Data Collection

For some HEDIS measures, HMOs can choose one of two ways to collect their data. If an HMO chooses the administrative method, the data are collected from the HMO’s claims database to identify cases and compute the HEDIS measures. If an HMO uses the hybrid method, cases are first identified using the claims database, then a registered nurse does reviews of medical charts to find additional information about the HEDIS measure. In the tables that follow, measures collected using the administrative method are labeled Administrative and measures collected using the hybrid method are labeled Admin+Chart Review. The hybrid method takes longer and costs more, but the reported values for HEDIS measures are usually more accurate than when HMOs use the administrative method. Therefore, differences in HMOs may be because the HMOs differ in quality, OR because the HMOs collected data using different methods. Whenever possible, comparisons should only be made between HMOs that used the same data collection method for a given variable. In general, administrative rates will be lower than hybrid rates.

Missing Data

Some variables have a “Not Reported” or a “Not Applicable” designation. “Not Reported” means that the HMO chose not to report a rate for that measure. This could be because there were significant problems with the data. A “Not Applicable” rate means that the sample size for that measure was too small (less than 30) to calculate a valid rate. All “Not Reported” and “Not Applicable” designations are governed by NCQA reporting rules, and do not reflect the overall quality of care.