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Wednesday, December 14, 2016
Lupus Nephritis classification: Does it help us?
I recently went to a talk by Stephen Korbet on Lupus Nephritis and it got me wondering on if the current way of classification of lupus nephritis works or not?
MPGN- old way of classification was EM based but the recent updated IF based classification is very clinical and aids the clinician in treating the disease better as a root cause is identified.
In lupus, the story starts back in 1970s and eventually leading to the WHO classification and then the updated ISN classification. A recent review published in JASN in 2015 summarizes the history and concerns regarding the classifications. The suggestions to improve are more detailed and pathology related and I am not sure if they will help clinically.
What might help a nephrologist help treat the lupus nephritis patient?
1. Is the lesion Proliferative?- segmental or diffuse- most of us will treat. Only context of not treating will be the IFTA present on the biopsy- so does it matter if its segmental or diffuse? as treatment is either MMF or cyclophosphamide anyway.
2. Is the lesion crescentic? - yes this matters to us-- as most crescentic GN( RPGN) and specifically lupus have been excluded in most trials- so treatment might be leaning towards cytotoxic agents and not standard therapy.
3. Is it a podocytopathy ( would like to include membranous GN in this section)- More and more we are seeing MCD, FSGS with this entity and treatment might be slightly different as some of them respond faster with a steroid based regimen.
4. Is there a second entity with it?- ANCA disease or TMA?- as treatment might then entail pheresis and or a different prognosis.
I think the talk by Korbet hinted towards this but not sure which direction the field will go but it's time that we have a less confusing classification but more meaningful one that helps the nephrologists treat the disease better.
What do others think?
The trouble with all Glomerulopathies (not only Lupus) is that our knowledge of treatment outcomes is the result of observations from biopsies classified by the old classification protocols. In my clinical experience I have seen GNs that shouldn't respond to any regime, responding to steroids and in contrast, GNs that should be easily treatable with simple drug combinations, not responding to anything. That of course makes sense since our knowledge of outcomes is purely statistical, not patho-physiological for each case. I'm not sure if we need a different pathological approach, or a tottaly different approach based i.e. on biochemical markers for different diseases that are still unknown to us.
ReplyDeleteAs a pathologist, I share the similar frustration with nephrologist. For example, proliferative lupus is based on % of active lesions. In practice, focal (class III) vs diffuse; (IV) segmental (S) vs global (G) are highly biased by sampling error. I am not sure these subclassifications will help for clinical decisions. Also, among active glomerular lesions, I felt segmental necrosis and cellular crescents should be weighted more over others, at least should be treated more urgently. Large multiple center clinical studies of renal biopsy may help to refine the classification, like recent article about crescent in IgA nephropathy. Biochemical markers could be another route, as in transplant filed.
ReplyDeleteA Multicenter Study of the Predictive Value of Crescents in IgA Nephropathy. J Am Soc Nephrol. 2016 Sep 9.