Which clinical features are linked with severe presentation in people tested for anti-GBM (glomerular basement membrane) antibodies?
| ISRCTN | ISRCTN80111907 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN80111907 |
| Sponsor | Medical Science Research Project of Hebei Province (Project No. 20251434) |
| Funder | Baoding No.1 Central Hospital |
- Submission date
- 28/09/2026
- Registration date
- 28/09/2026
- Last edited
- 28/09/2026
- Recruitment status
- No longer recruiting
- Overall study status
- Completed
- Condition category
- Urological and Genital Diseases
Plain English summary of protocol
Background and study aims
Anti-glomerular basement membrane (anti-GBM) antibodies can be associated with a rare autoimmune condition that may damage the kidneys and sometimes the lungs. Some people have severe kidney failure, need dialysis, or develop bleeding into the lungs when they first come to hospital, while others have a less severe presentation. Doctors use blood tests, kidney-function tests, scans, and sometimes kidney biopsy findings to understand how severe the illness is.
This study used existing hospital records to describe adults who were tested for anti-GBM antibodies and to examine a structured classification called Clinical Risk Integration (CRI). Among patients with a positive anti-GBM result, CRI classifies presentation as high risk when at least one major severity feature is present: very low kidney filtration (eGFR below 15 mL/min/1.73 m²), dialysis dependence, pulmonary hemorrhage, or simultaneous anti-GBM and ANCA antibody positivity. The study also describes kidney, lung, antibody, and biopsy findings and explores how other severity markers differ between the CRI groups.
Who can participate?
This was a retrospective study of existing medical records, so patients were not newly approached or asked to attend study visits. Eligible records were from adults aged 18 years or older who had an anti-GBM antibody test as part of routine clinical care between 1 January 2021 and 31 December 2025 and had enough information to assess kidney function and renal or pulmonary involvement. Repeat encounters and records missing the core information needed for CRI classification were excluded.
What does the study involve?
Researchers linked the first eligible record for each patient across the hospital anti-GBM laboratory registry and relevant nephrology, blood-test, urine-test, imaging, dialysis, and renal pathology records. No new treatment, blood sample, scan, biopsy, appointment, questionnaire, or other procedure was required for this research. Records were de-identified for analysis.
The study first describes patients according to whether the anti-GBM antibody result was positive or negative. Within the anti-GBM-positive group, the CRI rule is used once at the index presentation to classify high-risk or lower-risk presentation. Kidney, pulmonary, serologic, and biopsy features are then summarized and compared. Because the variables used to define CRI high risk are part of the classification itself, they are not treated as independent predictors of CRI risk class.
What are the possible benefits and risks of participating?
There is no direct clinical benefit to an individual whose historical record is included, because the research does not change their care. The study may help researchers describe the different ways anti-GBM disease presents and may guide future prospective research on early risk assessment.
The main research risk is loss of confidentiality. The study minimizes this risk by using de-identified data, restricting access to authorized research personnel, and reporting results only in aggregate so that individuals are not identified. There are no additional medical or procedural risks because no new intervention or study procedure is performed.
Where is the study run from?
The study is run from the Medical Laboratory Department of Baoding No.1 Central Hospital (China).
When is the study starting and how long is it expected to run for?
The historical clinical records cover 1 January 2021 to 31 December 2025. Retrospective record collection began on 1 February 2026, the final eligible record set was completed on 30 April 2026, and the study analysis was completed on 31 August 2026.
Who is funding the study?
Medical Science Research Project of Hebei Province (Project No. 20251434) (China).
Who is the main contact?
Wenjie Song
18132745298@163.com
Contact information
Public, Principal investigator, Scientific
Medical Laboratory Department, Baoding No.1 Central Hospital, No. 320 Changcheng North Street, Lianchi District
Baoding
071000
China
| Phone | +86 312 5976789 |
|---|---|
| 18132745298@163.com |
Scientific
Department of Ultrasound, Fourth Medical Center of PLA General Hospital, No. 51 Fucheng Road, Haidian District
Beijing
100048
China
| Phone | +86 10 66867399 |
|---|---|
| dasong.wangchao@163.com |
Scientific
Medical Laboratory Department, Baoding No.1 Central Hospital, No. 320 Changcheng North Street, Lianchi District
Baoding
071000
China
| Phone | +86 312 5976789 |
|---|---|
| sdf0323@126.com |
Scientific
Medical Laboratory Department, Baoding No.1 Central Hospital, No. 320 Changcheng North Street, Lianchi District
Baoding
071000
China
| Phone | 86 312 5976789 |
|---|---|
| 1311207076@qq.com |
Scientific
Medical Laboratory Department, Baoding No.1 Central Hospital, No. 320 Changcheng North Street, Lianchi District
Baoding
071000
China
| Phone | +86 312 5976789 |
|---|---|
| songwenjie1201@sina.com |
Study information
| Primary study design | Observational |
|---|---|
| Observational study design | Cross sectional study |
| Participant information sheet | 50360 Version 1.0 - 28 September 2026_Participant_Information_Sheet.pdf |
| Scientific title | Clinical characteristics and CRI-defined high-risk presentation among adults evaluated for anti-glomerular basement membrane antibodies: a retrospective cross-sectional analytical study at Baoding No.1 Central Hospital |
| Study acronym | CRI-GBM |
| Study objectives | The study aims to characterize the demographic, clinical, laboratory, serologic, imaging and histopathologic features of adults evaluated for anti-glomerular basement membrane (anti-GBM) antibodies at index presentation; compare anti-GBM-positive with anti-GBM-negative patients; classify anti-GBM-positive patients according to Clinical Risk Integration (CRI) as high-risk or lower-risk presentation; and identify clinical, laboratory, serologic and histopathologic features associated with CRI-defined high-risk presentation. Prespecified subgroup analyses assess differences according to symptom status, anti-GBM/ANCA overlap serology and anti-GBM antibody titer category. |
| Ethics approval(s) |
Approved 15/01/2026, Medical Ethics Committee of Baoding First Central Hospital (No. 320 Changcheng North Street, Lianchi District, Baoding, 071000, China; +86 312 5976679; bdyzxirb@163.com), ref: IRB-A27N5-2026 |
| Health condition(s) or problem(s) studied | Anti-glomerular basement membrane antibody positivity and anti-GBM disease / pulmonary-renal presentation |
| Methodology | This is a retrospective cross-sectional analytical study using existing routinely collected clinical records from Baoding No.1 Central Hospital, China. Adult patients who underwent anti-GBM antibody testing during the study period were identified consecutively from the immunology laboratory registry. The first eligible index record for each patient was linked with nephrology, clinical chemistry, hematology, urinalysis, chest imaging, dialysis and renal pathology records. Records were eligible when patients were aged 18 years or older, had a verifiable anti-GBM antibody result, sufficient renal-function information to calculate estimated glomerular filtration rate, and adequate documentation of renal and pulmonary involvement. Duplicate encounters and records without sufficient information for classification were excluded. A total of 138 records were retrieved and 91 unique eligible records were included in the final analysis, comprising 64 anti-GBM-positive and 27 anti-GBM-negative patients. Within the anti-GBM-positive cohort, CRI was used to classify presentation as high risk or lower risk at the index assessment. High-risk presentation was defined by the presence of at least one major severity feature: estimated glomerular filtration rate below 15 mL/min/1.73 m², dialysis dependence at presentation, clinically documented pulmonary hemorrhage, or concurrent anti-GBM and ANCA positivity. Anti-GBM-positive patients without these features were classified as lower risk. The primary outcome is CRI risk class at index presentation. Secondary outcomes include renal status, pulmonary status, serologic profile and renal histopathologic features, all measured from the index clinical record. Data are summarized using means and standard deviations, medians and interquartile ranges, or frequencies and percentages as appropriate. Anti-GBM-positive and anti-GBM-negative patients are compared using independent-samples t tests, Mann-Whitney U tests, chi-square tests or Fisher's exact tests according to variable type. Within the anti-GBM-positive cohort, CRI high-risk and lower-risk groups are compared using corresponding parametric or non-parametric methods. Exploratory binary logistic regression evaluates non-defining clinical, laboratory, serologic and histopathologic factors associated with high-risk presentation. Prespecified subgroup analyses examine symptom status, single-positive versus double-positive serology and anti-GBM titer category. Statistical analyses are performed using IBM SPSS Statistics, with two-sided significance set at p < 0.05. |
| Intervention type | Other |
| Primary outcome measure(s) |
|
| Key secondary outcome measure(s) |
|
| Completion date | 31/08/2026 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Mixed |
| Lower age limit | 18 Years |
| Upper age limit | 100 Years |
| Sex | All |
| Target sample size at registration | 130 |
| Total final enrolment | 91 |
| Key inclusion criteria | 1. Age 18 years or older at index evaluation 2. Documented anti-GBM antibody test performed during routine clinical care within the historical source-record period 3. Serum creatinine available at index presentation to permit eGFR calculation using the 2021 CKD-EPI creatinine equation 4. Sufficient clinical documentation to determine renal and pulmonary involvement at index presentation |
| Key exclusion criteria | 1. Age younger than 18 years 2. Repeat encounter after the first eligible index presentation 3. Record lacking core CRI classification variables: antibody status, renal-function data, or organ-involvement documentation 4. Irretrievable or unverifiable serologic or clinical source documentation |
| Date of first enrolment | 01/01/2026 |
| Date of final enrolment | 30/04/2026 |
Locations
Countries of recruitment
- China
Study participating centre
Baoding
071000
China
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Other files | Consent form version 1.0 |
28/09/2026 | 28/09/2026 | No | No |
| Participant information sheet | version 1.0 | 28/09/2026 | 28/09/2026 | No | Yes |
| Protocol file | version 1.0 | 28/09/2026 | 28/09/2026 | No | No |
| Statistical Analysis Plan | version 1.0 | 28/09/2026 | 28/09/2026 | No | No |
Additional files
- 50360 Version 1.0 - 28 September 2026_Statistical_Analysis_Plan.pdf
- Statistical Analysis Plan
- 50360 Version 1.0 - 28 September 2026_Participant_Information_Sheet.pdf
- Participant information sheet
- 50360_Informed_Consent_Waiver_Statement v1.0 28Sep2026.pdf
- Consent form
- 50360 Version 1.0 - 28 September 2026_Study_Protocol.pdf
- Protocol file
Editorial Notes
28/09/2026: Trial's existence confirmed by Medical Ethics Committee of Baoding First Central Hospital.
