Abstract

Background. Uncertainty in illness is a perceptual and cognitive state ranging from feelings of insecurity to complete ambiguity, characterized by its dynamic nature and accompanied by both positive and negative emotions. It is considered as a significant factor influencing the mental state and adaptation process of patients with chronic diseases. Valid instruments are required for the assessment of this phenomenon across diverse patient groups.

Objective. Adaptation and validation the Mishel Uncertainty in Illness Scale — MUIS-A (adult form) on the Russian sample of patients with malignant neoplasms and cardiovascular diseases.

Study Participants. 299 patients aged 18 to 85 years, including 247 diagnosed with cancer and 52 — with cardiovascular diseases.

Methods. Participants completed the following questionnaires: Mishel Uncertainty in Illness Scale (MUIS-A), COPE inventory, Self-efficacy Assessment Regarding Treatment Questionary, Beck's Anxiety and Depression Inventories (BAI, BDI). Data analysis was conducted using descriptive statistics, bifactor modeling ESEM, reliability assessment (GLB, Cronbach's alpha and McDonald's omega coefficients), comparative analysis (Welch's t-test), and correlation analysis (Pearson's correlation coefficient).

Results. The MUIS-A demonstrated sensitivity to differences in levels of uncertainty in illness across the studied groups. Thus, cancer patients turned to have higher uncertainty in illness. Structural analysis and factor inter-correlations suggest a construction with one common factor ("general uncertainty") including four specific factors ("ambiguity", "complexity", "inconsistency", "unpredictability"). Reliability of both common and specific factors ranged from moderate to high. Convergent validity was confirmed by significant correlations of the questionnaire factors with coping strategies, treatment-related self-efficacy, indicators of anxiety and depression.

Conclusions. The MUIS-A adapted in Russian is a reliable and valid instrument sensitive to the psychological state of patients with various illnesses. The MUIS-A can be used for comprehensive assessment of the mental state and adaptive processes in Russian-speaking patients with different diseases.