Evaluating the Sickle Cell Data Collection Program’s Administrative Case Definition for Adults with Sickle Cell Disease (Preprint)

BACKGROUND Sickle cell disease (SCD) was first recognized in 1910 and identified as a genetic condition in 1949. However, there is not a universal clinical registry that can be used currently to estimate prevalence. The Sickle Cell Data Collection (SCDC) program, funded by the Centers for Disease Control and Prevention, funds state-level grantees to compile data within their states from various sources including administrative claims to identify individuals with SCD. The performance of the SCDC administrative claims case definition has been validated in a pediatric population with SCD, but it has not been tested in adults. OBJECTIVE The objective of our study is to evaluate the discriminatory ability of the SCDC administrative claims case definition to accurately identify adult SCD cases using Medicaid insurance claims data. METHODS Our study uses Medicaid claims data in combination with hospital-based medical record data from the Alabama (AL), Georgia (GA), and Wisconsin (WI) SCDC programs to identify individuals 18 years of age or older meeting the SCDC administrative claims case definition. In order to validate this definition, our study included only those subjects that were identified in both Medicaid and the partnering clinical institution. We used clinical laboratory tests and diagnostic algorithms to determine the true SCD status of this subset. Positive predictive values (PPV) are reported overall and by state under several scenarios. RESULTS There were 1,219 individuals (354 from AL and 865 from GA) who were identified using a 5-year time period. The 5-year time period yielded a PPV of 88.4% (91% for data from AL, 87% for data from GA), when only using data with lab-confirmed (gold standard) cases as true positives. With a narrower time period (3-year period) and data from three states (AL, GA and WI), there were a total of 1,432 individuals from these states included in our study. The 3-year time period PPV overall was 89.4% (92%, 93% and 81% for data from AL, GA and WI respectively) when only considering lab-confirmed cases as true cases. CONCLUSIONS Adults identified as having SCD from administrative claims data using the SCDC case definition have a high probability of truly having the disease. Administrative claims are thus a valuable data source to identify adults with SCD in a state and understand their epidemiology and healthcare service utilization.