Intraindividual construct validity of anxiety, depression, fatigue, and irritability in chronic hepatitis C: a daily process study
Mooney, Scott R.
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Anxiety, depression, fatigue, and irritability are common symptoms in patients who are chronically infected with the hepatitis C virus (HCV). Review of the recent empirical literature suggests that these symptoms are highly inter-correlated in HCV patients, but are not related to level of liver enzymes or amount of liver scaring. Given evidence that psychological distress may be related to poorer antiviral treatment outcome in HCV patients because of poor treatment compliance and dose reduction or cessation, closer examination of the functional relationships between these symptoms in HCV patients is needed in order to improve the potential benefits from HCV treatment, and to assist in psychological and pharmacological treatment planning for anxiety, depression, fatigue and irritability. Using a multivariate replicated single-subject repeated measures design, this study examined the intraindividual, over-time construct validity of anxiety, depression, fatigue, and irritability in two adult patients who were chronically infected with HCV and who were experiencing clinically significant depression and/or anxiety. Daily ratings completed over 87 and 90 days were analyzed with confirmatory dynamic factor analysis (CDFA), confirmatory P-technique factor analysis (CPTFA), and dynamic time series regression (DTSR). For both cases, CDFA and CPTFA analyses indicated the intraindividual, over time daily- and phase-state trajectory (over time trend) dimensional structures of anxiety, depression, fatigue, and irritability were empirically distinct. However, DTSR analyses provided mixed support for the predicted relationships between certain types of stressful events and cognitions within the four types of psychological distress. Findings from the present study have implications for the clinical assessment and treatment of these symptoms and compliance with antiviral medical treatment in HCV patients.