Development and Validation of an Instrument to Measure Health-Related Out-of-Pocket Costs: The Cost for Patients Questionnaire.

Abstract Objective The growth of healthcare spending is a major concern for insurers and governments but also for patients whose health problems may result in costs going beyond direct medical costs. To develop a comprehensive tool to measure direct and indirect costs of a health condition for patients and their families to various outpatient contexts. Methods We conducted a content and face validation including results of a systematic review to identify the items related to direct and indirect costs for patients or their families and an online Delphi to determine the cost items to retain. We conducted a pilot test-retest with 18 naive participants and analyzed data calculating intraclass correlation and kappa coefficients. Results An initial list of 34 items was established from the systematic review. Each round of the Delphi panel incorporated feedback from the previous round until a strong consensus was achieved. After 4 rounds of the Delphi to reach consensus on items to be included and wording, the questionnaire had a total of 32 cost items. For the test-retest, kappa coefficients ranged from −0.11 to 1.00 (median = 0.86), and intraclass correlation ranged from −0.02 to 0.99 (median = 0.62). Conclusions A rigorous process of content and face development was implemented for the Cost for Patients Questionnaire, and this study allowed to set a list of cost elements to be considered from the patient’s perspective. Additional research including a test-retest with a larger sample will be part of a subsequent validation strategy.