Socioeconomic disparities of patients with acute kidney injury: subgroup analysis of local hospitals in China from a national survey : Chinese Medical Journal

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Socioeconomic disparities of patients with acute kidney injury: subgroup analysis of local hospitals in China from a national survey

Wu, Lihua1; Wang, Jinwei2; Ma, Yaqi1; Luan, Fengwu1; Wang, Mengting1; Feng, Zhihong1; Tian, Yanhong1; Li, Lu1; Chu, Rui1; Yin, Xiaolong1; Wang, Yan1; Li, Yanmei1; Guo, Xiaoyan1; Zhou, Xiaoling1; Yu, Min1; Yan, Yinyin1; Yang, Li2; Chen, Menghua1

Editor(s): Ji, Yuanyuan

Author Information
Chinese Medical Journal ():10.1097/CM9.0000000000002330, December 30, 2022. | DOI: 10.1097/CM9.0000000000002330

To the Editor: Acute kidney injury (AKI) is a common public health problem worldwide, which can adversely affect patients’ quality of life and even lead to death.[1] Academic hospitals play an important role in admitting and providing treatment for patients with AKI, but limited data exist regarding the characteristics of patients in county-level local hospitals. Our research group initiated a comprehensive survey as part of the International Society of Nephrology's “0 by 25” project (eliminating all deaths related to untreated AKI by 2025) for investigating the disease burden of AKI and its associated risk factors and prognosis through 22 province-level regions of China in 2013. We found that the detection rate of AKI in local hospitals was significantly lower than that in academic hospitals (1.66% vs. 2.20%).[2] In addition, the level of economic development of the region where a hospital was located was an independent risk factor for the under-recognition of AKI. Therefore, in this study, we aim to further describe the characteristics of the patients detected with AKI specifically in local hospitals and determine whether economic development was associated with the prognosis of AKI based on the above-mentioned nationwide survey in China.

The flowchart of the selection of patients is shown in Supplementary Figure 1, During January and July of 2013, a total of 116,788 patients had been admitted to 22 local hospitals, among whom, 1942 patients were identified as AKI using the expanded diagnostic criteria [Supplementary Materials,]. By dividing the regions where the patients were sourced into tertiles according to per capita gross domestic product (pcGDP), thus representing underdeveloped, moderately developed, and developed regions, we found that the detection rate was lowest in underdeveloped regions but highest in moderately developed regions according to both the Kidney Disease Improving Global Outcomes guideline criteria[3] (0.49%, 0.82%, and 0.67% through the tertiles of pcGDP) and the expanded criteria (1.24%, 2.04%, and 1.57% through the tertiles of pcGDP). Local hospitals in developed regions had both the lowest non-recognition rate and the highest timely recognition rate than the other two groups of regions, while no obvious differences were observed between the underdeveloped and moderately developed regions (67.0%, 73.5%, and 75.7% for non-recognition and 28.7%, 21.2%, and 18.1% for timely recognition through the three groups of regions). With respect to the severity of AKI, local hospitals from the underdeveloped regions featured the lowest proportion of stage 1 patients (37.2% vs. 48.1% and 44.8% in the other two groups) but the highest proportion of stage 3 patients (37.9% vs. 25.1% and 25.7%). When it comes to prognosis, similarly, local hospitals in underdeveloped regions had the lowest proportion of full recovery (28.2% vs. 37.4% and 36.6% in the other two groups), the highest proportion of failure in recovery (34.4% vs. 29.4% and 31.6%), and the highest proportion of in-hospital mortality (15.5% vs. 10.3% and 7.0%) [Supplementary Table 1,]. The low detection rate of AKI in local hospitals in underdevelopment regions may lie in the lower frequency of serum creatinine testing, while the higher rate of non-recognition, more advanced stage of patients, and poorer prognosis may reflect lacking competence in the diagnosis and treatment of patients. However, we found the local hospitals in moderately developed regions had comparable ability in the diagnosis and management of patients with AKI compared with those in developed regions, except that the in-hospital mortality was still much lower in the later ones.

In the analysis of the association between risk factors and in-hospital mortality, only those with complete information on the survival status (n = 1913) were used. Missing data were filled with a separate category before the corresponding variables were included in the multivariable logistic analysis. Totally, 200 deaths during hospitalization (10.5%) occurred. The risk factors with statistical significance in the univariate analysis, as well as age, a key characteristic informing prognosis, were included in the multivariable analysis. We found that older age, male sex, located in the north region, sourced from hospitals with lower pcGDP levels, using nephrotoxic drugs, with other critical illnesses, advanced AKI stages, delayed recognition of AKI, and staying in intensive care units were independently associated with the outcome (all P values < 0.05) [Table 1].

Table 1 - Analysis of risk factors affecting in-hospital mortality of AKI patients in local hospitals.
Univariate logistic regression analysis Multivariable logistic regression analysis

Factors OR (95% CI) P value OR (95% CI) P value
 18–39 years 1 (reference) 1 (reference)
 40–59 years 1.21 (0.70–2.12) 0.50 1.22 (0.64–2.32) 0.54
 60–79 years 0.83 (0.48–1.44) 0.51 0.87 (0.46–1.65) 0.68
 ≥80 years 1.56 (0.89–2.73) 0.12 2.34 (1.21–4.56) 0.01
Sex (male vs. female) 1.68 (1.20–2.34) 0.003 1.60 (1.10–2.33) 0.02
 North 1 (reference)
 South 0.42 (0.30–0.59) <0.001 0.43 (0.27–0.71) 0.001
 Northwest 0.43 (0.10–1.87) 0.26 0.88 (0.17–4.54) 0.88
 Southwest 0.52 (0.34–0.79) 0.002 0.54 (0.29–0.99) 0.05
 Tertile 1 (n = 414) 1 (reference) 1 (reference)
 Tertile 2 (n = 940) 0.63 (0.45–0.88) 0.007 0.75 (0.45–1.25) 0.27
 Tertile 3 (n = 559) 0.41 (0.27–0.63) <0.001 0.44 (0.25–0.78) 0.005
AKI classification
 Pre-renal 1.12 (0.83–1.50) 0.47
 Intrinsic-renal 1.47 (1.07–2.02) 0.02 1.06 (0.72–1.57) 0.77
 Post-renal 0.39 (0.19–0.76) 0.006 0.50 (0.23–1.07) 0.07
 Unclassified 0.56 (0.32–1.01) 0.05
Injury factors
 Renal hypoperfusion 1.67 (1.12–2.50) 0.01 1.09 (0.68–1.74) 0.74
 Nephrotoxic drugs 2.64 (1.77–3.94) <0.001 2.02 (1.28–3.20) 0.003
 Environmental toxins 1.14 (0.51–2.53) 0.76
 Sepsis 1.49 (0.93–2.41) 0.10
 Other critical illness 9.42 (6.37–13.93) <0.001 6.31 (3.93–10.15) <0.001
 Surgery 1.58 (1.06–2.37) 0.03 1.14 (0.70–1.84) 0.60
AKI stage
 Stage 1 1 (reference) 1 (reference)
 Stage 2 1.88 (1.24–2.84) 0.003 1.79 (1.13–2.83) 0.01
 Stage 3 4.24 (2.94–6.12) <0.001 3.59 (2.28–5.67) <0.001
Delayed recognition vs. timely recognition 2.59 (1.51–4.43) 0.001 2.77 (1.47–5.22) 0.002
ICU 3.13 (2.30–4.25) <0.001 1.61 (1.08–2.40) 0.02
Indication for RRT 3.16 (2.13–4.69) <0.001 1.74 (0.94–3.22) 0.08
RRT rate 2.43 (1.43–4.12) 0.001 0.81 (0.35–1.83) 0.61
Nephrology referral 1.16 (0.81–1.66) 0.41
 Diabetes 0.93 (0.63–1.38) 0.72
 Hypertension 0.86 (0.63–1.16) 0.32
 Pre-existing CKD 0.74 (0.50–1.11) 0.14
 Cardiovascular disease 1.25 (0.93–1.68) 0.14
 CLD 1.45 (0.88–2.38) 0.14
 CPD 1.13 (0.76–1.68) 0.55
 CEVD 1.54 (1.09–2.18) 0.01 1.44 (0.94–2.20) 0.10
 Anemia 1.36 (0.96–1.92) 0.08
 Other CVD 0.84 (0.57–1.24) 0.39
 Malignancy 2.72 (1.94–3.83) <0.001 1.56 (0.99–2.45) 0.05
1913 cases were included in the analysis after excluding 29 cases missing the information for all-cause in-hospital mortality. AKI: Acute kidney injury; CI: Confidence interval; CEVD: Cerebrovascular disease; CKD: Chronic kidney disease; CLD: Chronic liver disease; CPD: Chronic pulmonary disease; CVD: Cardiovascular disease; ICU: Intensive care unit; OR: Odds ratio; pcGDP: Per capita gross domestic product; RRT: Renal replacement therapy.

Our study provided a comprehensive description of the characteristics of patients with AKI admitted to local hospitals in China by using a national representative sample. Despite the advantage, some limitations should be considered. First, the identification of AKI was only based on the criteria relating to change of serum creatinine, while that of urine output, though also recommended as diagnostic criteria in the Kidney Disease Improve Global Outcomes clinical guideline, was not considered due to lack of data.[3] Second, repeated measurement of serum creatinine may be lacking and thus lead to missing the detection of AKI. However, the limitation, otherwise, could convey useful information representing clinical ability among different local hospitals. Third, as having been stated in our previously published main article, we only extracted data in 2 months of the year due to the heavy workload involved in the study and the consideration of the seasonal influence on the etiology of AKI.[2]

In conclusion, local hospitals in the underdeveloped areas of China showed some inferiority in the detection and management of patients with AKI than the more economically developed areas. The economical level as well as other clinical risk factors may contribute to the prognosis of AKI.

Declaration of patient consent

This study was performed in accordance with the Declaration of Helsinki, approved by the Ethics Committee of Peking University First Hospital, and the requirement for informed consent was waived due to the retrospective nature of the study (2014[729]).


We thank all the group members of International Society of Nephrology's “0 by 25” Project China Consortium for their contributions.


This study was supported by grants from the National Natural Science Foundation of China (Nos. 91742205, 81625004, and 81860129), the Beijing Young Scientist Program (No. BJJWZYJH01201910001006), and the Peking University Clinical Scientist Program by the Fundamental Research Funds for the Central Universities.

Conflicts of interest



1. Lewington AJ, Cerda J, Mehta RL. Raising awareness of acute kidney injury: a global perspective of a silent killer. Kidney Int 2013;84:457–467. doi: 10.1038/ki.2013.153.
2. Yang L, Xing GL, Wang L, Wu YG, Li SH, Xu G, et al. Acute kidney injury in China: a cross-sectional survey. Lancet 2015;386:1465–1471. doi: 10.1016/S0140-6736(15)00344-X.
3. Kidney Disease: Improving Global Outcomes (KDIGO) Acute Kidney Injury Work Group. KDIGO clinical practice guideline for acute kidney injury. Kidney Int Suppl 2012;2:1–138. doi: 10.1038/kisup.2012.1.

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