You may notice that disease case counts sometimes change over time and local numbers sometimes differ from state reports for the same time period. The reasons involve state and local systems used to report, track and de-duplicate data.
State review. Case counts most often change over time for chronic reportable diseases, those that stay with a patient for years or even a lifetime. In these cases, health care providers or labs in different counties may report the same patient’s illness to different local health departments. This commonly happens when a patient travels to see a specialist or lives near the border of two counties, such as in Santa Maria, and gets health care in both. While each local health department only has access to their own data and cannot see this duplication, the state department of public health reviews cases from all counties and de-duplicates cases reported in multiple jurisdictions. This review leads to revised local numbers, often a year or more after initial reporting.
Local review. In other cases, numbers may change after local review. For example, state reports on opioid deaths are based on ICD-10 codes. Locally, our epidemiologist also closely reviews death certificates and specific information sources (such as coroner’s toxicology reports) and may identify additional cases through this review. In a common example, a death may be coded as a cardiac arrest, when in fact the cardiac arrest was caused by opioid overdose. This review is important in understanding the local epidemiology of an illness or injury, and is particularly relevant given SLO County’s relatively small population.