Quality of life of patients with complete loss of teeth and the psychometric properties of the OHIP-20 DG questionnaire. Part 3. Investigation of latent variables

Abstract

BACKGROUND: In the rehabilitation of patients with complete loss of teeth, an important aspect is the study of their quality of life (QL) as an indicator reflecting the effectiveness of treatment. AIM: Use latent variables and control their magnitude to control the development or suppression of symptoms in patients. MATERIAL AND METHODS: Within the framework of the modern theory of latent variables, the study examined the QL of patients with complete loss of teeth at various stages of dental orthopedic treatment. RESULTS: The average relative error of the forward and reverse conversion of the polytomic score indicators, i.e., latent variables, was 3.69%, which indicated a very high accuracy of measurements of latent variables. The QL estimates obtained by different methods were in good agreement with each other, and the Pearson correlation coefficients were 0.991, 0.999, and 0.982 before and after prosthetics. The characteristic curves of the questionnaire items were close to the experimental score indicators (p 0.05). The parameters of the latent variables at various stages of treatment were calculated using the KolmogorovSmirnov criterion, which showed that their distributions were normal, and the medians moves in different directions, which corresponded to an increase in QoL during treatment and adaptation. The interpretation of latent variables is proposed: i is the resistance (reserve level) of the body of the i-th patient before prosthetics or the effectiveness of treatment and adaptation after prosthetics; j presents the severity and intensity of pathogenic factors in the development of the j-th symptom, and Pij is the probability of the removal of the j-th symptom in the i-th patient. CONCLUSION: It has been established that by identifying and measuring latent variables, as well as controlling their magnitude, we can control the level of development or suppression of symptoms in patients.