Kola I, van Blydenstein S A, Kola M, Kooverjee S, Omar S
Department of Internal Medicine, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
Division of Pulmonology, Department of Internal Medicine, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand and Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa.
Afr J Thorac Crit Care Med. 2024 Oct 14;30(3):e1041. doi: 10.7196/AJTCCM.2024.v30i3.1041. eCollection 2024.
There has been a growing interest in nutritional/lifestyle factors, including vitamin D, that may affect chronic obstructive pulmonary disease (COPD). Most data are from Caucasian populations and temperate climates, with minimal African data.
The primary objective was to determine the prevalence of vitamin D deficiency (25-hydroxyvitamin D (25(OH)D) ≤20 ng/mL) and insufficiency (25(OH)D 21 - 29 ng/mL) among patients with COPD. Secondary objectives were to investigate the association between vitamin D and demographic/lifestyle factors, lung function parameters, markers of COPD severity and corticosteroid use.
A prospective, cross-sectional study of 76 patients with COPD was conducted at a tertiary hospital in Johannesburg, South Africa. Patients were interviewed regarding demographic/lifestyle factors, COPD severity markers and corticosteroid therapy. The most recent spirometry result was recorded. Blood samples were taken for measurement of calcium, alkaline phosphatase and vitamin D levels. Patients were stratified according to vitamin D status (deficiency and non-deficiency (25(OH)D >20 ng/mL, i.e. combined insufficiency and adequate levels)), and statistical analysis was performed to assess for associations.
The sample included 72% males and 63% black African patients. The prevalences of vitamin D deficiency and insufficiency were 48% (95% confidence interval (CI) 42 - 54) and 35% (95% CI 30 - 41), respectively. A Modified Medical Research Council (mMRC) dyspnoea score ≥2 was associated with a relative risk of 1.34 (95% CI 1.05 - 1.7) for vitamin D deficiency in univariate analysis. In multivariate regression analysis, only sunlight exposure (<1 hour/day) was an independent predictor of vitamin D deficiency (odds ratio 2.4; 95% CI 1.3 - 4.5).
There was a high prevalence of suboptimal vitamin D levels in this COPD sample population. A higher mMRC score was associated with an increased risk of vitamin D deficiency, while low sunlight exposure was the only independent predictor of vitamin D deficiency.
This is the first study to provide prevalence data regarding vitamin D status in COPD patients in sub-Saharan Africa. The study highlights a relationship between vitamin D status and both symptom severity and sunlight exposure. Owing to the high prevalence of suboptimal vitamin D status among COPD patients, it may be useful to screen patients for vitamin D deficiency, especially those with a more severe phenotype. There may be scope for further studies to evaluate whether vitamin D supplementation corrects the deficiency and provides any clinical outcome benefit.
包括维生素D在内的营养/生活方式因素对慢性阻塞性肺疾病（COPD）的影响日益受到关注。大多数数据来自白种人群和温带气候地区，非洲的数据极少。
主要目的是确定慢性阻塞性肺疾病患者中维生素D缺乏（25-羟维生素D（25(OH)D）≤20 ng/mL）和不足（25(OH)D 21 - 29 ng/mL）的患病率。次要目的是研究维生素D与人口统计学/生活方式因素、肺功能参数、慢性阻塞性肺疾病严重程度标志物和皮质类固醇使用之间的关联。
在南非约翰内斯堡的一家三级医院对76例慢性阻塞性肺疾病患者进行了一项前瞻性横断面研究。就人口统计学/生活方式因素、慢性阻塞性肺疾病严重程度标志物和皮质类固醇治疗对患者进行了访谈。记录了最近的肺功能测定结果。采集血样以测量钙、碱性磷酸酶和维生素D水平。根据维生素D状态（缺乏和非缺乏（25(OH)D>20 ng/mL，即不足和充足水平合并））对患者进行分层，并进行统计分析以评估关联。
样本中72%为男性，63%为非洲黑人患者。维生素D缺乏和不足的患病率分别为48%（95%置信区间（CI）42 - 54）和35%（95%CI 30 - 41）。在单因素分析中，改良医学研究委员会（mMRC）呼吸困难评分≥2与维生素D缺乏的相对风险为1.34（95%CI 1.05 - 1.7）相关。在多变量回归分析中，只有阳光暴露（<1小时/天）是维生素D缺乏的独立预测因素（比值比2.4；95%CI 1.3 - 4.5）。
在这个慢性阻塞性肺疾病样本人群中，维生素D水平次优的患病率很高。较高的mMRC评分与维生素D缺乏风险增加相关，而阳光暴露少是维生素D缺乏的唯一独立预测因素。
这是第一项提供撒哈拉以南非洲慢性阻塞性肺疾病患者维生素D状态患病率数据的研究。该研究突出了维生素D状态与症状严重程度和阳光暴露之间的关系。由于慢性阻塞性肺疾病患者中维生素D水平次优的患病率很高，对患者进行维生素D缺乏筛查可能有用，尤其是那些具有更严重表型的患者。可能有进一步研究的空间来评估补充维生素D是否能纠正缺乏并带来任何临床结局益处。
