Okabayashi Yusuke, Tsuboi Nobuo, Amano Hoichi, Miyazaki Yoichi, Kawamura Tetsuya, Ogura Makoto, Narita Ichiei, Ninomiya Toshiharu, Yokoyama Hitoshi, Yokoo Takashi
Division of Nephrology and Hypertension, The Jikei University School of Medicine, Tokyo, Japan.
Division of Clinical Nephrology and Rheumatology, Niigata University Medical and Dental Hospital, Niigata, Japan.
BMJ Open. 2018 Oct 31;8(10):e024317. doi: 10.1136/bmjopen-2018-024317.
The clinical severity of IgA nephropathy (IgAN) at the time of biopsy diagnosis differs significantly among cases. One possible determinant of any such difference is the time taken for referral from the primary care physician to a nephrologist, but the definitive cause remains unclear. This study examined the contribution of the number of nephrologists per regional population as a potential social factor influencing the clinical severity at diagnosis among patients with IgAN in Japan, which has an ethnically homogeneous population.
A cross-sectional study.
Patients were registered in the Japan Renal Biopsy Registry (J-RBR), a nationwide multicentre registry, and 6426 patients diagnosed with IgAN were analysed. The facilities registered to the J-RBR were divided into 10 regions and the clinical features of IgAN at biopsy diagnosis, including renal function and level of proteinuria, were examined.
Renal prognosis risk at the time of biopsy diagnosis defined by Kidney Disease Improving Global Outcomes guideline 2012.
Among the regions, there were significant differences in the estimated glomerular filtration rate (67.5-91.4 mL/min/1.73 m), urinary protein excretion rate (0.93-1.93 g/day) and renal prognosis risk group distribution at diagnosis. The severity of all clinical parameters was inversely correlated with the number of nephrologists per regional population, which showed an up to 2.7-fold difference among regions. A generalised linear mixed model revealed that a low number of nephrologists per regional population were significantly associated with fulfilment of clinical criteria indicating a very-high-risk renal prognosis (β=-0.484, 95% CI -0.959 to -0.010).
Among Japanese patients with IgAN, significant regional differences were detected in clinical severity at the time of diagnosis. Social factors, such as an uneven distribution of nephrologists across regions, may influence the timing of biopsy and determine such differences.
IgA 肾病（IgAN）活检诊断时的临床严重程度在不同病例间存在显著差异。造成这种差异的一个可能决定因素是从初级保健医生转诊至肾病专家所需的时间，但确切原因仍不清楚。本研究调查了日本种族同质化人群中，每地区人口的肾病专家数量作为影响 IgAN 患者诊断时临床严重程度的潜在社会因素所起的作用。
一项横断面研究。
患者登记于日本肾活检登记处（J-RBR），这是一个全国性的多中心登记处，对 6426 例诊断为 IgAN 的患者进行了分析。登记至 J-RBR 的机构被分为 10 个地区，并对 IgAN 活检诊断时的临床特征，包括肾功能和蛋白尿水平进行了检查。
根据 2012 年改善全球肾脏病预后组织（KDIGO）指南定义的活检诊断时的肾脏预后风险。
各地区间，估计肾小球滤过率（67.5 - 91.4 mL/min/1.73 m²）、尿蛋白排泄率（0.93 - 1.93 g/天）以及诊断时的肾脏预后风险组分布存在显著差异。所有临床参数的严重程度与每地区人口的肾病专家数量呈负相关，各地区间差异高达 2.7 倍。广义线性混合模型显示，每地区人口的肾病专家数量少与符合提示极高风险肾脏预后的临床标准显著相关（β = -0.484，95%CI -0.959 至 -0.010）。
在日本 IgAN 患者中，诊断时的临床严重程度存在显著的地区差异。社会因素，如肾病专家在各地区分布不均，可能影响活检时机并导致这些差异。
