Effect of CDC adjustment of state-reported data on community water fluoridation statistics

Advancing community water fluoridation (CWF) coverage is a national health objective. The Centers for Disease Control and Prevention began adjusting state-reported data to calculate CWF coverage in 2012, and then modified methods in 2016. We evaluate improvements attributable to data adjustment and implications for interpreting trends. To assess adjustment, we compared the percentage deviation of state-reported data and data adjusted by both methods to the standard estimated by the U.S. Geological Survey. To assess effects on estimated CWF trends, we compared statistics calculated with data adjusted by each method. The 2016 method outperformed on all points of evaluation. The CWF national objective measure (percentage of community water system population receiving fluoridated water) was negligibly affected by method. Percentage of US population receiving fluoridated water was lower with the 2016 method versus the 2012. Adjustment of state-reported data improved overall quality of CWF coverage measures and had minimal impact on key measures.