24 February 2011

Avastin Paper in New England Journal of Medicine (BEAT-ROP)

I read the Avastin paper and like all studies it is imperfect. I would say more imperfect than the elegant ETROP, CRYO-ROP or STOP-ROP studies (note my personal bias here).  Nonetheless it is a major effort and accomplishment.  Looking at the literature regarding avastin in diabetes and ROP, and listening to the presentations of my many colleagues about their experience using avastin has persuaded me that that avastin has a strong positive effect on the fibrovascular proliferation of ROP.  Moreover, it is certainly much easier and less stressful to perform and locally safer than laser.  It is in many ways more conservative than laser

My real worry is that the late disease seen after the outcome measurement may lead to significant complications in some patients.  In my experience which admittedly is in extreme cases and salvage after previous laser failure, I have seem many late recurrences that would be missed by examination at 55 weeks PMA. In the study, the average treatment in zone 1 was about 35 weeks and the interval to recurrence was around 20 weeks, so at 55 weeks there would be many recurrences yet to see.  I am unhappy to leave large areas of non-perfusion in the periphery and this may be a late source of serious complications.

Now for my particular questions:
  1. What was the definition of posterior zone 2?  Posterior zone 2 is not an ICROP term.
  2. Was anterior zone 2 treated by laser or observed.
  3. How was the author analysis done and what happened if the data sheets and photos did not line up for zone, stage or plus or recurrence. 
  4. How was confirmation done
  5. Need exact definition of recurrence with photographs.  Use of recurrence is hard to compute because in ETROP you had an outcome that was structural and I am not sure, how it was defined.  How about persistence?  How about 2 week skips lesions?  How did CRYO-ROP or ETROP allow estimate of recurrence after laser? Why use this outcome measure, as opposed to previous studies.
  6. What is evidence for inflammation from laser causes amblyopia in second eye?
  7. What does the author mean by laser causing destruction of full thickness retina?
  8. Why was the outcome endpoint changed and what was the implication for statistics?


Clearly, more work remains. I think avastin can be a tremendous tool, but it is new and caution is still very much required.   We still know very little.  I hope that the patients that get avastin will have very careful examinations weekly or every two weeks until 6 month corrected and then every 2 months until 9 months corrected.  If there is a area of non-perfusion follow up need to continue for a few decades.  Regardless of my questions avastin is now a proven alternative to laser, I would recommend laser for any oddly behaving eyes after avastin until there is more experience.

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