LONDON – Having an elevated level of high-density lipoprotein cholesterol (HDL-C) is associated with an increased rate of lung function decline over time, according to results from a cohort analysis of more than 30,000 adults presented at the annual congress of the European Respiratory Society.
For forced expiratory volume in 1 second (FEV1), “there was a highly statistically significant inverse association for HDL-C for both cross-sectional and longitudinal measures of lung function,” reported Elizabeth C. Oelsner, MD, Columbia University Medical Center, New York. Those in the top quartile for HDL-C, on average, had a 9-mL greater decline in FEV1, compared with patients in the lowest quartile (P less than .001). To put this in perspective, Dr. Oelsner said this decline is comparable “to a 10-year increment in pack-years of smoking.”
Dr. Elizabeth C. Oelsner
The study, which pooled six population-based cohorts in the United States, included 31,843 adults for whom there were baseline HDL-C levels and at least two longitudinally collected spirometry readings. According to Dr. Oelsner, quality control criteria were rigorously applied. For example, spirometry measures were obtained according to contemporary standards issued by the American Thoracic Society (ATS).
The average age of the study patients was 57 years, and 45% were classified as never smokers. The mean FEV1 decline over a median follow-up of 5 years was 37 mL per year (range of 22-49 mL/year across the six cohorts). Approximately 15% of individuals had airflow limitation at baseline. There were more than 300,000 total person-years of observation in the pooled data.
In a fully adjusted cross-sectional analysis, each 1 mmol/L increase (38.67 mg/dL) in HDL-C was associated with a 9-mL lower FEV1, according to Dr. Oelsner. He said the list of adjusted variables included age, gender, pack-years of smoking, weight, and height.
Results were consistent across age groups, presence or absence of smoking history, body mass index, and the presence or absence of airflow limitations at baseline, according to Dr. Oelsner.
HDL-C’s inverse correlation with lung function has been shown in other studies, such as the MESA Lung Study, another population-based analysis, according to Dr. Oelsner. In that study, a 0.4% increase in emphysema on CT lung scans was observed for every 10 mg/dL increase in HDL-C (Am J Respir Crit Care Med. 2010;181:A2878).
In this study, “being in the highest quartile for HDL at baseline was associated with an odds ratio of 1.2 for incident airflow limitation relative to being in the lowest [quartile],” Dr. Oelsner said.
The risk of a decline in airway function from an elevated HDL-C, if confirmed, should be considered in the context of the well-known protective effect exerted by HDL against cardiovascular events, according to Dr. Oelsner. However, she added, these data suggest that “having an excessively high HDL-C may incur risk just as an excessively low HDL may incur risk.” She noted, “there may be a limitation to the good of the good cholesterol.”
When asked after these data were presented whether she would prefer to have a low or high HDL-C, Dr. Oelsner responded, “Everything in moderation.” She also suggested that studies of treatments designed to raise HDL-C to reduce cardiovascular risk should take lung function into consideration. She warned that adverse effects on lung function are a potential “off-target risk” from such therapies.