The Formulation of Minimal Clinically Important Differences in the Quality of Life Instrument for Patients with Chronic Renal Failure (QLICD-CRF) Based on Combinations of Anchor-Based and Distribution-Based Methods

Abstract

Background Chronic renal failure is global problem and represents a major cause of morbidity and mortality. Studies of quality of life in patients with chronic renal failure can be helpful to improve patient survival rates. The minimal clinical important difference (MCID) is a score that reflects the effect of patient treatment or nursing care. Doctors or researchers use this factor to assess the validity of results, and this information reflects the combined importance of the patient's opinion and the doctor's explanation.Methods Patients diagnosed with chronic renal failure and able to read and understand the questionnaires at the First Affiliated Hospital of Kunming Medical University were included in this study and completed the questionnaires independently. Using the anchor-based method and the distribution-based method, the MCIDs of the QLICD-CRF were calculated based on the data from 164 valid questionnaires at the time of admission and 111 valid questionnaires at discharge. The medians of patients' quality of life scores calculated using the anchor-based method were referred to as MCIDs based on the anchor-based method, whereas the results calculated based on effect size (ES), standard error of measurement (SEM) and reliable change index (RCI) were referred to as MCIDs based on the distribution-based method. Then, the final results were calculated according to the weight of the calculation obtained using several methods. Results MCIDs of the physical domain (PHD), psychological domain (PSD), social domain (SOD), core/general domain (CGD), specific domain (SPD) and the total score (TOT) of the QLICD-CRF were 10, 9, 8, 7, 8 and 7, respectively. Conclusion Calculations of MCIDs of QLICD-CRF scores could compensate for insufficient P-values; thus, the interpretation of the outcomes in quality of life studies could be more objective and specific.