In 122 COPD patients, mean age 60.8 ± 10.3 years, 52% female, and mean forced expiratory volume in 1 s (FEV1) 41.1 ± 17.6%pred, we assessed body mass index, post bronchodilator FEV1, exercise capacity, depressive symptoms with the Hospital Anxiety and Depression Scale, and type D with the Type D Scale.
The first regression model aimed to identify the contribution of the following explanatory variables: presence of pain, a history of falls, number of comorbidities, self-perception of health, level of stress, cognitive capacity, depressive symptoms, and functional capacity (measured by gait speed, Timed Up and Go test, and Sit-to-Stand test).
An extract from Sullivan & Youngner's (1994) review demonstrates how the (emotional) symptoms of depression (in bold) might correlate with deficits in the cognitive (understanding, appreciation and reasoning) components of mental capacity: 'Depressive helplessness produces an underestimation of one's possible effectiveness in the face of serious illness.
Each model was adjusted stepwise for sex, age, education, functional capacity, and depressive mood (Table 4).
The model was adjusted stepwise for sex, age, education, functional capacity, and depressive mood.
A significant interaction effect indicated a difference in the association between changes in functional capacity and depressive symptoms depending on the level of functional capacity at baseline.
Each model was adjusted for known confounders, with each predictor variable entered into each successive model accordingly, including sex, age, education, functional capacity, and depressive mood.
The association between LS and cognitive ability was attenuated when adjusted for functional capacity and depressive symptoms, and the latter two factors seemed to influence LS stronger than cognitive abilities.
Factors such as stroke, dementia, functional capacity, and depressive mood, known to influence or be influenced by cognitive performance as well as LS, were included as confounders in the model.
Examples of such factors could be burden of symptoms, which has been shown to explain 14% of the variance in LS, 1 functional capacity, and depressive mood. 1, 2 From a medical point of view, however, knowledge about the associations between cognition and LS might offer additional tools in an attempt to maintain LS in this patient group.
We will check for possible baseline differences between the two conditions in background variables (e.g., age, sex, and ethnic background, cognitive capacities) and depressive symptoms.
