrolled patients who did not meet the SARI 
criteria were categorized as non-SARI. Residual material from the 
upper respiratory specimens were submitted to MDH for influenza 
testing by RT-PCR. Demographic and clinical data, including up 
to eight ICD-9 codes, were collected through the medical record 
review. Patients with an ICD-9 code indicating ARI (460 to 466) 
or P&I (480 to 488) were defined as having an ARI/P&I code. We 
compared the frequency of ARI/P&I codes by SARI clinical criteria 
and influenza detection and evaluated the position of the reported  
ARI/P&I code.

Results
From May 2013 through August 2015, we enrolled 5,950 

patients, of which 4,449 (75%) met SARI criteria and 1501 did not  
(non-SARI). An ARI/P&I code in any position was found in 61% 
(2705) of SARI vs. 16% (241) of non-SARI patients (odds ratio [OR] 
8.1, 95% confidence interval [CI] 7.0-9.4); an ARI/P&I code in the 
first position was found in 40% of SARI vs 7% of non-SARI patients 
(OR=8.6, 95% CI 7.0-10.5). Among SARI patients with at least one 
ARI/P&I code, 66% had their first or only ARI/P&I code in the 1st 
position, 25% in the 2nd position, and 6% in the 3rd position. For 
identification of SARI, sensitivity/specificity was 61%/84% for ARI/
P&I codes in any position and 40%/93% for ARI/P&I codes in the 1st 
position. Among SARI patients, codes for pneumonia (486) and acute 
bronchiolitis (466.11, 466.19) were commonly reported. The most 
frequent codes among SARI patients without an ARI/P&I code were 
fever (780.6), acute respiratory failure (518.81), and asthma (493.92) 
(Table). Influenza was detected among 8% (351) of SARI patients. 
An ARI/P&I code in any position was more common in influenza-
positive vs. influenza-negative SARI patients (77% vs 59%, OR 2.4, 
95% CI 1.8-3.1). An ARI/P&I code in the 1st position was slightly 
more common in influenza-positive vs -negative patients though not 
significant (44% vs 40%).

Conclusions
Among patients from whom a respiratory specimen was collected, 

administrative data identified those meeting SARI with moderate 
sensitivity and high specificity, and with lower sensitivity but greater 
specificity when limited to the 1st ICD-9 position. Pneumonia and 
acute bronchiolitis ICD-9 codes were frequent ARI/P&I codes among 
SARI patients. Further investigation is needed to determine the value 
of including additional ICD-9 codes, such as respiratory distress and 
acute asthma exacerbation, in identifying SARI.

Most frequently reported ICD-9 codes among SARI, non-SARI and influenza 
test-positive patients with no ARI/P&I codes.

Keywords
ICD-9; Influenza; Hospitalized; Respiratory

*Andrea Steffens
E-mail: vqg1@cdc.gov

Online Journal of Public Health Informatics * ISSN 1947-2579 * http://ojphi.org * 9(1):e105, 2017