Are you pro procalcitonin?

Clinicians over prescribe antibiotics. I spent several years exploring the risk-averse nature of physicians (specifically ID physicians) when it comes to avoiding treatment failure in diabetic foot ulcer, community-acquired pneumonia (CAP), and CVC bacteremia. Using binary choice contingent-valuation analysis our group determined that ID docs were very risk averse. For example, three of 34 ID physicians found a failure rate of 1% in CAP to be unacceptably high. So how do we acknowledge the risk-averse nature of clinicians, while at the same time safely improving antimicrobial stewardship through reducing over-prescription or shortening duration of therapy?

One possible and much heralded solution was going to be improved diagnostic microbiological tests, such as PNA FISH, which can rapidly detect clinically important (ie you need to alter therapy) pathogens, such as MRSA. These require waiting for positive blood cultures and haven't yet fully caught on, for whatever reason.  Importantly, these micro tests can't tell you if the patient is infected vs. colonized or what clinical syndrome they might have, such as pneumonia. Even a chest xray can't tell you if your patient has pneumonia.  That's why I was cautiously hopeful as I read a meta-analysis by Philipp Schuetz et al. of procalcitonin in directing antibiotic initiation and duration in acute respiratory infection, published online May 9th in CID.

Procalcitonin has gotten a lot of attention recently since it's been found that levels are high in severe bacterial infections but lower in viral or non-specific illnesses. Thus, algorithms that include procalcitonin cut-offs might help target initiation and withdrawal of antibiotic therapy without impacting clinical outcomes. To verify this claim, the authors reviewed 14 clinical trials with a total of 4221 patients to determine mortality, treatment failure and total antibiotic exposure in patients treated under procalcitonin-guided algorithms versus standard therapy. Mortality was similar in both groups (OR 0.94, 95% CI [0.71-1.23]) and treatment failure was slightly lower with procalcitonin (OR 0.82 [0.71-0.97]. Both of these were despite relatively poor-adherence in some of the studies. Importantly, total antibiotic exposure was decreased when using procalcitonin containing algorithms with a statistically significant reduction of 3.47 days. However, sample size was low when limited to ICU patients, so further studies are needed there.

These results do suggest that procalcitonin-containing antibiotic treatment algorithms may have an important role in respiratory tract infection therapy, particularly from a public-health, antibiotic resistance standpoint.  It remains to be seen if algorithms with limited clinical benefit for the individual patient but large potential benefits in terms of stewardship and public health will ever be widely adopted. Physicians are still risk averse, after all. Fingers crossed.

Source: Schuetz P. et al Clin Infect Dis 2012 (online May 9, 2012)

Image source: July 2009, Clinical Laboratory News