The SCTC-DI is a research instrument for organ damage in systemic sclerosis. It is not a diagnostic test and does not replace clinical assessment. Read these limitations before relying on a score.
Damage only. The index measures permanent damage, not disease activity, and does not include patient-reported outcomes.[1]
Attribution and duration are your call. Each item must be attributable to SSc (damage caused by treatment is excluded by definition), and items marked * must have been present for at least 6 months. The calculator cannot verify either.[1]
Some scoring rules are our interpretation. The paper's wording is unclear on how four add-ons attach to their items and on one renal item. We count add-ons only with the item they attach to and count persistent renal impairment on its own. The authors have not confirmed this reading.
Show the other 8 limitations (11 in total)
Score of 5. The paper's bands are low below 5, moderate 6 to 12, and high 13 or more. A score of exactly 5 has no category in the source, so the page shows "Not assigned."[1]
Severity bands vary by source. Other reviews give different band cut-offs. If you compare scores with another source, state which bands you used.
Scores above 33. The maximum score in the derivation cohort was 33. The paper states that scores above 33 are likely incompatible with life.[1]
Development data. Item reduction and weights came from a retrospective analysis of a prevalent Australian cohort (1,568 patients). Nine of the 58 retained items could not be analyzed, and some items were analyzed using their closest available equivalent.[1]
Morbidity was a surrogate. The paper notes there is no specific morbidity measure in SSc. Weights were partly derived against the SF-36 Physical Component Summary.[1]
Moderate discrimination. ROC area under the curve was 0.77 for mortality in the derivation cohort and 0.73 in the Canadian validation cohort. For morbidity it was 0.69 and 0.72.[1]
Not yet tested for reliability or feasibility. The authors state that inter-rater reliability, reproducibility, and feasibility in routine practice still need evaluation.[1]
Survey response. Item selection used a consensus survey with a 28% response rate (93 of 331 experts).[1]
Source: Ferdowsi N, et al. Ann Rheum Dis 2019;78(6):807-816 (reference 1). Interpretations made by AutoimmuneCalc carry no reference number.
How to use it. Check each item that is present and attributable to SSc. Damage means permanent, irreversible loss of structure or function, not disease activity. Items marked * must have been present for at least 6 months.
Add-on items sit under the item they attach to and unlock when that item is checked. The score updates as you go.
Musculoskeletal and skin0 of 50 ptsVascular0 of 20 ptsGastrointestinal0 of 60 ptsRespiratory0 of 30 ptsCardiovascular0 of 40 ptsRenal0 of 30 pts
About the SCTC-DI
The SCTC-DI was developed by a working group of the Scleroderma Clinical Trials Consortium as the first damage index for systemic sclerosis. The group defined damage by consensus, assembled candidate items from a systematic literature review and from patient partners and non-rheumatologist experts, and then narrowed the list with a web survey of consortium members. Of 331 experts invited, 93 gave complete responses (28.1%), and 58 of 83 candidate items were retained.
Weights were then derived from a prevalent Australian cohort. Twenty-two items were significantly related to death and/or morbidity on univariable analysis, and one more was added by the experts because of its clinical importance, giving 23 weighted items. The index predicted morbidity and mortality in an external Canadian cohort.
The index is a checklist of damage that has already happened. It is not designed to track activity, and the authors note that reliability and feasibility in routine practice still need study.
How the score is calculated
Add the weight of every item that is checked. Four add-on items (digital amputation, FVC below 70%, right ventricular dysfunction, and renal replacement therapy) count only when the item they attach to is also checked. The maximum possible total is 55.
Domain
Items
Highest possible points
Musculoskeletal and skin
5
14
Vascular
2
3
Gastrointestinal
6
10
Respiratory
3
11
Cardiovascular
4
11
Renal
3
6
Total
23
55
Source: Table 2 and the accompanying text of Ferdowsi et al. 2019[1]. The six domain groupings follow the layout of that table.
Interpreting the score
The source paper describes three damage bands. A score of exactly 5 is not covered by any band in the paper.
SCTC-DI score
Band in the source
Note
0 to 4
Low damage
Below 5 in the paper.
5
Not assigned
Falls between the paper's low and moderate bands. The calculator reports the gap.
6 to 12
Moderate damage
Moderate band in the paper.
13 or more
High damage
High band in the paper. The highest observed score in the derivation cohort was 33.
Band cut-offs vary between published sources. State which bands you used when you report or compare scores. Performance reported in the paper was moderate: area under the ROC curve 0.77 (derivation) and 0.73 (validation) for mortality, and 0.69 and 0.72 for morbidity[1].
Common pitfalls
Scoring activity as damage. The index counts damage that has already occurred. Check an item only when it meets that item's own definition and is attributable to SSc rather than to treatment or another condition.
Skipping the 6-month rule. The calculator cannot see duration. Confirm that every starred item has been present for at least 6 months before you check it.
Comparing against different bands. Another reviewer's low, moderate, and high may use different cut-offs. Compare the number and name the bands.
Frequently asked questions
What is the SCTC-DI?
The Scleroderma Clinical Trials Consortium Damage Index is a 23-item weighted checklist of permanent organ damage in systemic sclerosis (SSc). Ferdowsi and colleagues built it from expert consensus and cohort data and described it in Annals of the Rheumatic Diseases in 2019. It was the first damage index developed for SSc.
How is the SCTC-DI scored?
Each item that is present and attributable to SSc adds its weight. Four add-on items count only alongside the item they attach to. The weights add up to a maximum of 55.
What does a high SCTC-DI score mean?
In the source paper, 13 or more is the high damage band, 6 to 12 is moderate, and below 5 is low. Higher scores reflect more accumulated permanent damage, and the index predicted morbidity and mortality in the external validation cohort. It is a research instrument and does not replace clinical assessment.
Why does a score of 5 show "Not assigned"?
The paper defines low damage as below 5 and moderate damage as 6 to 12, so a score of exactly 5 falls in no band. The calculator reports that gap instead of guessing. Other reviews use different cut-offs, so say which bands you used when you report a score.
What is the highest possible SCTC-DI score?
The weights add up to 55. In the derivation cohort the highest observed score was 33, and the paper states that scores above 33 are likely incompatible with life.
Does the SCTC-DI measure disease activity?
No. It records permanent damage, meaning irreversible loss of structure or function. It does not measure disease activity or patient-reported outcomes, so pair it with an activity assessment when you need both.
How was this calculator checked?
Items, weights, and bands were taken from Table 2 and the text of the source article, then tested against hand-calculated cases for every rule, boundary, and add-on. Every place where we had to interpret the paper is listed under limitations. The page was reviewed by Mahiar Rabie, MS, MD.
References
1Ferdowsi N, Huq M, Stevens W, Hudson M, Wang M, Tay T, Burchell JL, et al.Development and validation of the Scleroderma Clinical Trials Consortium Damage Index (SCTC-DI): a novel instrument to quantify organ damage in systemic sclerosis. Ann Rheum Dis. 2019;78(6):807-816. doi:10.1136/annrheumdis-2018-214764. Source of the 23 items, weights, and severity bands used here.
2Correction notice.Correction: Development and validation of the Scleroderma Clinical Trials Consortium Damage Index (SCTC-DI). Ann Rheum Dis. 2019;78(8):e88. Reports that Figures 3 and 4 were transposed in the article; the in-text citations and legends are correct. ard.bmj.com/content/78/8/e88.
Source and credit. The SCTC-DI, its items, and its weights were created by Ferdowsi and colleagues for the Scleroderma Clinical Trials Consortium. Credit for the instrument belongs to the original authors. This page is an independent educational implementation and is not endorsed by the authors, the Scleroderma Clinical Trials Consortium, or BMJ Publishing Group.
For clinical decision support only. The SCTC-DI is a research instrument and this calculator does not replace clinical judgment or specialist evaluation. See the medical disclaimer and editorial policy.
Page history. October 7, 2026: redesigned layout, added source citation, reviewer attribution, scoring explanation, FAQ, and references. Scoring logic unchanged.
SCTC-DI score
0
of 55
Low damage
0 to 456 to 1213+
No items checked yet.
Points by domain
Musculoskeletal and skin0
Vascular0
Gastrointestinal0
Respiratory0
Cardiovascular0
Renal0
Reviewed by Mahiar Rabie, MS, MD · AutoimmuneCalc · Last reviewed October 7, 2026