Dyslipidemia is a risk factor for uncontrolled asthma and is an independent risk factor for future asthma exacerbations, according to study findings published in Journal of Allergy and Clinical Immunology: In Practice.
Long-term studies of the relationship between dyslipidemia, asthma phenotypes, and future asthma exacerbations (AEs) are scarce, and the underlying mechanisms linking asthma and dyslipidemia are unclear. Investigators therefore conducted a 1-year observational cohort study of patients with asthma, with and without dyslipidemia, to investigate these relationships. Outcomes of interest included severe exacerbations (ie, those requiring a hospital visit or corticosteroids) and moderate to severe exacerbations (ie, those requiring a controller prescription or increase in ICS dose).
The study enrolled adult participants with stable asthma from a hospital in Sichuan, China, from June 2015 to August 2019. At baseline, information was collected from participants via a questionnaire, lung function testing, blood testing, and allergen skin-prick tests, and patients’ asthma phenotypes were identified. Participants were then divided into 2 cohorts according to their dyslipidemia status. Those in the dyslipidemia group (DLG) had abnormal levels of at least 1 of the following: triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), or high-density lipoprotein cholesterol (HDL-c); those in the normal lipidemia group (NLG) had normal levels of the 4 lipids. Exacerbations were tracked via regular follow-up throughout the study’s 1-year period.
A total of 477 patients (mean [SD] age, 45.83 [13.80] years; 64.8% female) with serum lipids data available were included in the analysis, including 259 patients in the normal lipid group and 218 in the dyslipidemia group. In the dyslipidemia cohort, 99 (20.8%), 158 (33.1%), 106 (22.2%), and 29 (6.1%) participants had dyslipidemia due to abnormal TG, TC, LDL-c, and HDL-c, respectively.
The investigators found that the dyslipidemia group had a higher proportion of patients with uncontrolled asthma compared with the NLG (NLG vs DLG: 21.3% vs 32.1%, P =.007, q value=0.017). Dyslipidemia was a risk factor for uncontrolled asthma (adjusted odds ratio [ORadj]=1.808; 95% CI, 1.167-2.801) after adjustment for age, sex, body mass index (BMI), inhaled corticosteroids (ICS) dose, smoking, hypertension, and fasting blood glucose.
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These findings highlight the importance of considering dyslipidemia as an “extrapulmonary trait” in asthma management.
Participants in the DLG had a worse forced expiratory volume in 1 second (FEV1) percent predicted (DLG vs NLG: 70.12 [21.52]% vs 76.73 [19.04]%), maximal mid-expiratory flow percent predicted (DLG vs NLG: 41.97 [24.37]% vs 50.25 [24.74]%), and FEV1/forced vital capacity ratio (DLG vs NLG: 63.02 [12.82]% vs 69.04 [13.04]%) vs NLG participants (all P <.05 and all q value <0.05). The differences were still statistically significant (all P <.05 and all q value <0.05) after adjustment.
Dyslipidemia was associated with an increased risk of older adult asthma (ORadj = 2.257; 95% CI, 1.200-4.243), nonallergic asthma (ORadj = 1.781; 95% CI=1.166, 2.720), asthma with fixed airflow limitation (ORadj = 2.259; 95% CI, 1.502-3.396), and severe asthma (ORadj = 2.055; 95% CI, 1.102-3.832) after adjustment.
The 12-month follow-up for adverse events (AE) data was completed by 447 participants. Of this group, 41 patients had severe AEs (n=447; 9.17%). More severe AEs occurred in the DLG group (NLG vs DLG: 6.6% [n=241] vs 12.1% [n=206]; P =.045). The DLG group had an increased frequency of severe AEs compared with the NLG group (DLG vs NLG: 0.20 [0.69] vs 0.12 [0.67], respectively; P =.022, q value=.034).
In the 12-month follow-up, dyslipidemia was associated with an increased frequency of severe AEs (adjusted rate ratio [RRadj]=1.910; 95% CI, 1.075-3.395) and moderate-to-severe AEs (RRadj = 1.435; 95% CI, 1.019-2.019), according to multivariable negative binomial regression models after adjustment.
Sensitivity analyses showed that findings regarding the association of dyslipidemia with airway obstruction, asthma phenotypes, and asthma exacerbations did not differ importantly from the main results, after excluding participants who were receiving statins.
Among several limitations, blood lipids were tested only once, and the effects of ICS on blood lipids cannot be ruled out. In addition, more than 80% of the participants had adult-onset asthma.
“These findings highlight the importance of considering dyslipidemia as an ‘extrapulmonary trait’ in asthma management,” stated the study authors.
