Sickness behavior and asthma-related quality of life (QoL) may be determinants of self-rated health in patients with asthma, according to a study published in PLoS One.
The 1-year longitudinal study sought to investigate levels of inflammatory cytokines, along with lung function, sickness behavior, and asthma-related QoL, to determine the role played by each variable in patient-reported outcomes. A total of 181 participants with allergic asthma, aged 18 to 64 years, were evaluated.
Sickness behavior was defined as a composite variable that included patients’ ratings of their energy, sleep, memory, fitness, and appetite, scored on a Likert scale from “very poor” (1) to “excellent, could not be better” (7). The scale was inverted to facilitate interpretation, with higher scores thus correlating to a greater degree of sickness behavior. To measure inflammatory cytokines, circulating levels of interleukin 5 (IL-5) and IL-6 were analyzed from plasma samples. Lung function, which was measured as forced expiratory volume in 1 second (FEV1), was assessed via spirometry. Self-rated health was evaluated via use of a questionnaire; asthma-related QoL was assessed using the mAQLQ (mini-Asthma Quality of Life Questionnaire).
A greater degree of sickness behavior and poorer asthma-related QoL were both associated with significantly poorer rated self-health (P <.001 for each). In men, both high and low levels of IL-6, as well as poorer lung function, were associated with significantly poorer self-rated health (P <.05 for each). Over the course of 1 year, improved asthma-related QoL was associated with better self-rated health in both men and women (P <.01). Moreover, if sickness behavior decreased, self-rated health was significantly improved, but only in women (P <.05).
Increased FEV1 in men was associated with significantly higher levels of IL-6 (P <.05), as well as significantly improved self-rated health (P <.05) and asthma-related QoL (P <.01) over the course of 1 year.
This study underscores the significance of subjectively perceived sickness behavior and asthma-related QoL, as well as lung function, as key factors in self-rated health in patients with asthma. The role played by inflammatory activation in patient-reported health outcomes among individuals with chronic inflammatory conditions warrants additional investigation.
Lodin K, Lekander M, Syk J, Alving K, Petrovic P, Andreasson A. Longitudinal co-variations between inflammatory cytokines, lung function and patient reported outcomes in patients with asthma. PLoS One. 2017;12(9):e0185019.