Evaluating the State of Hawaii Antimicrobial Resistance Project (SHARP) Database's Efficiency in Identifying Inpatient Methicillin Resistant Staphylococcus Aureus in Hawaii from 2009–2010

BACKGROUND:   A public health surveillance system collects, analyzes, interprets, and disseminates data regarding a health-related event. Public health surveillance can facilitate reducing morbidity and mortality associated with a health-related event. The State of Hawaii Antimicrobial Resistance Project (SHARP) is a surveillance system for antimicrobial resistance trends and resistant organisms. This study aims to evaluate SHARP’s ability to identify inpatient methicillin resistant Staphylococcus aureus (MRSA) in Hawaii from 2009–2010.

METHODS:   Automated antimicrobial susceptibility testing (AST) data are retrospectively collected by SHARP. Data are collected from the state’s 4 major clinical laboratories and comprise over 95% of AST data statewide. All S. aureus in the SHARP database tested against oxacillin were retrieved and compared with the 2010 minimum inhibition concentration (MIC) oxacillin resistance breakpoints determined by the Clinical and Laboratory Standards Institute.  We contracted Hawaii Health Information Corporation (HHIC) to link the SHARP dataset to their hospital discharge MRSA ICD9 coding data to provide missing data elements (e.g. admission and discharge dates).  

RESULTS:   For the time period of interest 57,739 S. aureus isolates were tested against oxacillin in SHARP. A total of 9,058 (16%) were identified as inpatient isolates. Of those, a total of 2,802 (31%) inpatient MRSA isolates were identified from 2009–2010. HHIC identified 3,434 inpatient MRSA cases with MRSA ICD9 codes from their database. Comparing the SHARP laboratory data with HHIC discharge data, there was only a 45% (n= 1,257) match of MRSA cases. 

CONCLUSIONS:   Periodic evaluation of existing surveillance systems, such as SHARP, is imperative to identify and address issues in quality, efficiency, and usefulness. We were unable to verify all inpatient MRSA cases in Hawaii using the SHARP database. Review of the SHARP MRSA data suggests that the incongruity between the two data systems may be related to SHARP not receiving all relevant result data from all laboratories, while HHIC data may contain potential ICD9 misclassification by providers at time of discharge. It is also possible that some specimen sources were misidentified in SHARP as originating from inpatients instead of outpatients or vice versa. Further evaluation and modification of SHARP will be required to ensure its usefulness and improve surveillance of antimicrobial resistant organisms in Hawaii.