acpa rf cv

1. Journal club
12.1.2021
Ritasman Baisya

2. Published in Arthritis & Rheumatology in October , 2020

3. Introduction
• RA patients have increased risk for CV disease
• ACS , stroke , CV mortality - increased after RA diagnosis
• Risk of CV events in RA per se remains elevated
• Increased risk cant be fully attributed to traditional risk factors
• Shared etiology between Ra and CV risk is important
• Disease activity , high ACPA level increase risk
• ACPA may also present in atherosclerotic plaque
• RF also linked to CV risk

4. Unclear issues
• It remains unclear whether any particular ACPA sub-specificity linked
to CV risk
• ACPA load (number of ACPA sub-specificites expressed ) linked to CV
risk
• Association between ACPA load with different CV events is unknown
• Independent role RF isotypes in CV risk remains unknown

5. Objectives
• Association between presence and levels of anti CCP2 , specific ACPAs
& combination with CV events in RA
• Association between RF isotypes and the risk of CV events
• CV events defined as ACS , stroke , CV related death , composite end
point of MACE
• Patients were followed up for CV events from time of diagnosis

6. Methodology
Study designs
• Swedish Epidemiological investigations of RA ( EIRA ) study includes RA patients –
most from Sweden , 9% in other European countries , 3% other parts of world
• Newly diagnosed RA patients by 1987 criteria ( within 1 year of symptom ) from
1996 to 2009 were selected
• From National patient register , SRQ , LISA for event details , clinical presentation ,
Income details respectively recorded ….

7. Serological data
• Serum samples obtained from EIRA participants
• Anti CCP2 assay was done by centrally using commercial assay
• <25 AU/ml , 25-75 , 75-1500 , >1500 AU/ml
• <25 – negative , >75 – high positive
• ACPA sub-specificities centrally tested on a custom-made microarray ( Thermo fisher
scientific )
• 20 ACPA sub-specificities are included
• IgA , IgM , IgG isotypes analysed by EIA immunoassay on a Phadia 2500 instrument

8. Follow up and outcomes
• Follow up data on all individuals from time of inclusion to first event
of ACS , CV related death , stroke , MACE
• Follow up was censored at time of death , emigration , end of study
period (Dec 31 , 2016 )
• NPR and cause of death registry were used

9. Statistical analysis
• All ACPA sub-specificites with frequency > 10% in sample were included
• Auto-antibody load is also defined
• Spearman rank correlation for calculating anti CCP2 levels and number of specific
auto –antibodies
• For each outcome incidence is measured
• Cox hazard model is used for association of CV events and antibody load
• Each sub specificity of ACPA was analyzed with separate model

10. Exploratory analysis
This analysis done to investigate impact of adjustment for each of 3 CV
event determinants ( smoking , income , RA disease activity at
diagnosis ) on association of RA specific auto-antibodies and CV end
points

11. Results
• 2814 patients with incident RA and with information of all antibodies were
considered.
• Median age – 51 yrs ( IQR-18)
• Median follow up from time of RA diagnosis - 13 yrs ( IQR- 6.5)
• 65% CCP2 positive , 57% IgM –RF positive
• During follow up – first occurrence of CV event recorded

13. First occurrence of ACS events
Events - first occurrence Numbers Person years
ACS 147 4.3 / 1000 person years
Stroke 141 4.1 / 1000 person years
CV related deaths 87 2.4/1000 person years
MACE events 313 9.4/1000 person years

14. Association of ACPA and CV events

15. Specific ACPA sub- specificity
• 17 auto-antibodies had prevalence > 10 % in samples
• Fil 307–324 (CCP-1), Vim 60–75, Vim 2–17, Fibβ 36–52, Fibα 563–583, Fibα 580–
600, Eno 5–21 (CEP-1), Fib α621–635, Fib α36–50, Fibβ 60–74, Ptm13, Ptm36,
Pept-Z1, Pept-Z2, Pept-1, Pept-5, and Bla26.
• Borderline or statistical significant association between number of sub-
specificities expressed and CV event risks

16. Load of ACPA sub-specificities and CV events

17. ACPA sub-specificity and CV risk
• No single ACPA sub-specificity was associated with all 4 CV outcomes
• Anti -CEP1 –significant association with ACS
• 10 sub-specificities significantly associated with stroke ( Fibbeta – highest
association )
• CV related death – 5 auto-abs significant association
• MACE – 9 auto-abs associated

18. Correlation structure among
the 17 anti-citrullinated sub-
specificites among 2814
Swedish patients diagnosed
with rheumatoid arthritis
1996-2006.

19. Association between ACPA sub-specificity and CV events

20. RF isotypes
• IgM-RF – significant association with stroke ( HR- 1.42 ) and MACE ( HR- 1.4)
• IgA-RF- significant association with increased CV related death ( HR- 1.88 )
• IgG -RF – not significant association with any cardiac events

21. Result of exploratory analysis
• CV death risk in IgA & IgG RF positive with never smoker is low
• IgG-RF negative with never smoker – rate of CV related death 0.4 per 1000 person
years
• IgA RF negative wth never smoker , rate of CV death – 0.44 per 1000 person
years
• After adjusting smoking , IgA-RF & CV related death and IgM-RF & MACE remain
significantly increased

22. Analysis stratified by
smoking status

23. Hazard ratio (HR) adjusted for smoking status (never/ever) with 95% confidence intervals (CI) for ACS, stroke, CV death and MACE for CCP2, CCP2 titer,
number of ACPA specificities expressed, load of specificities, among the 2,531 patients with data on smoking status followed for CV events from RA
diagnosis.

24. Subpopulation analysis
• 1762 individuals ( 63%) had information on smoking , income , initial
RA disease activity
• Income , but not DAS28 associated with all outcomes except stroke

25. Presence and hazard ratio (HR) with 95% confidence intervals for the three covariates
in the exploratory analyses and their association to ACS, stroke, CV death and MACE
respectively, among the 1,762 patients with RA with data on all three included
covariates

26. Discussion
• ACPA positivity is marker for several CV end points
• These association trended toward higher ACPA level
• Increased number of ACPA subspecificity causing more CV end points
• No clear pattern of strong association with particular ACPA subtype
• IgM –RF associated with stroke and MACE , IgA-RF linked to CV related mortality
• Association decreased or disappeared when analysis are adjusted for smoking ,
initial disease activity , SES

27. Comparison to other study
• Ajeganova et al compared the association between the presence of
anti-CCP2 or RF and mortality across 3 RA cohorts, and found
associations with CV-related mortality with an effect size similar to
this study
• Present study includes levels , sub-specificities of ACPA , isotypes of
RF

28. Strength of the study
• Assessing the levels of anti-CCP2, as well as 17 different ACPA sub-specificities and IgA-
and IgG-RF on CV events
• Associations of these autoantibodies applied across several CV clinical fatal or nonfatal
phenotypes, rather than being merely markers of increased overall mortality
• Strong correlation between antiCCP2 level and number of sub-specificities expressed.
• These associations vary across RF isotypes, where IgM-RF was associated with several CV
disease types, but IgA-RF was more distinctly associated with CV-related mortality

29. Strengths
• Identification of, and prospective, complete, and independent follow-up of a large
cohort of patients newly diagnosed as having RA
• CV end points were all based on validated and robust definitions.
• Centrally analyze the serum samples obtained at baseline, thereby minimizing
inter-assay/inter-reader variability, selection bias, or reversed causality
• For robustness of the data, findings might be generalizable to other countries.

30. Limitation
• Missing data
• Limited means to adjust for certain CV risk factors such as lipid
profile, family history of CV disease, physical activity, hypothyroidism
• This study did not have data to address the impact of the disease
course on the outcomes

31. Critical appraisal

32. Are the results of study valid ?
• Clearly focused issue is present
• Population – Swedish patients with new onset RA between 1996 -
2009 , part of EIRA study
• Exposure – Anti CCP2 antibody , its load , 20 sub-specificities , RF
isotypes
• study tried to detect effect of the antibodies over CV related
morbidity and mortality events
• Outcomes are – CV end points – ACS , stroke , CV related death ,
MACE

33. Was the cohort recruited in an acceptable way?
• Newly diagnosed RA patients from Swedish EIRA study- a large cohort
• In total, 18 study centers reported cases of RA to the study
• All cases were assessed and diagnosed by a rheumatologist.
• who had clinical follow-up data from the Swedish Rheumatology
Quality (SRQ) register until 2013.

34. Was the exposure accurately measured to minimise bias?
• Serum samples obtained at baseline are centrally analyzed , thereby
minimizing interassay/interreader variability, selection bias, or
reversed causality
• All the study subjects has undergone same procedure
• Level of CCP2 ( load) , ACPA sub-specificity and isotype of RF were
accurately measured to know their effect on CV outcome

35. Was the outcome accurately measured to minimize bias?
• Using NPR and cause of death registers , follow-up data on all
individuals was obtained from the time of their inclusion in the EIRA
study until a first event of ACS, CV-related death, stroke, or MACE,
defined according to a hospitalization listing with a relevant ICD-10
code
• Associations of these autoantibodies applied across several CV clinical
fatal or nonfatal phenotypes, rather than being merely markers of
increased overall mortality
• CV end points were all based on validated and robust definitions

36. Have the authors identified all important confounding
factors?
• No
• Smoking , income , disease severity were potential confounders and
CV event determinant
• Exploratory analysis was performed to investigate the impact of
adjustment for each of these events
• Analysis was performed stratified by smoking status
• But , these data were missing for few population leading to
adjustment in smaller population than original one
• Other confounders like lipid profile , HTN , DM , family history of CV
disease were not adjusted

37. Was the follow up of subjects complete enough?
• Yes , it was prospective , complete , independent follow up of a large
cohort of patients newly diagnosed as having RA

38. Was the follow up of subjects long enough?
• It is a long follow up from 1999 to 2016

39. What are the results of this study?
• ACPA positivity significantly associated with CV events –
• Extreme level of ACPA associated with significant stroke , CV related
death , MACES
ACS stroke CV related death MACE
1.46 ( 1.03-2.06) , 0.035 1.47 ( 1.03- 2.10) , 0.034 1.48 ( 0.94-2.31) , 0.087 1.34 ( 1.06-1.7) , 0.014
k
ACS stroke CV related death MACE
Not significant 1.72 (1.05–2.81) 0.031 2.27 (1.28–4.03) 0.0053 1.52 (1.09–2.12) 0.014

40. Results of the study
• IgM-RF – significant association with stroke ( HR- 1.42 ) and MACE (
HR- 1.4)
• IgA-RF- significant association with increased CV related death ( HR-
1.88
• After adjusting smoking , IgA-RF & CV related death and IgM-RF &
MACE remain significantly increased

41. How precise are the results?
• Confidence interval are narrow and not crossing 1 indicating precision
of the result

42. Can the results be applied to the local population?
As the population size is robust , it may be applicable to the local
population

43. Do the results of this study fit with other available
evidence?
• Yes

44. What are the implications of this study for practice?
• Anti CCP2 level associated with CV events
• Higher the load of ACPA , more will be chance of CV events
• IgA –RF associated with CV related death
• Even after smoking is adjusted , ACPA load and isotype of RF has
association with CV events