Psychometric Evaluation of a Decision Quality Instrument for Treatment of Lumbar Herniated Disc

Study Design. Retrospective and prospective patient surveys and a physician survey using a sample from American Medical Association master file. Objective. To evaluate the performance of a new instrument designed to measure the quality of decisions about treatment of herniated disc. Summary of Background Data. There is growing consensus on the importance of engaging and informing patients to improve the quality of significant medical decisions, yet there are no instruments currently available to measure decision quality. Methods. The herniated disc-decision quality instrument (HD-DQI) was developed with input from clinical experts, survey research experts, and patients. The HD-DQI produces 2 scores each scaled to 0% to 100%, with higher scores indicating better quality: (1) a total knowledge score and (2) a concordance score (indicating the percentage of patients who received treatments that matched their goals). We examined hypotheses relating to the acceptability, feasibility, validity, and reliability of the instrument, using data from 3 samples. Results. The HD-DQI survey was feasible to implement and acceptable to patients, with good response rates and low missing data. The knowledge score discriminated between patients who had seen a decision aid or no decision aid (55% vs. 38%, P < 0.001) and between providers and patients (73% vs. 46%, P < 0.001). The knowledge score also had good retest reliability (intraclass correlation coefficient = 0.85). Most patients (78%) received treatments that matched their goals. Patients who received treatments that matched their goals were less likely to regret the decision than those who did not (13% vs. 39%, P = 0.004). Conclusion. The HD-DQI met several criteria for high-quality patient-reported survey instruments. It can be used to determine the quality of decisions for treatment of herniated disc. More work is needed to examine acceptability for use as part of routine patient care.