Study characteristics
| Study, year | Included in meta-analysis | Country of study | ILD sample size | Type of ILD | Age, years | Male, % | Baseline FVC, % predicted | Baseline DLCO, % predicted | Monocyte parameters | Timing of monocyte measurement | Relevant outcomes reported |
| Achaiah et al. [18], 2021 | Yes | UK | 32 | Indeterminate UIP | 76.7±6.2 | 66 | 92.6±26.9 | 64.2 (16) | >0.9×109 cells·L−1 | Within 3 months of initial CT | Visual increase in extent of disease or progression of CT to “definite” or “probable” UIP |
| Achaiah et al. [19], 2022 | Yes | UK | 1259 (mortality) 362 (progression) | Early fibrotic ILA | 63.4±8.1 | 57.2 | NA | NA | >1×109 cells·L−1 | Closest to CT; median time interval between CT and blood sample 13–30 days | Radiologic progression, all-cause mortality |
| Achaiah et al. [17], 2022 (NLR) | Yes | UK | 128 | IPF | 74.8±6.9 | 79 | 85.5 (69.9–98.0) | 6.19 (50.9–71.0) | >0.9×109 cells·L−1 | Within 4 months of presentation to ILD clinic | FVC decline >10% per year, all-cause mortality |
| Karampitsakos et al. [13], 2021 | Yes | Multinational | 300 (discovery) 189 (validation) 489 (pooled) | IPF | NA | NA | NA | NA | ≥0.95×109 cells·L−1 (pooled) ≥0.6×109 cells·L−1 (discovery and validation) | Baseline (prior to antifibrotic treatment) | All-cause mortality, 1-year disease progression as assessed by functional decline |
| Kreuter et al. [2], 2021 | Yes | USA (multicentre) | 2067 | IPF | NA | NA | NA | NA | 0.6–0.8×109 cells·L−1 ≥0.95×109 cells·L−1 | Baseline | All-cause mortality over 1 year |
| Scott et al. [4], 2019 | Yes | USA (multicentre) | 130 (Stanford) 36 (COMET) | IPF | NA | NA | NA | NA | ≥0.95×109 cells·L−1 | Stanford: within 30 days of diagnosis; COMET: baseline | Transplant-free survival (discovery), mortality (validation) |
| Teoh et al. [15], 2020 | Yes | Australia (multicentre) | 231 | IPF | 69.9±8.3 | 71 | 80.3±22 | 48.2±16.8 | ≥0.95×109 cells·L−1 | Baseline | Survival |
| Zhang et al. [14], 2022 | Yes | China (multicentre) | 34 | IPF | 64.5±9.46 | 82.69 | 77.39±20.31 | 40.36±18.71 | >0.67×109 cells·L−1 | After admission to hospital | Survival |
| Barratt et al. [9], 2021 | No | UK | 281 | fHP | 70 (65–80) | 41 | 79 (65–94) | 50 (43–64) | ≥0.95×109 cells·L−1 | At the point of diagnosis | Survival |
| Bernardinello et al. [16], 2022 | No | Italy | 77 | Newly diagnosed IPF | 70 (53–81) | 83 | 80 (50–125) | 57 (30–106) | Continuous | At diagnosis and within at least 1 year following antifibrotic therapy | FVC decline ≥5% predicted over 1 year |
| Kim et al. [11], 2021 | No | Multinational | 1659 | ILA | 78±6 | 55 | NA | NA | 1sd increment | At first clinic visit | ILA progression |
| Lv et al. [20], 2022 | No | China | 351 (pooled) | Anti-MDA5 positive DM-ILD | 53.11±11 | 33.6 | NA | NA | >0.24×109 cells·L−1 | Weekly for first 4 weeks of hospital admission | 6-month all-cause mortality |
| Shao et al. [21], 2022 | No | Austria | 95 (derivation) | Fibrotic ILD | 70.9±1.5 | 66.6 | 81±3.1 | 54.8±2.7 | ≥0.65×109 cells·L−1 | Baseline | Relative FVC decline ≥10% or DLCO decline ≥15% at 1 year, death or lung transplant |
CT: computed tomography; DLCO: diffusing capacity of the lung for carbon monoxide; DM: dermatomyositis; fHP: fibrotic hypersensitivity pneumonitis; FVC: forced vital capacity; ILA: interstitial lung abnormalities; ILD: interstitial lung disease; IPF: idiopathic pulmonary fibrosis; MDA5: melanoma differentiation-associated gene 5; NA: not applicable/available; UIP: usual interstitial pneumonia.