Serum KL-6 and lung ultrasound B-lines: a combined non-invasive model for screening and predicting interstitial lung disease in idiopathic inflammatory myopathy
Authors' conclusion
KL-6 ≥553 U/mL and B-lines ≥25 are effective screening thresholds, with combined use significantly improving diagnostic accuracy.
Study context
- Population
- Patients diagnosed with idiopathic inflammatory myopathy (IIM) between 2020 and 2024, single centresingle-centre
- Participants
- 162 patients
- Comparison
- Serum KL-6 and lung ultrasound (LUS) B-lines, alone and combined, vs high-resolution CT (HRCT) as reference standard for interstitial lung disease (ILD) in IIM
- LUS B-linesn = 120
- Outcome
- Diagnostic performance for ILD (HRCT reference standard)
Methodological detailssingle-centre, observational, ROC curve analysis, combined nomogram
- Single-centre
- Observational
- ROC curve analysis
- Combined nomogram
Performance
As reported in the abstract
Diagnosis of ILD (HRCT reference)
| Test or model | Cut-off | AUC | Sensitivity | Specificity | Threshold |
|---|---|---|---|---|---|
| KL-6 | 553 U/mL | 0.895 | 69% | 95.9% | |
| LUS B-lines | 98.8% | 25 | |||
| Combination | 0.984 |
Cut-off
KL-6553 U/mL
LUS B-lines— not stated in the abstract
Combination— not stated in the abstract
AUC
KL-60.895
LUS B-lines— not stated in the abstract
Combination0.984
Sensitivity
KL-669%
LUS B-lines98.8%
Combination— not stated in the abstract
Specificity
KL-695.9%
LUS B-lines— not stated in the abstract
Combination— not stated in the abstract
Threshold
KL-6— not stated in the abstract
LUS B-lines25
Combination— not stated in the abstract
Further findings
Prediction of rapid-progressive ILD (exploratory subgroup analysis)
- KL-6 and B-lines showed only modest predictive value (AUC)
- ≈ 0.65
- Exploratory analysis
Original publication
Serum KL-6 and lung ultrasound B-lines: a combined non-invasive model for screening and predicting interstitial lung disease in idiopathic inflammatory myopathy. RMD Open. Published 21 May 2026. doi:10.
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