ACCORD and AVANCE: Good News for Type 2 diabetes...really.
Posted Jun 24 2008 12:08pm
At least according to what's out there in the media and in the medical blogsphere on the two large recent diabetes trials presented at the ADA and published in the NEJM, in my opinion everyone seems to have missed the big picture, and the good (not bad) news about diabetes.
EvenDr. Centor, in an excellent commentary on how the findings of these studies relate to problems using performance measures (which I agree with), does not mention anything positive..
The issue at hand is that though we use the hemoglobin A1c, a measure of overall sugar control, as a target for diabetes treatment which has been proven to prevent small vessel (microvascular) diabetes complications such as blindness and kidney problems, we have never proven (with scientific rigour) that it prevents larger vessel (macrovascular) disease such as heart attacks and stroke. The thought was that if there was a large study that treated even more aggressively (target A1c is usually recommend at less than 7%, normal A1c which is not currently a target is less than 6%), this might prove the point.
The Action to Control Cardiovascular Risk in Diabetes Study(ACCORD) looked at 10,251 type 2 diabetics (more than a third with a prior stroke or heart attack) with a median hemoglobin A1c of 8.1% and randomized them to receive intensive therapy (targeting an A1c below 6.0%) or standard therapy (targeting an A1c from 7.0 to 7.9%). At a year the groups achieved A1c's of 6.4% and 7.5% respectively, but after several years there was not real difference in combined hearts attacks, strokes or deaths in either groups (352 vs. 371), there was a statistical difference in death (257 vs 203), and the intense arm was stopped early.
TheAction in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation(ADVANCE) trial was a similarly designed European study 11,140 patients with type 2 diabetes, except the targets for the intense group was less than 6.5% and not less then 6.0%. Interestingly the A1c's achieved by both sets of patients was nearly identical to ACCORD (6.5% vs.7.3%). The also found no difference in combined heat attacks, strokes and deaths; but fortunately found no difference in deaths from the intensive group as seen in ACCORD.
All of the reports (linked to above) point out that these studies failed to prove that aggressive treatment makes any difference in heart attacks or strokes, and in the case of ACCORD seemed to (surprisingly) cause more heart attacks. However, they are missing a majorly important finding of both studies.Treating diabetes aggressively is quite effective!
We already knew about microvascular disease, and ADVANCE showed us that this still holds to be true, with substantial reductions in early kidney disease. However, what is being overlooked is that both groups in both studies did much better than expected. In ACCORD, to show a statistical difference, the study enrolled enough patient based on research about event rates in diabetics. Based on their original calculations, there should have been about 500 heart attacks or strokes in the standard care group. However, there were only 371 in the standard care group, and even fewer in the intense arm. Death calculations were not published in the article, but I would imagine that though the death rate was (seeming paradoxically) higher in the intense arm, death rates in both arms were likely much lower than one would typically expect. Similarly, in ADVANCE, the found that after a mean of approximately 3 years of follow-up, it became apparent that the event rates (in the two groups combined) were lower than expected, and had to adjust their protocol, extending it by a year. Fewer events than anticipated in two very large studies seem like good news to me.
Why would these studies find lower event rates than expected? Likely because of more aggressive overall treatment. Not just lowering sugar, but lowering blood pressure and cholesterol levels with medications. In fact, because cholesterol and blood pressure reduction may be such important factors for macrovascular complications in diabetics, it might take a greater number of patients and a longer amount of time (not lowering the sugar to normal) to show the true impact, which is likely beneficial. Thus, patients with Type 2 diabetics should be relieved and not fearful of these reports. We have better medications that are more effective at lowering not only sugar, but also blood pressure and cholesterol and together (along with diet, exercise, and an aspirin) lower bad outcomes including heart attack and stroke, then we were previously able to accomplish just a few short years ago.
Why the difference in deaths? There will be a lot of opinions about why patients in the intense arm of ACCORD had an increase number of deaths and ADVANCE did not. Here is mine.
The first two of the three the editorials which accompany both studies published in the NEJM note that most of the patients in the intense group were on a TZD like Avandia (the 1st and 3rd editorial both cite Dr. Nissen's well publicized/criticized meta-analysis about cardiovascular risk with Avandia-also published in NEJM), together suggesting that maybe the increased death rate was due to this class of medications. However, we know that TZD use can not account for the differences in outcomes in ADVANCE because as I have noted in aprevious poston this study, when the study was stopped, given the concerns regarding Avandia, the NIH specifically looked for links to Avandia andfound none. (It is interesting that this is not highlighted in article.) In fact, since most patients in the intense arm were taking a TZD like avandia, and heart attacks were lower, and increase in deaths could not be attributed to rosigliataozne, this should be most reassuring (see, more good news).
If not Avandia, then why the increased death rate in ACCORD but not ADVANCE. The second NEJM editorial points out that the rate of A1c drop was much more rapid in ACCORD then ADVANCE (1.4% within 4 months vs. 0.5% at 6 months respectively). How did they achieve such a rapid drop in one study, but not the other? This is reiterated in the discussion section of ADVANCE.
"Mechanisms speculated to underlie the excess mortality found with intensive glucose control in the ACCORD trial include the initial level of glycated hemoglobin, the degree and pace of glucose lowering, and the treatments used to achieve such lowering.20,22In the ADVANCE trial, no subgroup of participants was identified to have evidence of an adverse effect of intensive glucose lowering on major vascular outcomes, including the subgroup with an initial median glycated hemoglobin value similar to that in the ACCORD study population.21"
Exactly how doctors tried to achieve normal A1c levels in Type 2 diabetics was not clarified in the ACCORD publication, an in fact, investigators could use their own clinical judgement. However in ADVANCE, this is spelled out clearly and in step wise fashion:
1. Add gliclazide (and SU like glyburide or glimeperide, but not used in the US) 2. Increase the dose of gliclazide MR (30-120 mg) 3. Add or increase the dose of metformin; 4. Add orincrease the dose of thiazolidinedione; 5. Add or increase the dose of alpha-glucosidase inhibitor; 6. Add bed time insulin therapy; 7. Add a full insulin regimen or increase the dose of a full insulin regimen
What you see hear is that in ADVANCE, adding insulin was the last resort in a stepwise fashion to get the A1c under 6.5%. Again, we don't know exactly what happened in ACCORD, but if you look at thedifferences in medicationsnot only was there more TZD's in the intense group, there was a large difference in insulin use (77% in the intense group vs. 55% in the standard group). In ACCORD the rates of insulin use was 40% in the intense group and 24% in the intervention group. Hypoglycemia and weight gain (which are both caused by insulin) were reported as significantly increased adverse events in ACCORD.
Thus, I would argue that one of the reasons you might actually cause harm in intensively trying to lower sugar, is when you need insulin to get to that goal. This suggest (contrary to the ADA guidelines) that targeting to an A1c of less than 7.0% should be done with multiple medications, and not with insulin. In fact, it might be better to reserve insulin for those patients with an A1c of more than 8%, despite multiple oral agents (again, contrary to ADA guidelines).