This study in the New England Journal of Medicine is going to change how we treat spontaneous pneumothorax. If you haven’t read it, you should.
(Disclaimer: the lead author, Dr Simon Brown is a colleague of mine at the Royal Hobart Hospital. He is bigger than me and knows where I live. Hmmmm….)
By way of background, there are conflicting guidelines regarding the treatment of primary spontaneous pneumothorax. The Americans are quite aggressive with intervention, the British less so. Any time you see such variation, it usually means there is no high-quality evidence to inform practice.
Fortunately, we now have that evidence.
The Primary Spontaneous Pneumothorax (PSP) trial was a prospective randomised open-label non-inferiority study that enrolled 316 patients in 39 hospitals in Australia & New Zulund over 6 years.
They included stable patients between the ages of 14-50 with at least a 32% (sum of interpleural distance greater than 6cm) primary spontaneous pneumothorax.
Those randomised to “intervention” had a <12 French Seldinger style chest tube placed. They got a repeat chest x-ray in one hour. If the lung was re-expanded and there was no air leak, they clamped the tube. Another x-ray was taken 4 hours later. If all was fine, the tube was pulled and the patient discharged. If not, they got admitted.
The “conservative” arm was observed for 4 hours and a repeat chest x-ray was taken. If they did not require oxygen and they were walking around comfortably, they could be discharged. However, intervention could be allowed for if the patient had clinically significant symptoms despite adequate analgesia, couldn’t walk, unwilling to continue, became unstable or if the chest x-ray was getting worse.
The primary outcome was full lung expansion by 8 weeks. There were lots of arguably more important secondary outcomes.
As expected, patients were generally young, male and thin. Half were smokers.
Mean pneumothorax size was 65%! Holy crap… that’s big.
For the primary outcome, 98% of the intervention arm had full lung re-expansion at 8 weeks vs. 94% in the conservative arm. This was within their prespecified non-inferiority margin of -9% as such, this is a positive study.
However, even more impressive are the secondary outcomes in favour of a conservative approach.
85% of patients randomised to conservative management got no intervention. The intervention arm had many more adverse events (26% vs. 8%) mostly related to the chest tube. Mean time to resolution of symptoms was 15 days in both groups. Recurrent pneumothorax was double in the intervention arm; 16% vs. 8%.
Median hospital length of stay was 3.8 days in the intervention group compared to 0.2 in the conservative arm!
All of this is quite a good argument for us to change our practice.
For what it is worth, the manuscript goes into length regarding the limitations of loss to follow-up. Even going so far as to perform an analysis assuming all of them were treatment failures making this study “fragile.” While perhaps technically correct, I think this was overzealous peer review that was ultimately biased.
A 26-year-old male, who got no treatment and feels fine is probably less likely to follow up as directed. However, patients in the intervention arm (who got painful tubes and spent 4 days in hospital) were more likely to return for the 8-week visit.
What’s the take home point?
Looks like we’ll be doing less chest tubes in stable patients with primary spontaneous pneumothorax.
Bummer… I like putting in chest tubes.
Brown S.G.A, Ball E.L, Perrin K, Conservative versus Interventional Treatment for Spontaneous Pneumothorax. N Eng J Med. 2020;382:405-15. [link to article]