Validation of the generic medical interview satisfaction scale: the G-MISS questionnaire

BACKGROUND Patients have about seven medical consultations a year. Despite the importance of medical interviews in the healthcare process, there is no generic instrument to assess patients' experiences in general practices, medical specialties, and surgical specialties. The main objective was to validate a questionnaire assessing patients' experiences with medical consultations in various practices. METHOD The G-MISS study was a prospective multi-center trial that enrolled patients from May to July 2016. A total of 2055 patients were included from general practices, medical specialties, and surgical specialties. Patients filled out a questionnaire assessing various aspects of their experience and satisfaction within 1 week after their medical interview. The validation process relied on item response theory. Internal validity was examined using exploratory factorial analysis. The statistical model used the root mean square error of approximation, confirmatory fit index, and standard root mean square residual as fit indices. Scalability and reliability were assessed with the Rasch model and Cronbach's alpha coefficients, respectively. Scale properties across the three subgroups were explored with differential item functioning. RESULTS The G-MISS final questionnaire contained 16 items, structured in three dimensions of patients' experiences: "Relief", "Communication", and "Compliance". A global index of patients' experiences was computed as the mean of the dimension scores. All fit indices from the statistical model were satisfactory (RMSEA = 0.03, CFI = 0.98, SRMR = 0.06). The overall scalability had a good fit to the Rasch model. Each dimension was reliable, with Cronbach's alpha ranging from 0.73 to 0.86. Differential item functioning across the three consultation settings was negligible. Patients undergoing medical or surgical specialties reported higher scores in the "Relief" dimension compared with general practice (83.0 ± 11.6 or 82.4 ± 11.6 vs. 73.2 ± 16.7; P < .001). A consultation shorter than 5 min correlated with low patient satisfaction in "Relief" and "Communication" and in the global index, P < .001. CONCLUSIONS The G-MISS questionnaire is a valid and reliable questionnaire for assessing patients' experiences after consultations with general practitioners, medical specialists, and surgical specialists. The multidimensional structure relies on item response theory and assesses different aspects of patients' experiences that could be useful in clinical practice and research settings.