Lv N, Xiao L, Camargo CA Jr, Wilson SR, Buist AS, Strub P, Nadeau KC, Ma J., Ann Am Thorac Soc. 11(8):1218-24. doi: 10.1513/AnnalsATS.201405-214OC., 2014 Oct 01
Investigators
Sandra Wilson, Ph.D., Senior Scientist
Abstract
RATIONALE: Abdominal adiposity may be an important risk factor for uncontrolled
asthma in adults, controlling for general obesity. Whether the relationship, if present,
is explained by other factors (e.g., asthma onset age, sex, and/or coexisting conditions)
is unclear.
OBJECTIVES: To examine whether clinically applicable anthropometric
measures of abdominal adiposity-waist circumference and waist-to-height ratio (WHtR)-are
related to poorer asthma control in adults with uncontrolled asthma controlling for
body mass index (BMI), and whether the relationship (if present) is explained by gastroesophageal
reflux disorder (GERD), sleep quality, or obstructive sleep apnea (OSA) or differs
by age of asthma onset or sex.
METHODS: Patients aged 18 to 70 years with
uncontrolled asthma (n = 90) participated in a 6-month randomized clinical trial.
MEASUREMENTS AND MAIN RESULTS: Baseline measures included sociodemographics,
standardized anthropometrics, Asthma Control Test (ACT), GERD Symptom Assessment Scale,
Pittsburgh Sleep Quality Index, and Berlin Questionnaire for Sleep Apnea. Participants
(mean [SD] age, 52 [12] yr) were racially and ethnically diverse, 67% women, and 69%
overweight or obese, and 71% reported their age of asthma onset was 12 years or older.
Participants had uncontrolled asthma (mean [SD] ACT score, 14.9 [3.7]) and low GERD
symptoms score (0.6 [0.4]); 67% reported poor sleep quality, and 42% had a high OSA
risk.
General linear regression results showed that worse ACT scores were
significantly associated with every SD increase in waist circumference (β= -1.03;
95% confidence interval [CI], -1.96 to -0.16; P = 0.02) and waist-to-height ratio
(β= -1.16; 95% CI, -2.00 to -0.33; P = 0.008), controlling for sociodemographics.
Waist-to-height ratio remained correlated with ACT (β= -2.30; 95% CI, -4.16 to
-0.45; P = 0.02) after further adjusting for BMI. The BMI-controlled relationship
between WHtR and ACT did not differ by age of asthma onset or sex (P > 0.05 for
interactions) and persisted after additional adjustment for GERD, sleep quality, or
OSA scores. Poor sleep quality was associated with worse ACT scores (β= -0.87;
95% CI, -1.71 to -0.03; P = 0.045) controlling for waist-to-height ratio, BMI, and
sociodemographics.
CONCLUSIONS: Abdominal adiposity by waist-to-height
ratio and poor sleep quality correlated with poorer asthma control in adults with
uncontrolled asthma, after controlling for BMI and sociodemographics. These results
warrant replication in larger studies of diverse populations. Clinical trial registered
with www.clinicaltrials.gov (NCT 01725945).