Evaluation of a Local Reportable Disease Surveillance System — Marin County, California, 2012-2013

BACKGROUND:   Reportable disease surveillance systems allow local health departments to monitor and react to a wide range of communicable diseases among its population.  In 2011, the California Department of Public Health implemented California Reportable Disease Information Exchange (CalREDIE), a statewide Internet-based disease reporting application. Our objective was to evaluate the reportable disease surveillance system, including the use of CalREDIE, in Marin County, California in 2012 and 2013.

METHODS:   The surveillance system was evaluated based on attributes from the CDC’s 2001 Updated Guidelines for Evaluating Surveillance Systems.  Stakeholders were engaged in formative interviews and standardized questionnaires to assess surveillance system simplicity, stability, flexibility and acceptability. We focused the quantitative evaluation on pertussis, salmonella and chlamydia.  Analyses of paper-based case reports and CalREDIE records from 2012-2013 evaluated data quality and timeliness.  We measured completeness of key data fields; compared case report forms with CalREDIE records for a sample of reported cases; and calculated median times for key surveillance system steps.

RESULTS:   Stakeholder questionnaires (N=8) suggest that the system meets its objectives (71% agreed or strongly agreed).  Fifty-seven percent agreed that CalREDIE is easy to use.  Data entry takes time from other duties (86%), indicating low acceptability.  All stakeholders agreed that the system relies on key staff, affecting stability, and 67% agreed that it does not adapt well to disease surges, affecting flexibility.  Analyses of case report and CalREDIE data of pertussis (N=138), salmonella (N=52) and chlamydia (N=866) cases indicate date of birth and sex fields were complete (>98% for all diseases) and consistent between the sources (>94% for all diseases).  Race and ethnicity fields in CalREDIE were less complete (36% - 54% and 30% to 56%, respectively). Consistency of disease onset and specimen collection dates between case reports and CalREDIE records varied by disease (concordant fields ranging from 64%-90% and 35%-87%, respectively).  The median time interval from receiving the report to CalREDIE data entry was 2 days for pertussis, 0 days for salmonella and 7.5 days for chlamydia.

CONCLUSIONS:   The reportable disease surveillance system in Marin County, California adequately meets its objectives and accomplishes timely detection of reportable diseases, although it demonstrates limited stability and flexibility.  Completeness and accuracy of CalREDIE records differed across variables and diseases.  Additional training to surveillance system staff may enhance the ease of using CalREDIE.  Data quality, flexibility and stability could be improved with the refinement of local protocols to standardize data entry.