Establishing minimal clinically important differences for the Quality of Life Instrument of Chronic Gastritis QLICD-CG(V2.0) based on distribution-based methods

BACKGROUND: To establish the lowest score reflecting meaningful changes from the perspective of patients is very important for explaining the results of patient reports. The measurement scale of quality of life in patients with chronic gastritis has been used in clinical practice, but the minimal clinically important difference (MCID) has not been worked out. In this paper, we use a distribution-based method to calculate the MCID of the scale QLICD-CG (Quality of Life Instruments for Chronic Diseases- Chronic Gastritis) (V2.0). METHODS: The QLICD-CG(V2.0) scale was used to evaluate the quality of life in patients with chronic gastritis. Since the methods for developing MCID were diverse and there was no uniform standard, we took MCID developed by anchor-based method as the gold standard, and compared the MCID of QLICD-CG(V2.0) scale developed by various distribution-based methods for selection. Standard deviation method (SD), effect size method (ES), standardized response mean method (SRM), standard error of measurement method (SEM) and reliable change index method (RCI) are given in the distribution-based methods. RESULTS: A total of 163 patients, with an average age of (52.37 ± 12.96) years old, were calculated according to the various methods and formulas given by the distribution-based method, and the results were compared with the gold standard. It was suggested that the results of the SEM method at the moderate effect (1.96) should be taken as the preferred MCID of the distribution-based method. And thus the MCID of the physical domain, psychological domain, social domain, general module, specific module and total score of the QLICD-CG(V2.0) scale were 9.29, 13.59, 9.27, 8.29, 13.49 and 7.86, respectively. CONCLUSIONS: With anchor-based method as the gold standard, each method in distribution-based method has its own advantages and disadvantages. In this paper, 1.96SEM was found to have a good effect on the minimum clinically significant difference of the QLICD-CG(V2.0) scale, and it is recommended as the preferred method to establish MCID.