Psychometric Properties of the Consumer Assessment of Health Plans Study (CAHPS) 2.0 Adult Core Survey

Published in: Health Services Research, v. 38, no. 6, pt. 1, Dec. 2003, p. 1509-1527

Posted on RAND.org on December 31, 2002

by J. Lee Hargraves, Ron D. Hays, Paul Cleary

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OBJECTIVE: To estimate the reliability and validity of survey measures used to evaluate health plans and providers from the consumer's perspective. DATA SOURCES: Members (166,074) of 306 U.S. health plans obtained from the National CAHPSs Benchmarking Database 2.0, a voluntary effort in which sponsors of CAHPS surveys contribute data to a common repository. STUDY DESIGN: Members of privately insured health plans serving public and private employers across the United States were surveyed by mail and telephone. Interitem correlations and correlations of items with the composite scores were estimated. Plan-level and internal consistency reliability are estimated. Multivariate associations of composite measures with global ratings are also examined to assess construct validity. Confirmatory factor analysis is used to examine the factor structure of the measure. FINDINGS: Plan-level reliability of all CAHPSs 2.0 reporting composites is high with the given sample sizes. Fewer than 170 responses per plan would achieve plan-level reliability of .70 for the five composites. Two of the composites display high internal consistency (Cronbach's alpha 45.75), while responses to items in the other three composites were not as internally consistent (Cronbach's alpha from .58 to .62). A five factor model representing the CAHPSs 2.0 composites fits the data better than alternative two- and three-factor models. CONCLUSION: Two of the five CAHPS s 2.0 reporting composites have high internal consistency and plan-level reliability. The other three summary measures were reliable at the plan level and approach acceptable levels of internal consistency. Some of the items that form the CAHPS 2.0 adult core survey, such as the measure of waiting times in the doctor's office, could be improved. The five-dimension model of consumer assessments best fits the data among the privately insured; therefore, consumer reports using CAHPS surveys should provide feedback using five composites.

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