Plasma Leptin and Reduced FEV 1 and FVC in Chronic Spinal Cord Injury.

BACKGROUND: Adipose tissue produces leptin, which is pro-inflammatory, and adiponectin, which has anti-inflammatory properties. Participants with chronic spinal cord injury (SCI) have increased body fat and are at increased risk for respiratory illness.

OBJECTIVE: To assess the associations between leptin and adiponectin with pulmonary function in a chronic SCI cohort.

DESIGN: Cross-sectional study.

SETTING: Veterans Affairs Medical Center.

PARTICIPANTS: A total of 285 participants (237 men and 48 women) with chronic SCI with mean (standard deviation) injury duration 17.8 (13.2) years from the VA Boston and the community participating in an epidemiologic study assessing factors associated with respiratory health.

METHODS: Participants (24.6% cervical American Spinal Injury Association Impairment Scale (AIS) level A, B, and C; 33.6% other AIS A, B, and C; 41.8% AIS D) provided a blood sample, completed a respiratory health questionnaire, and underwent spirometry. Linear regression methods were used to assess cross-sectional associations between plasma leptin and adiponectin with spirometric measures of pulmonary function adjusted for age, race, gender, and height. Level and severity of SCI, mobility mode, body mass index, smoking, chronic obstructive pulmonary disease, asthma, chest injury history, laboratory batch, and other potential confounders were also considered.

MAIN OUTCOME MEASUREMENTS: forced expiratory volume in 1 second (FEV1 ), forced vital capacity (FVC), and FEV1 /FVC.

RESULTS: There was a statistically significant inverse relationship between plasma leptin assessed in quartiles or as a continuous covariate with FEV1 and FVC. In fully adjusted models, each interquartile range (16,214 pg/mL) increase in leptin was associated with a significant decrease in FEV1 (-93.1 mL; 95% confidence interval = -166.2, -20.0) and decrease in FVC (-130.7 mL; 95% confidence interval = -219.4, -42.0). There were no significant associations between leptin and FEV1 /FVC or between plasma adiponectin with FEV1 , FVC, or FEV1 /FVC.

CONCLUSION: Plasma leptin in individuals with chronic SCI is inversely associated with FEV1 and FVC, independently of SCI level and severity and other covariates. This finding suggests that plasma leptin may contribute to reduced pulmonary function in chronic SCI.

LEVEL OF EVIDENCE: II.