The IgG4-RD Responder Index is a research instrument for recording disease activity and damage organ by organ. It was developed for use in clinical trials and is not a diagnostic test. Read these limitations before relying on a score.
Urgency is a clinician judgment. The scoring rules define urgent disease in general terms only, with no site-by-site list. In validation, investigators identified urgent disease correctly 76% of the time, so the urgent doubling is the least reliable part of the score.[1][3]
No response threshold. The source defines no cut-off for response. This calculator shows the change in total between visits. It does not classify anyone as a responder.[1][3]
No maximum total. The source does not state a maximum. Each "Other" entry is counted separately and the total is not capped.[1][3]
Show the other 9 limitations (12 in total)
Damage is separate from activity. Damage is recorded but does not change the activity total. Surgery beyond fine-needle aspiration is counted as damage by design.[1]
Symptom flags do not score. Symptomatic flags and the constitutional symptoms domain are recorded and counted. They do not change the activity total.[1]
Imaging can lag the score. If a manifestation needs follow-up imaging to judge change, the paper says it should be scored 2 (unchanged). The recorded score may therefore lag the true clinical state.[1]
Small validation. Reliability and precision were assessed with 26 physician investigators reviewing 12 written vignettes. Responsiveness was assessed in 15 real patients over 6 months, with a mean RI change of 10.5 (95% CI 5.4 to 12). These are small samples.[1]
Conflicting reliability figures. The paper reports an inter-rater reliability of 0.88 in its abstract and 0.89 in its results. Intra-rater reliability was based on only three re-scored cases. Use the paper's figures with these limits in mind.[1]
Scale changed during the study. The prototype scale had a fifth level that could show false improvement. The final scale (used here) removed it. Scores from the prototype cannot be compared directly with this scale.[1]
Training is required. The authors state that trial use requires investigator training and assessment.[1]
Not validated for outcomes. The paper does not show that RI change predicts patient-important outcomes such as survival or organ function over time.[1]
Serum IgG4 is not scored. An earlier version included it. It was removed because many patients in remission never normalize serum IgG4.[1]
Sources: Wallace ZS, et al. Arthritis Care Res 2018;70(11):1671-1678 (reference 1); scoring-rules supplement, September 2018 (reference 3).
How to use it. For each organ site, pick a score from 0 to 3 for the last 28 days. Tick Urgent when the disease needs treatment immediately to prevent serious organ dysfunction: that organ's score is doubled. Tick the flags that apply. Sites you leave unscored add nothing. To clear a score, click it again or press Backspace.
0Normal or resolved
1Improved but still present
2New or recurrent while off treatment, or unchanged from the previous visit
3Worsened or new despite treatment
Damage means permanent organ dysfunction caused by IgG4-RD. Damage and the symptomatic flags are counted but do not change the activity total. The grouping of sites below is for navigation only and does not affect scoring.
Shows the change since that visit.
Brain, eye, and head and neck0 of 12 scored0 pts
Meninges
Pituitary gland
Orbital lesion
Lacrimal glands
Parotid glands
Submandibular glands
Other salivary glands
Mastoiditis / middle ear disease
Nasal cavity lesions
Sinusitis
Other ENT lesions
Thyroid
Chest and blood vessels0 of 4 scored0 pts
Lungs
Aorta / large blood vessels
Heart / pericardium
Sclerosing mediastinitis
Abdomen and retroperitoneum0 of 6 scored0 pts
Retroperitoneal fibrosis
Sclerosing mesenteritis
Pancreas
Liver
Bile ducts
Kidney
Lymph nodes, skin, and whole-body symptoms0 of 3 scored0 pts
Lymph nodes
Skin
Constitutional symptoms (weight loss, fever, fatigue due to active IgG4-RD)
Other involvement0 of 3 scored0 pts
Each entry is counted separately. Name the site, then score it like any other.
About the IgG4-RD Responder Index
IgG4-related disease can cause fibroinflammatory lesions in nearly any organ, and patients are often followed by several specialties. The Responder Index was created so that investigators can assess treatment response in a structured way. Carruthers, Stone, and colleagues built the prototype in 2012 on the approach used for the Birmingham Vasculitis Activity Score, and members of the international IgG4-RD symposium organizing committee refined it in a paper case exercise[2].
The index guides the clinician through disease activity and damage in 25 domains, giving higher weight to manifestations that need urgent treatment or that worsen despite treatment[1]. In the 2018 validation study, 26 physician investigators scored 12 written vignettes after training, and three investigators then followed 15 patients with newly active disease over serial visits. The authors concluded that the index was valid and reliable for measuring response to therapy, and the limitations listed above explain where that conclusion stops[1].
How the score is calculated
Each of the 25 domains (24 organ sites plus constitutional symptoms) is scored 0 to 3 for the last 28 days. Free-text Other sites can be added, and each is counted separately. The total activity score is the sum of the site scores, with the score doubled for any site marked urgent.
Score
Meaning (last 28 days)
0
Normal or resolved
1
Improved but still present
2
New or recurrent while off treatment, or unchanged from the previous visit
3
Worsened or new despite treatment
Worked example. The kidney is scored 2 and judged urgent, so it contributes 2 x 2 = 4. The pancreas is scored 1, so it contributes 1. The lacrimal glands are scored 0 and contribute nothing. The total activity score is 5.
Damage and the symptomatic flags are tallied separately as counts of organs and never added to the activity total[1][3].
Interpreting the result
The source defines no score band and no cut-off for response, so this calculator does not label a total as mild, moderate, or severe and does not call anyone a responder. Use the total as a record of disease activity at one visit, and compare it with earlier visits using the optional previous-total field.
For context only, the 15 patients followed over 6 months in the validation study showed a mean RI change of 10.5 (95% CI 5.4 to 12)[1]. That is an observed average in a small sample, not a threshold.
Common pitfalls
Treating urgency as objective. Urgency is a clinician judgment and the least reliable part of the score. Apply the definition (treatment needed immediately to prevent serious organ dysfunction) consistently from visit to visit.
Scoring imaging that has not been repeated. If judging change would need follow-up imaging that has not been done, the paper says to score the manifestation 2 (unchanged).
Expecting damage to move the total. Damage is recorded for the record. It does not raise or lower the activity score.
Frequently asked questions
What is the IgG4-RD Responder Index?
The IgG4-RD Responder Index (RI) is a structured instrument for recording IgG4-related disease activity and damage organ by organ. Carruthers, Stone, and colleagues developed it in 2012 using the approach behind the Birmingham Vasculitis Activity Score, and Wallace and colleagues validated it in an international multispecialty study in 2018.
How is the total activity score calculated?
Each organ site is scored 0 to 3 for the last 28 days. If the clinician judges that organ's disease to be urgent, its score is doubled. The total is the sum across all sites, including each separately entered Other site.
What counts as urgent disease?
Disease that needs treatment immediately to prevent serious organ dysfunction. The scoring rules define urgency only in general terms, with no site-by-site list, so it is a clinician judgment. In validation, investigators identified urgent disease correctly 76% of the time.
Is there a score that defines a responder?
No. The source defines no responder threshold. This calculator shows the change from the previous visit total and does not classify anyone as a responder.
Does damage change the total score?
No. Damage and the symptomatic flags are recorded and counted, but they do not change the activity total. Surgery beyond fine-needle aspiration is counted as damage by design.
Is serum IgG4 part of the score?
No. An earlier version included it, but it was removed because many patients in remission never normalize serum IgG4.
How was this calculator checked?
Scoring rules were taken from the validation paper and its scoring-rules supplement, then tested against hand-calculated cases covering every score, the urgent doubling, the counts, and reset. Every gap in the source is listed under limitations. The page was reviewed by Mahiar Rabie, MS, MD.
References
1Wallace ZS, Khosroshahi A, Carruthers MD, Perugino CA, Choi H, Campochiaro C, et al.An international multispecialty validation study of the IgG4-related disease responder index. Arthritis Care Res (Hoboken). 2018;70(11):1671-1678. doi:10.1002/acr.23543. PMID 29457382. Source of the domains, scale, and validation figures used here.
2Carruthers MN, Stone JH, Deshpande V, Khosroshahi A.Development of an IgG4-RD Responder Index. Int J Rheumatol. 2012;2012:259408. doi:10.1155/2012/259408. Original development paper for the instrument.
3Scoring-rules supplement (acr23543-sup-0001, version 19 September 2018) accompanying reference 1. Source of the scoring rules for activity, urgency, and damage.
Source and credit. The IgG4-RD Responder Index was created by Carruthers, Stone, Khosroshahi, and colleagues. The scoring form is copyright The General Hospital Corporation, and credit for the instrument belongs to the original authors. This page is an independent educational implementation and is not endorsed by the authors or by Massachusetts General Hospital.
For clinical decision support only. The IgG4-RD Responder Index is a research instrument that requires investigator training in trials. 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 citations, reviewer attribution, scoring explanation, FAQ, and references. Scoring logic unchanged.
Total activity score
0
urgent organs doubled
No sites scored yet
Counts
0Urgent organs
0Symptomatic (active) organs
0Damaged organs
0Symptomatic (damage) organs
Sites adding to the score
Nothing yet. Score a site to see it here.
Reviewed by Mahiar Rabie, MS, MD · AutoimmuneCalc · Last reviewed October 7, 2026