Effect of anti-retroviral regimen on proximal tubular function in Zambian adolescents and young adults living with HIV

We conducted a cross-sectional study involving 180 adolescents and young adults receiving antiretroviral theray for at least 12 months at the University Teaching Hospitals (UTHs) in Lusaka, Zambia. These were either on Tenofovir or Abacavir-based antiretroviral regimen . SmartCare, a national HIV electronic medical database, was used to select eligible participants between May 2018 and March 2019 using a checklist to verify eligibility. All participants were aged between 10 and 24 years who had received ART for a minimum of 12 months and had a documented normal estimated glomerular filtration rate (eGFR) at initiation of the current antiretroviral regimen. Written informed consent and/or assent for participation in this study were obtained from each participant and/or parent or guardian. The study adhered to the declaration of Helsinki <strong>Data collection</strong> Individual participant data were collected from Smart Care, interviews, and physical examination including current age, sex, current weight, body mass index (BMI), current ART regimen and duration, baseline CD4+ cell count, self-reported 85% ART adherence, previous or current tuberculosis, and baseline creatinine or estimated Glomerular Filtration Rate (eGFR). Participants were requested to provide two first-morning spot urine specimens for urinary protein and creatinine levels to calculate a mean (2-sample) urine protein to creatinine ratio (UPCR). The second first-morning urine was obtained within 7-14 days of the first specimen. Each spot urine sample was analyzed for markers of tubular function, urinary b2-microglobulin, a1-microglobulin, creatinine, and urine phosphate. Urine β2-microglobulin and α1-microglobulin were determined by Enzyme-linked immunosorbent assays (ELISA) with detection range of 31.25—2000 ng/mL and 4.69-300 ng/mL. All reagents, samples and standards were prepared according to the instructions in the manufacturer’s manual (Wuhan Elabscience Biotechnology Co. Ltd, Donghu Hi-Tech Development Area, Wuhan, Hubei, China). The urinary proteins were expressed as the ratio-to-creatinine (a1-MCR, b2-MCR, and UPCR) to adjust for variations in urine concentration. Serum or plasma samples were analyzed for CD4+ cell count, HIV viral load, hemoglobin, calcium, potassium, uric acid, urea, phosphate, serum creatinine, and albumin.

本研究为一项横断面研究（cross-sectional study），共纳入赞比亚卢萨卡大学教学医院（University Teaching Hospitals, UTHs）中接受抗反转录病毒治疗（antiretroviral therapy, ART）至少12个月的180名青少年与青年成年人。受试者均采用基于替诺福韦（Tenofovir）或阿巴卡韦（Abacavir）的抗反转录病毒治疗方案。

本研究依托国家HIV电子医疗数据库SmartCare，于2018年5月至2019年3月期间，通过核查清单筛选符合入组标准的受试者。所有入组受试者年龄介于10～24岁之间，接受抗反转录病毒治疗时长≥12个月，且在当前抗反转录病毒治疗方案启动时，经记录确认估算肾小球滤过率（estimated glomerular filtration rate, eGFR）正常。本研究已获得每名受试者及其父母/监护人的书面知情同意，未成年受试者同步获取了未成年同意书，且严格遵循《赫尔辛基宣言》的伦理规范。

**数据采集**
本研究从SmartCare数据库、受试者访谈及体格检查中收集个体受试者数据，采集指标包括当前年龄、性别、当前体重、体质量指数（body mass index, BMI）、当前抗反转录病毒治疗方案与治疗时长、基线CD4+细胞计数、自我报告的抗反转录病毒治疗依从率达85%、既往或现患结核病，以及基线肌酐或估算肾小球滤过率（eGFR）。

受试者需提供两份首次晨尿随机尿标本，用于检测尿蛋白与肌酐水平，以计算双样本平均尿蛋白肌酐比（urine protein to creatinine ratio, UPCR）；第二份晨尿随机尿标本需于第一份标本采集后的7～14天内完成采集。每份晨尿随机尿标本均需检测肾小管功能标志物、尿β2-微球蛋白、尿α1-微球蛋白、肌酐及尿磷酸盐。

尿β2-微球蛋白与尿α1-微球蛋白采用酶联免疫吸附试验（Enzyme-linked immunosorbent assays, ELISA）进行检测，二者的检测范围分别为31.25～2000 ng/mL与4.69～300 ng/mL。所有试剂、标本及标准品均严格按照生产商手册的操作说明进行制备（武汉伊莱瑞特生物科技股份有限公司，中国湖北省武汉市东湖高新技术开发区）。

为校正尿液浓度差异，尿蛋白指标均以肌酐比值（α1-MCR、β2-MCR及UPCR）的形式表示。

本研究同时对血清或血浆标本开展多项检测，包括CD4+细胞计数、HIV病毒载量、血红蛋白、钙、钾、尿酸、尿素、磷酸盐、血清肌酐及白蛋白。