Disparity between objective and subjective ratings of quality of life in schizophrenia

Background

Poor objective (observer-rated) and subjective (patient-rated) quality of life has been repeatedly reported in schizophrenia. However, a disparity between objective and subjective ratings of quality of life in schizophrenia has been found in cross-sectional as well as longitudinal studies. Different clinical measures are determinants of observer-rated and patient-reported quality of life. Objective ratings of quality of life seem to be influenced by positive, negative and depressive symptoms, while patient-rated life satisfaction only by affective state. The purpose of the present study was to investigate the relationships between objective and subjective ratings of quality life, as well as the influence of psychopathology in them.

Materials and methods

Participants were 38 outpatients (23 men) with schizophrenia [mean age: 36.58 years (SD: 9.65, range: 20–57); mean level of education: 10.92 years (SD: 3.16, range: 6–16); mean duration of illness: 11.04 years (SD: 8.16, range: 1–36)]. Objective quality of life was rated with the Greek version of the Quality of Life Scale (QLS) [Interpersonal Relationships (IPR): extent of and capacity to form relationships; Instrumental Role Functioning (IRF): occupational, student, and housekeeper/parent roles; Intrapsychic Foundations (IF): sense of purpose, motivation, empathy, emotional interaction; Common Objects and Activities (COA): involvement with activities and objects in daily life (e.g., owning a car, reading a book)]. Subjective quality of life was assessed with the Greek version of the Short Form 36 Health Survey (SF-36) [Physical Summary Component: physical function, role limitations-physical, bodily pain, general health, and vitality; Mental Summary Component: role limitations-emotional, social functioning, and mental health] and the Health Status item from the EUROQoL-5D. Psychopathology was assessed with the five symptom dimensions from PANSS: positive, negative, cognitive, depression, and excitement symptoms.

Results

Significant intercorrelations were found among QLS subscales: IRP with IRF [r(38) = 0.65, p < 0.001], IF [r(38) = 0.85, p < 0.001], and COA [r(38) = 0.70, p <0.001]; IRF with IF [r(38) = 0.74, p < 0.001] and COA [r(40) = 0.62, p < 0.001]; IF with COA [r(38) = 0.74, p < 0.001]. Also, significant intercorrelations were found between subjective quality of life ratings: Physical Component-SF-36 with Mental Component-F-36 [r(38) = 0.76, p < 0.001] and Health Status [r(38) = 0.70, p = 0.001]; Mental Component-36 with Health Status [r(38) = 0.67, p = 0.001]. However, the four QLS subscales did not correlate with patient-reported quality of life ratings, except IRP with Mental Component-F-36 [r(38) = 0.42, p = 0.01]. Negative symptoms were significantly related with scores on the IPR [r(38) = -0.77, p = 0.001], IRF [r(38) = -0.46, p = 0.01], IF [r(38) = -0.70, p = 0.001], and COA [r(38) = -0.63, p = 0.001], whereas cognitive symptoms with scores on the IPR [r(38) = -0.37, p = 0.05] and IF [r(38) = -0.33, p = 0.05]. Mental Component was significantly correlated with positive symptoms [r(38) = -0.37, p = 0.05] and negative symptoms [r(38) = -0.39, p = 0.05], while Health Status was significantly associated with depression [r(38) = -0.32, p = 0.05]. No other significant relationships were found between quality of life scales and symptom ratings.

Discussion

Our data support the contention that patient-reported quality of life and observer-rated quality of life are not closely related and appear to have differing determinants in patients with schizophrenia. Objective quality of life was highly influenced by negative symptoms and mildly by cognitive symptoms, whereas subjective quality of life was only mildly correlated with positive and negative symptoms (Mental Summary Component) as well as depression (Health Status). Objective and subjective ratings of quality of life should be considered as separate and complementary outcome variables and utilized accordingly.