Distribution of Central Line Associated Bloodstream Infections in Washington State, 2009 - 2013

BACKGROUND:  Healthcare-associated infection public reporting of central line associated bloodstream infection (CLABSI) focused largely on acute-care hospital intensive care units (ICU).  However, more CLABSI cases occur outside ICUs.  Washington State requires acute care hospitals to report certain infections through CDC’s National Healthcare Safety Network (NHSN).  To ensure credibility of hospitals’ CLABSI surveillance and reporting, we developed a statistically and epidemiologically sound validation process.  Our process enforces acceptable CLABSI reporting sensitivity and specificity, and lets us estimate the total burden of CLABSI using both NHSN surveillance definitions and broader clinical definitions.

METHODS:  CLABSI reporting began in August 2008 for ICUs.  Annual validation, including on-site medical record review visits, was conducted from 2010 onward and each visit assesses a 1-2 year period.  Sensitivity and specificity are enforced using acceptance sampling per International Standards Organization (ISO) 2859.  In addition to a records sample from positive blood culture cases, all cases identified by ICD-9 codes 999.31 or 999.32 and our NHSN records were considered.  Capture-recapture (Lincoln-Petersen) is used to estimate total CLABSI burden, both in-hospital and present-on-admission (POA).

RESULTS:  All 65 reporting hospitals received at least one validation visit in 2010-2013.  In total, 2,108 records were reviewed; 1,340 for positive blood cultures and 768 for ICD-9 codes.  Among blood culture records, 166 CLABSI were identified.  Among ICD-9 records, 409 (53.3%) also met NHSN CLABSI criteria.  Hospitals reported 145 CLABSI attributable to an ICU during the reviewed period.  We identified 15 previously unreported ICU CLABSI (12 by blood culture records), and two misclassified cases.  The total burden of CLABSI in Washington State is estimated between 2,250 to 3,650 cases per year, with approximately 10.9-11.9% hospital-associated attributable to an ICU; 20.9-21.2% hospital-associated attributable to lower-acuity inpatient areas; and 67.2-67.9% POA.

CONCLUSIONS:  ISO 2859 proved efficient to assess sensitivity and specificity.  Validation findings empirically supported expansion of CLABSI reporting to include all hospital inpatient areas.  This expansion became law in August 2013.  POA cases represent an even greater number in Washington State.  The proportion of POA cases attributable to care outside hospitals (e.g. dialysis clinics, and infusion or home care services) is unknown but appears higher than the proportion due to readmission following recent hospitalization.  The department is recommending in 2014 that its authority be expanded to include facilities beyond acute-care hospitals in public reporting.