Is Prophylactic Hydrocortisone The Magic Bullet For BPD?

Is Prophylactic Hydrocortisone The Magic Bullet For BPD?

I feel like this has been a story in the making for some time. Next to caffeine, the story of prophylactic hydrocortisone must be one of my more popular topics and has been covered more than once before as in A Shocking Change in Position. Postnatal steroids for ALL microprems or Early Hydrocortisone: Short term gain without long term pain. and the last post Hydrocortisone after birth may benefit the smallest preemies the most!  After reporting on this topic about once a year, a recent paper may wrap it all up in a bow for the holidays and present to us the conclusion after all this work on the topic.  I was extremely interested in this topic not just because I believe this therapy may have a future in the standard approach to neonatal care for VLBWs but because I have served on the CPS Fetus and Newborn committee with two of the authors of the paper.  Dr. Lacaze and Dr. Watterberg have an exceptional understanding of this topic and so when they band together with other experts in the field I take notice.  In fact here I am with Dr. Lacaze in case you doubted our history together (we also worked in Edmonton together but that is another story).

An Individual Patient Data Meta-Analysis

If you have read my previous posts then you know the story of why hydrocortisone given over the first 10-12 days of life might help those born before 30 weeks or < 1250g.  In essence the concept is that it has been shown previously that many infants with relative adrenal insufficiency may go on to develop BPD.  If you treat all such infants at risk you could theoretically reduce BPD.  Typically after a few studies examining a similar topic come out, one can combine them in a meta-analysis using aggregate data (averages of effect sizes for the individual studies) and see what the larger sample shows.  Another way to do it though is to go back to the original data and examine the infants at a more granular level allowing a greater identification and control of variables that might influence outcomes.  This is what the authors led my Michele Shaffer did here in the paper Effect of Prophylaxis for Early Adrenal Insufficiency Using Low-Dose Hydrocortisone in Very Preterm Infants: An Individual Patient Data Meta-Analysis.  There were a total of 5 studies on this topic but one study of 40 patients no longer had individual data so was excluded from analysis leaving 4 to look at.  The details of the four studies are shown below.  You can see that the inclusion criteria differed slightly but in general these were all infants up to 27 – 29 completed weeks and 500 – 1250g maximum who were treated with regiments as shown in the table.

 

 

 

 

 

 

What were the results?

Treatment with early low-dose hydrocortisone was associated with greater odds of survival without BPD at 36 weeks PMA after adjustment for sex, gestational age, and antenatal steroid use (aOR, 1.45; 95% CI, 1.11-1.90; I 2 = 0%). Also found were lower individual odds of BPD (aOR, 0.73; 95% CI, 0.54-0.98; I 2 = 0%), but not with a significant decrease in death before 36 weeks PMA (aOR, 0.76; 95% CI, 0.54-1.07; I 2 = 0%). Importantly although death by 36 weeks was not different, a decrease in death before discharge (aOR, 0.70; 95% CI, 0.51-0.97; I 2 = 0%) was found.  Also noted and important was a reduction in medical treatment for PDA OR 0.72 (0.56-0.93)

All of these outcomes sound important but in a subgroup analysis other interesting findings emerged.

When dividing the patients into those less then 26 weeks and those at or greater than that gestational age, the benefits appear to be limited to those in the latter group.  Levels of significance are high once you reach that GA suggesting that issues affecting those at younger gestational ages are less amenable to treatment.  On the other hand one could say that the benefits seen at 26 – 29 weeks GA are relatively strong using a glass is half full approach.  An important outcome worth noting is that while spontaneous intestinal perforation is noted to be a risk with prophylactic hydrocortisone, when you remove indomethacin from the equation the risk disappears.  For those units using prophylactic hydrocortisone one would likely need to choose between the two but if you are like our unit where we don’t have that option this may be one strategy to consider.

In terms of risk to giving such therapy the big one noted in the paper was an increase in risk for late onset sepsis.  Interestingly, this was limited though to the group under 26 weeks GA.  In essence then the messaging would appear to be that under 26 weeks there may be less benefit to such treatment and therefore the increased risk of late onset sepsis without such benefits on BPD would suggest not using it in this GA group.

Where do we land then?

It would be easy to cast this aside I suppose as the group you are most worried about (22-25 weeks) doesn’t seem to really benefit but has a risk of late onset sepsis.  That leaves us though with the group from 26-29 weeks.  They do seem to benefit and may do so to a significant degree.  They do develop BPD and to be honest we don’t have much outside of trying our best to use gentle ventilation to ameliorate their course in hospital.  It is worth noting that the one group that does seem to show the greatest benefit are those exposed to chorioamnionitis.  It is this group in particular that may be the best target for this intervention and I gather this has been discussed at a recent EPIQ meeting.

If one says no to trying this approach then the question that needs to be asked is whether doing nothing for this group is better than supporting them with hydrocortisone?  If your centre’s rates of BPD are top notch then maybe you don’t want to add something in.  If not though maybe it is time to rock the boat and try something different.  Makes me think of the following saying and might be something to think about.

 

Early Hydrocortisone: Short term gain without long term pain.

Early Hydrocortisone: Short term gain without long term pain.

In our journey as Neonatologists and interdisciplinary teams we are forever seeking to rid or at least reduce the plague of BPD in the patients we care for.  The PREMILOC trial was a double-blind, multicenter, randomized, placebo-controlled trial designed to test just that concept by introducing a low dose of hydrocortisone within 24 hours of birth. They   enrolled infants born between 24 – 26+6 weeks of gestation  and assigned them to receive either placebo or low-dose hydrocortisone 0.5mg/kg twice per day for 7 days, followed by 0.5 mg/kg per day for 3 days.  The trial has been the subject of a previous post A Shocking Change in Position. Postnatal steroids for ALL microprems?  Although the trial was stopped early due to financial concerns the authors demonstrated a 9% reduction in BPD using this strategy.  The theory here in part is that the presence of hydrocortisone reduces inflammation and that this in turn may allow for better growth of lungs with time.

Why Not Adopt The Results Based on These Fantastic Results?

Steroids in preterm infants have a bad name.  As discussed in previous posts on the topic the concern in all trials has been the potential impact of such medications on the developing brain. A nice summary of these concerns can be found in a paper in the CMAJ by the other “Canadian Neonatal Blogger” from 2001 in which he quoted the risk of cerebral palsy increasing from about 1 in 6 babies to 1 in 3 if babies born at < 28 weeks were exposed to postnatal steroids.  Neurodevelopmental impairment overall would change from 1 in 4 to 1 in 3 if such exposure occurred.  This paper and others expressing concerns over the effect of postnatal steroids led to a change in practice from more ubiquitous use to one restrained to only in those cases where the patient was nearing the end of all other options.  This meant holding out for such therapy until such patients were at 90% or more O2 and on high mean airway pressures.  Although not formally studied I was very concerned at the time with using this approach as I felt it was a “fait de complet” that they would either die or have significant developmental impairment should they survive due to the complications of having such severe BPD.  It is critical to note though that the outcomes from these long term studies were in infants exposed to much longer courses of dexamethasone and at high doses that are used today.

Over the years with the development of the DART protocol and other more gentle approaches to steroids we as a group relaxed and certainly rescue courses of lower dose steroids have crept into practice when patients seem to be “stuck” on the ventilator.

Drumroll Please…

The results of the PREMILOC follow-up study are now here and in short they look good.  Patients were followed up at an average age of 22 months and included a medical history, anthropometric measures, respiratory status, standardized neurological examination based on specific definitions of disabilities, and quantitative neurodevelopmental assessment using the revised Brunet-L.zine (RBL) scale.  Follow-up was 93% in the hydrocortisone and 90% in the placebo arm which is important as we need not worry about the missed patients influencing the results to a significant degree if they had been included.  Although some post-hoc analyses were done what I am most interested in is the primary outcome which is shown below.

premiloc followup

There was no difference in either neurodevelopment overall or any of the subcategories.  This provides a great deal of reassurance to those who provide steroids this way.  There will be those however that argue the study is too small.  While a larger study might be better able to address whether there is a small difference in outcome I don’t think we will see one anytime soon.  It is one of the challenges we face in Neonatology.  Unlike the adult world with studies of thousands of patients, due to the small number of patients born at <28 weeks it is always a challenge to recruit into such large volume trials.  We can compare trials by doing meta analyses or systematic reviews and perhaps that is where we will head with this study although given that different steroids will have been used (thinking dexamethasone as in the DART study) this will always be left open to question.

Is it worth it?

I suppose the real question here is the following for a parent to consider. “Would you like your baby to receive hydrocortisone shortly after birth with a 7% reduction in the risk of BPD at 36 weeks bearing in mind that although we don’t think there is an impact on long term development we aren’t certain yet”.  

I guess to answer this question you need to think about the first part of the question.  Is BPD at 36 weeks a good outcome to look at for benefit?  The Canadian Neonatal Network has recently called for a rethink on this The New BPD That Matters.  It turns out that it is 40 weeks and not 36 weeks that has the greatest prediction for respiratory morbidity after discharge.  If you were to move the goal post to 40 weeks from 36 I strongly suspect one would see the 9% reduction in BPD as shown in the PREMILOC trial vanish.  If that is the case, would a slightly earlier extubation time be enough to motivate families to take the plunge?

Although I often cringe at the expression “more trials are needed”, I think at least a combination of studies to achieve greater confidence in outcome may be needed.  Barring that, we might just have to sit tight and accept that while there may be a little bit to be gained with the use of the PREMILOC protocol it may just not be enough to be clinically warranted at this time.  May want to wait for the next big thing to tackle BPD…