The impact of information disclosure on quality of care in HMO markets

To examine the impact of voluntary information disclosure on quality of care in Health Maintenance Organization (HMO) markets in the USA.

Commercial HMOs that collected a set of standardized quality meausures, Health Plan Employer Data and Information Set (HEDIS), between 1997 and 2000 in the USA (1062 HMO-years). After collecting the HEDIS data, some HMOs disclosed their HEDIS-quality scores to the public (disclosing HMOs), whereas some HMOs declined to disclose the information (non-disclosing HMOs).

A secondary data analysis based on 4 years of quality scores of HMOs. The study uses non-disclosing plans as a control group. A treatment-effects model is used to address a potential bias associated with voluntary disclosure decisions by HMOs.

The study focuses on 13 HEDIS clinical indicators. On the basis of these indicators, a plan-level composite score and four domain scores were constructed. The four domains are childhood immunizations, treatments/exams for chronic conditions, screening tests and maternity services.

Public disclosure leads to an increase of 0.72 composite score units, which corresponds to ∼7% points in original quality scale (0-100%). The degree of quality improvement differed by the type of services.

Public release of quality information had a significant and positive effect on quality in HMO markets during the earlier years of the voluntary disclosure program; however, the improvement was not universal across all quality measures.