Associations of Vitamin D, chronic obstructive pulmonary disease and acute exacerbations of COPD with anxiety and depression: a nested case control study

Background: Lower vitamin D levels have not only been associated with chronic obstructive pulmonary disease (COPD), exacerbations and lower lung functions, but also with anxiety and depression. We examined the associations of severity of anxiety and depression using HAM-A (Hamilton Anxiety Rating Scale) and HAM-D (Hamilton Depression Rating Scale) scores with COPD and vitamin D levels. Methods: : Observational nested case control study was conducted in MUDHRA cohort. One hundred COPD subjects and 100 age- gender- matched non-COPD subjects (controls) underwent evaluation of socioeconomic status, respiratory symptoms, spirometry, severity of anxiety and depression, six minute walk test and estimation of serum vitamin D levels. Independent association of low vitamin D levels with severity of anxiety and depression was assessed by logistic regression. Results: : COPD group had higher mean±SD anxiety and depression scores (HAM-A 8.0±3.5, HAM-D 8.72±4) compared to control group (HAM-A 4.51±2.2, HAM-D 4.3±2). The COPD group had 53 subjects with mild/moderate anxiety/depression whereas control group had 16 subjects with mild/moderate anxiety/depression. In COPD group, subjects with mild/moderate anxiety/depression had lower vitamin D levels compared to subjects with no/minimal anxiety/depression, while the difference in control group was not significant. In logistic regression, anxiety and depression levels had independent association with vitamin D levels, lung function variables, six-minute walk distance and presence of COPD. In COPD subgroup, anxiety and depression levels had independent association with breathlessness, GOLD FEV1 staging, CAT score, SGRQ-C Symptom score and exacerbation of COPD. Conclusions: : Greater proportion of COPD subjects suffer from anxiety and depression as compared to subjects without COPD. Severity of anxiety and depression was greater in COPD subjects. Poorer lung functions, higher respiratory symptoms and lower vitamin D levels are associated with higher levels of anxiety and depression in COPD subjects.  There is an urgent need to recognise anxiety and depression in COPD patients.