生物与医学2020medrxiv.org
维生素 D 不足在重症 COVID-19 中普遍存在
Vitamin D Insufficiency is Prevalent in Severe Covid-19
入门 · 约 30 分钟读完前置知识：基础统计学、相关性分析与因果推断的区别
导读
这篇预印本研究维生素D不足与新冠重症之间的关系，发现重症新冠患者中维生素D不足的比例很高。评论普遍指出这是回顾性研究、样本很小，只能说明相关性，需要干预性对照试验来验证因果关系。
HN 关注点：疫情期间大家关心维生素D能否影响新冠严重程度，讨论焦点是这项研究是否可信、相关性能否推出因果。
HN 评论精选
这几条评论里：质疑 2 补充 1 亲历 1
补充研究虽弱但值得跟进，已有更强数据支持维生素D与轻症相关，建议适量补充并等待对照试验
这项研究很弱，因为是回顾性的：只是查了现有病历，而且只找到20名记录了维生素D水平的新冠患者。但发现足够引人注目，值得要求更好的研究。其实已有一项更好的研究，直接检测了大量新冠患者的维生素D水平，发现维生素D与更轻的病情强相关：只有26%的患者25(OH)D正常，其中86%是轻症；约38%处于不足区间，仅1.3%为轻症；约36%缺乏，病情分布明显偏向重症和危重，仅1.4%轻症、40%重症、33%危重。下一步应该做真正补充维生素D的对照试验来提供因果证据。不过避免维生素D缺乏本身已被充分研究、益处很多，值得每个人去做。但也不宜过量补充，每天1700 IU左右或晒太阳即可。
gregwebs查看英文原文
This is a very weak study because it is retrospective: they just looked at existing medical records. And they only found 20 COVID patients that had vitamin D levels recorded. But the finding is compelling enough that we should demand better studies. Actually there already is a better study where they actually tested vitamin D levels of many COVID patients [1]. It found vitamin D was strongly associated with less severe outcomes: > Only 26% of the cases had 25(OH)D in the normal range, and virtually all of them (86%) had a mild outcome. ... Just over a third (38%) had 25(OH)D in the insufficient range, and only one of them (1.3%) had a mild outcome. ... Just over a third (36%) had 25(OH)D in the deficient range, and their distribution was pushed further toward severe and critical outcomes. Only one patient (1.4%) had a mild outcome, while 26% had an ordinary outcome, 40% had a severe outcome, and 33% had a critical outcome. Now we should demand a controlled trial where they actually give a vitamin D intervention: this would provide causal evidence. However, avoiding vitamin D deficiency is already very well studied and has so many benefits that I think it is worth everyone's time and effort to do so. Many people are advising high levels of vitamin D supplementation. However, there is reason to not overdo it on vitamin D supplementation and take just 1700 IU/day (or to just get sunshine) [2]. Of course, getting your vitamin D levels tested (with the help of by a doctor) is the safe way to go about this. [1] https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3571484 [2] https://chrismasterjohnphd.com/covid-19/update-on-vitamin-d-and-covid-19-using-the-first-observational-study-released
质疑质疑因果：维生素D水平可能只是健康生活方式的代理指标
这没通过我对相关性与因果关系的直觉检验。我怀疑维生素D不足与新冠的共病因素（久坐生活方式、高血压、体重问题）高度相关；反过来，维生素D水平好的人可能生活方式更健康、共病更少。
kryogen1c查看英文原文
this doesnt pass the correlation vs causation smell test for me. i suspect VID correlates well with COVID comorbidities, like a sedentary lifestyle, hypertension, and weight problems. the opposite is also probably true, that people with good vit D levels correlate with healthier lifestyles and fewer comorbidities.
质疑指出论文引用的波士顿研究数据有误，有症状者被排除后才出现100%无症状
作者似乎误解了他们引用的波士顿研究。文中说'波士顿流浪者收容所147名新冠阳性者100%无症状'，但那项研究实际上排除了15名有症状的人——这些人在实施普遍检测前就被识别并移出了收容所。所以剩下的人100%无症状并不奇怪。
trott查看英文原文
It seems that the authors misunderstood the Boston study they are citing: > In a Boston homeless shelter, 100% of 147 COVID-19 positive subjects were asymptomatic [3]. That study actually excluded N=15 symptomatic people: > The original cases (N=15) were identified sequentially over a 5-day period, and each was expeditiously removed from the shelter population at the time of symptom recognition. These individuals predated the implementation of universal testing procedures and are excluded from this study. So, it's rather unsurprising that 100% of the remaining people were asymptomatic.
亲历亲历：检测发现严重缺乏，补充后状态改善，建议体检时顺便测维生素D
有意思的是，在HN上提到维生素时，常听到'维生素D是大多数人真正缺乏、应该补充的那一种'。我多年来断断续续补充过。疫情初期碰巧要做体检，我听说维生素D与新冠的关联，就让医生加了维生素D检测，结果确实严重缺乏。我开始每天服4000 IU，整体状态有可感知的改善——当然可能是安慰剂效应，我也不认为它必然影响我是否会得新冠。但这算又一个佐证'维生素D值得补充'的轶事。如果拿不准，可以像我一样下次体检时让医生测一下。
mindcrime查看英文原文
Interesting thing... Vitamin D is one of those things that, when vitamins come up on HN, you will often hear the refrain that "it's the one vitamin that large numbers of people are actually deficient in and ought to supplement." I've heard that many times over the years and I have taken a Vitamin D supplement on and off (more off than on) over the years. When this COVID-19 thing first hit, I had a physical scheduled (by chance) just about the same time, and I'd heard about this Vitamin D / COVID-19 connection, so when I went in for my physical, I asked my doctor to order a Vitamin D test as part of my bloodwork. As it turns out, I was indeed very deficient in Vitamin D. I started taking 4000 IU a day and it's had a noticeable impact on my overall sense of wellbeing. It could, of course, be placebo effect even so. And I have no particular reason to think that it will make any difference one way or the other in terms of me getting COVID-19. But I thought it was worth pointing out one more anecdote that suggests that the old "Vitamin D is worth supplementing" refrain might just be true. If you're in doubt, and it's an option, do what I did... just ask your doctor to run a Vitamin D test next time you go in for a checkup / physical.
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