The effect of surgical and non-surgical weight loss on N-terminal pro-B-type natriuretic peptide and its relation to obstructive sleep apnea and pulmonary function.
BACKGROUND
Obesity is a major risk factor for obstructive sleep apnea, impaired pulmonary function and heart failure, but obesity is also associated with paradoxically low levels of serum N-terminal pro-B-type natriuretic peptide (NT-proBNP). In subjects with severe obesity undergoing weight loss treatment, we assessed the associations between changes in severity of obstructive sleep apnea, pulmonary function and serum NT-proBNP levels.


METHODS
One-year non-randomized controlled clinical trial. Participants, 69.6 % women, mean (SD) age 44.6 (10.8) years and body mass index (BMI) 45.1 (5.6) kg/m(2), underwent gastric bypass surgery (n = 76) or intensive lifestyle intervention (n = 63), resulting in 30 (8) % and 8 (9) % weight loss, respectively. The reference group included 30 normal weight, healthy, gender and age matched controls. Sleep recordings, arterial blood gases, pulmonary function and blood tests were assessed before and 1 year after the interventions.


RESULTS
NT-proBNP concentrations increased significantly more after surgery than after lifestyle intervention. The post intervention values in both groups were significantly higher than in a normal weight healthy reference group. In the whole study population changes (∆) in NT-proBNP correlated significantly with changes in both BMI (r = -0.213) and apnea hypopnea index (AHI, r = -0.354). ∆NT-proBNP was, independent of age, gender and ∆BMI, associated with ∆AHI (beta -0.216, p = 0.021). ∆AHI was, independent of ∆BMI, significantly associated with changes in pO2 (beta -0.204), pCO2 (beta 0.199), forced vital capacity (beta -0.168) and forced expiratory volume first second (beta -0.160).


CONCLUSIONS
Gastric bypass surgery was associated with a greater increase in NT-proBNP concentrations than non-surgical weight loss treatment. Reduced AHI was, independent of weight loss, associated with increased NT-proBNP levels and improved dynamic lung volumes and daytime blood gases. Clinical Trial Registration ClinicalTrials.gov NCT00273104, retrospectively registered Jan 5, 2006 (study start Dec 2005).
Morbid Obesity Center, Vestfold Hospital Trust, PO Box 2168, 3103, Tønsberg, Norway.|Department of Internal Medicine, Vestfold Hospital Trust, Tønsberg, Norway.
Anne-Marie
AM
Gabrielsen
Division of Medicine, Akershus University Hospital, Lørenskog, Norway.|Institute of Clinical Medicine, Center for Heart Failure Research, University of Oslo, Oslo, Norway.
Torbjørn
T
Omland
Department of Clinical Chemistry, Vestfold Hospital Trust, Tønsberg, Norway.
Mette
M
Brokner
Morbid Obesity Center, Vestfold Hospital Trust, PO Box 2168, 3103, Tønsberg, Norway.
Jan Magnus
JM
Fredheim
Institute for Clinical Pharmacology, University of Hannover, Hanover, Germany.
Jens
J
Jordan
Department of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway.|Department of Clinical Science, University of Bergen, Bergen, Norway.
Sverre
S
Lehmann
Department of Respiratory Medicine, Oslo University Hospital, Oslo, Norway.
May Brit
MB
Lund
Morbid Obesity Center, Vestfold Hospital Trust, PO Box 2168, 3103, Tønsberg, Norway. joran.hjelmeseth@siv.no.|Department of Endocrinology, Morbid Obesity and Preventive Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway. joran.hjelmeseth@siv.no.
Jøran
J
Hjelmesæth
Morbid Obesity Center, Vestfold Hospital Trust, PO Box 2168, 3103, Tønsberg, Norway.
Dag
D
Hofsø
D000328:Adult; D015992:Body Mass Index; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D008019:Life Style; D008168:Lung / Q000503:physiopathology*; D008297:Male; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D012129:Respiratory Function Tests; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000503:physiopathology*; D015431:Weight Loss
D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain
Natriuretic peptides; Obesity; Respiration; Sleep apnea