Association between vitamin D serum levels and clinical, laboratory, and parasitological parameters in patients with malaria from an endemic area of the Amazon

ABSTRACT Background: Some studies have suggested the importance of vitamin D [25(OH)D] in malaria clinical practice. The prevalence of 25(OH)D deficiency in the Amazon population is not well known, and there are few studies in patients with malaria. This study aimed to evaluate 25(OH)D serum levels in patients with malaria and determine their relationships with epidemiological, clinical, laboratory, and parasitemia data. Methods: An analytical cross-sectional study of 123 patients with malaria and 122 individuals without malaria was performed in Itaituba, Pará, Brazil, from January 2018 to October 2019, by evaluating sociodemographic, clinical-epidemiological, parasitological, and laboratory data and adopting a 5% significance level. Parametric tests (Student's t-test), non-parametric tests (Mann-Whitney U), and Spearman’s correlation ([rs], for non-parametric variables) were used according to the nature of the distribution of the variables. For the qualitative variables, Pearson's chi-square test, Fisher's exact test, and the G test were used. Spearman's correlation was used to compare the results of the 25(OH)D levels and blood counts performed among patients and the control group. Results: Malaria patients residing in a mining area had 25(OH)D serum levels that were significantly lower than those in the control group residing in the mining area, though both were within normal levels. Red blood cell counts had an inverse correlation with parasitemia (Plasmodium falciparum), and platelet levels had an inverse correlation with parasitemia (Plasmodium vivax). 25(OH)D deficiency was evidenced in Itaituba, in the state of Pará, which is an endemic area of malaria in the Amazon region.

摘要

研究背景：已有研究证实维生素D[25(羟维生素D，25(OH)D)]在疟疾临床实践中的重要价值。当前亚马逊流域人群中25(OH)D缺乏的患病率仍不明确，且针对疟疾患者的相关研究较为稀缺。本研究旨在检测疟疾患者的血清25(OH)D水平，并分析其与流行病学、临床、实验室及寄生虫血症相关指标的关联。

研究方法：本研究为分析性横断面研究，于2018年1月至2019年10月在巴西帕拉州伊塔伊图巴地区开展，共纳入123例疟疾患者与122名无疟疾对照个体。研究收集了研究对象的社会人口学、临床流行病学、寄生虫学及实验室检测数据，设定检验显著性水平为5%。根据变量的分布特性，分别采用参数检验（Student t检验，Student's t-test）、非参数检验（Mann-Whitney U检验，Mann-Whitney U）及Spearman相关分析（针对非参数变量，以r_s表示）；对于定性变量，则采用Pearson卡方检验、Fisher精确检验及G检验。此外，通过Spearman相关分析比较患者组与对照组的25(OH)D水平及血常规检测结果。

研究结果：居住于矿区的疟疾患者血清25(OH)D水平显著低于矿区对照组人群，但两组的检测值均处于正常参考范围内。红细胞计数与恶性疟原虫（Plasmodium falciparum）感染引发的寄生虫血症呈负相关，血小板计数则与间日疟原虫（Plasmodium vivax）感染所致的寄生虫血症呈负相关。本研究证实，地处亚马逊疟疾流行区的帕拉州伊塔伊图巴地区存在25(OH)D缺乏现象。