Tiotropium Kills (or Does It?)

Several weeks ago, I noted that inhaled anticholinergics can increase men's risk for urinary retention.  Upon rereading my May 27, 2011 post, I realized that I didn't really mention any examples of these inhaled anticholinergics, just the class name.  But the fact is tiotropium, the newest amongst others, has some side effects of which we need to be aware.

But since it makes breathing easier for those patients suffering from chronic obstructive pulmonary disease (COPD) or emphysema, I still thought that I would offer it my male patients and just be more forceful & emphatic in my warnings.

However, in a study published last week, researchers in the UK linked the use of tiotropium mist for COPD to a 52% greater relative risk of death compared to placebo.  Ouch!  My patients can tolerate an increase risk of urinary retention but greater risk of mortality in the 6th leading cause of death?  No way!

Of course I had to dig deeper.  It turns out that in the UK, tiotropium is available in 2 forms:  powdered & mist.  Only the former is sold here in the States but it was the latter that was studied in 3,686 patients randomized to tiotropium vs 2,836 randomized to placebo in an analysis of 5 double blind trials.  First things first.  This study of studies has a reasonable number of subjects.  Second, it's probably not applicable to us here in the States because the version of the drug studied isn't sold here.

But go read the accompanying editorial when you get a chance.  The editorialist does a wonderful job of explaining the difference between relative risk (46% by his calculations) and absolute risk (0.8%).  He goes on to explain that, yes, while one's relative risk is greater as a result of tiotropium, one's overall risk of death is still rare.  We'd need to offer placebo for 1 year to 1,000 patients  in order to harm 18 patients.  And we'd need to prescribe tiotropium for 1 year to 1,000 in order to harm 5 patients.  The number needed to harm calculates out to treating 121 patients in order to harm 1 patient.  So perhaps we don't need to throw out our powdered tiotropium after all (or is that yet?).  As always, we need to analyze more closely what's published in order to get the whole story.