Asthma expectations predict symptoms over time: a longitudinal cohort study

Abstract

Background: Placebo and nocebo promote physical modifications by creating the expectation of a change through a primer (e.g., a fake pill). Every person who receives a diagnosis develops his/her expectations about the course of the disease. This is the concept of “Illness Expectation” (IE), a cognitive schema that defines the future-oriented beliefs about the illness and the symptoms of someone with a chronic disease. These beliefs are both explicit and implicit, and they could be characterized by different degrees of rigidity.

Aims: The study aims to test the hypothesis that IEs affect illness symptoms in asthma.

Method: Three-hundred twelve participants with asthma were assessed three times over the course of 6 months, for asthma symptoms (Asthma Control Test), respiratory values (FEV1 through spirometer), and illness expectations, by using the previously validated “Illness Expectation Test”, which assessed both explicit and implicit expectations. The predictive values of illness expectations over asthma symptoms and respiratory parameters were measured with latent growth modeling and linear regressions.

Results: Longitudinal data analysis suggests a strong predictive value of explicit expectations over self-reported asthma symptoms (β=-.50, se=.21, p=.01). Implicit expectations showed a similar pattern, with a trend toward significance (β=-.014, se=.008, p=.09). Furthermore, the expectations of improvement or worsening of the symptoms over time strongly predicted changes in respiratory values (β=.51, se=.11, p=.001).

Conclusions: These results confirm the relevance of illness expectations in asthma progression and suggest a high potential for mind/body interventions.