Table 1

Overarching principles and points to consider for minimal reporting requirements in synovial tissue clinical practice and research in rheumatology, with levels of evidence (LoE) and levels of agreement (LoA)

Overarching principlesLoA mean (SD);
% of votes ≥8/10
1. Synovial biopsies (single and sequential), performed in aseptic conditions, are safe, well-tolerated and can be performed for both clinical and research purposes.9.77 (0.53), 100%
2. In both clinical and research settings, synovial biopsies should be guided by imaging techniques. Arthroscopy and ultrasound are the preferred techniques to guide synovial biopsies.9.71 (0.56), 100%
3. Ultrasound or arthroscopy can be used to guide the synovial biopsy without affecting the tolerability of the procedure or the minimal required tissue for meaningful analysis.9.14 (0.96), 83.6%
Points to consider

  1. The details of the biopsy procedure should be reported in every study. This should include non-exhaustively:

  • Exclusion criteria for biopsy

  • Target joint(s) and recess

  • Intra-articular steroids in the previous 4 weeks or during the procedure

  • Technique used (type and size of biopsy retrieval device)

  • Machine/probe for ultrasound guided biopsies and arthroscopic equipment

  • Adverse events

  • Operator’s experience and training (noting that no minimal training requirements are yet defined). (LoE 5)

9.38 (0.80), 100%
2. Overarching clinical study design, including aspects related to participant disease characteristics and treatments, must be defined in order to evaluate the generalisability and validity of the outcome. (LoE 5)9.81 (0.51), 100%
3. Conventional patient disease activity measures, disease stage and treatment should be described in order to evaluate the generalisability and validity of the outcome. (LoE 5)9.45 (1.19), 95%
4. Clinical and contemporary imaging characteristics of the biopsied joints should be described in order to evaluate the generalisability and validity of the outcome. (LoE 4)8.95 (1.28), 90.5%
5. Tissue handling and processing methods must be described in order to ensure reproducibility, including numbers and size of fragments allocated randomly to each analytic. (LoE 4)9.10 (1.64), 90.5%
6. Method and results of tissue quality assessment should be reported, including the percentage of graded tissue. (LoE 5)9.33 (1.06), 90.5%

  1. When histological or immunohistological analysis is performed, the scoring or analysis system should be defined including:

  • Representative images

  • Reference to original publication for validated scoring systems only

  • Digital analysis software used, including version numbers of platforms

  • Immunohistological staining protocol, including antibody sources and clones

  • Area assessed and sampling strategy

  • Numbers of observers and intra- and inter-observer variability. (LoE 5)

9.48 (0.75), 100%
8. Methods of extraction and quantification should be defined, and purity, quantity and quality of DNA/RNA should be reported (LoE 5).9.67 (0.58), 100%

  1. In case of single cell analysis, methods used and quality outcomes should be detailed, including:

  • Methods of tissue or cell preservation

  • Methods of tissue dissociation

  • Percentage of viable cells

  • Percentage of mitochondrial gene expression seen in the sequenced cells and the threshold chosen for analysis

  • If sorting is used, the strategy used and purity of sorted cells.

(LoE 4)		9.71 (0.56), 100%

  • LoA, Level of agreement; LoE, Level of Evidence; SD, Standard deviation.