The influence of disease severity and lifestyle factors on the peak annual 25(OH)D value of COPD patients

Abstract

Background

The prevalence of individuals deficient in vitamin D (defined as a serum level of the stable metabolite 25(OH)D <50 nmol/L) is increasing in countries with low annual ultraviolet (UV) radiation and among individuals unable to perform outdoor activities, for example, COPD patients.

Objective

To assess the role of vitamin D deficiency, independently of seasonal variation, the peak annual value of 25(OH)D was measured in subjects with advanced COPD ± long-term oxygen therapy (LTOT) and lung healthy control subjects. A method to grade the individual annual UV light exposure was designed and tested.

Subjects and methods

Sixty-six Caucasians with advanced COPD (28 with LTOT) and 47 control subjects were included, and the levels of 25(OH)D were determined in late summer/early fall when the annual peak was assumed. Questionnaires about COPD symptoms, general health, lifestyle, dietary habits and QoL were used to collect data. Lung function tests and blood sampling were performed.

Results

The peak annual 25(OH)D of COPD subjects was significantly lower than in the control subjects, but there was no significant difference between COPD patients with and without LTOT. Ongoing vitamin D supplementation was the single most important intervention to maintain 25(OH)D levels ≥50 nmol/L. Among vitamin D-deficient COPD subjects, 25(OH) D correlated positively with forced expiratory volume in 1 second as % predicted, Modified British Medical Research Council score, blood oxygenation, food portion size, Mediterranean Diet Score and Ultraviolet Score.

Conclusion

Vitamin D deficiency was common among healthy individuals and COPD subjects. Peak annual 25(OH)D levels of COPD subjects correlated with clinically important outcomes. The present study emphasizes the need to routinely monitor vitamin D status among patients with advanced COPD and to consider to medicate those with vitamin D deficiency with vitamin D supplementation.

Keywords:

• chronic obstructive pulmonary disease
• inflammation
• long-term oxygen therapy
• quality of life
• vitamin D
• ultraviolet score

Acknowledgments

The authors thank all the subjects in this study for their committed participation in this research. The authors also thank M Romanovich for administration of the permission to use the St George’s Respiratory Questionnaire and Bo Rolander for statistical support. This work was supported by grants to HLP (from the County Council of Östergötland Region Östergötland, ALF), Sweden (grant numbers LIO-275901, LIO-355741, LIO-432861, LIO-534761, LIO-601911 and LIO-697521), the Medical Research Council of Southeast Sweden (FORSS; grant numbers FORSS-308331 and FORSS-559931), the Linköping University Hospital Foundation for Medical Research, Sweden (grant number LIO-475131), the Heart and Lung Foundation, Sweden (grant numbers 20140245 and 20140330) and the Swedish Society of Medicine (grant number SLS-368431); to PL from the County Council of Östergötland (ALF), Sweden (grant number LIO-201751) and the Medical Research Council of Southeast Sweden (FORSS; grant number FORSS-226801); and to MK from the County Council of Jönköping (Futurum), Sweden (grant numbers FUTURUM-342821, FUTURUM-489691, FUTURUM-608651, FUTURUM-712082 and FUTURUM-712181).

Part of the results were presented in a poster session at the European Respiratory Society (ERS) 2013 Annual Congress; September 711, Barcelona, Spain.

Author contributions

MK designed the study, performed the statistical analysis and wrote the manuscript. PL designed the study, performed analyses of 25(OH)D and omega-3 index, constructed the UVS, collected and analyzed data and wrote parts of the manuscript. PJ examined and included the study subjects, collected data and participated in manuscript writing. HLP designed the study, examined and included the study subjects, collected and analyzed data and wrote the manuscript. All authors have given their final approval of the version submitted. This study was performed at the Department of Pulmonary Medicine, Linköping University, Sweden. All authors contributed toward data analysis, drafting and revising the paper and agree to be accountable for all aspects of the work.

Disclosure

HLP has received honoraria for advisory boards/lectures from AstraZeneca, Boehringer Ingelheim, Novartis, Takeda Nycomed, Almirall, Intermune and Roche. MK has received honoraria for lectures from AstraZeneca, Boerhinger Ingelheim, Novartis, Roche, Lilly and Pfizer. None of these disclosures influenced the present study in any way. The other authors report no conflicts of interest in this work.