Effect of procalcitonin-based guidelines vs standard guidelines

on antibiotic use in lower respiratory tract infections: the ProHOSP randomized controlled

trial.

JAMA. 302(10):1059-66. (Sept 2009)

Ria Dancel, MD

11/13/2009

Question: In adults with lower respiratory tract infection (LRTI), is antibiotic treatment based on

a procalcitonin driven algorithm inferior to treatment based on current guidelines, in terms

of adverse events?

Rationale• Antibiotic overuse – we all know the pitfalls: resistance,

cost, adverse events, C. Diff• 75% of patients with LRTI are prescribed antibiotics

despite predominantly viral etiology• Procalcitonin (PCT) is the precursor of calcitonin.

– Low or undetectable in healthy subjects– Increases in proportion to severity of bacterial disease (infection,

septicemia, meningitis)– Falls quickly in response to appropriate antibiotic therapy– Most importantly, PCT remains low in viral illness, making it a

unique acute phase reactant that can potentially distinguish bacterial from viral infections

Prior studies have suggested that algorithms using PCT cutoffs have decreased antibiotic use but these studies were small and insufficiently powered to show whether they caused more complications

Study Design• Investigator initiated, multicenter, noninferiority

RCT• 6 tertiary care centers in Switzerland• Duration from 10/2006-3/2008• Power:

– Based on previous intervention trials, authors assumed overall adverse outcome risk of at most 20%

– Planning committee agreed that cut-off for inferiority would be risk greater than 27.5%

– Minimum sample size calculated to be 1002 patients to achieve 90% power

• Randomized concealed via centralized website

Inclusion criteria

• 18 years or older, from community or nursing home

• LRTI < 28 days in duration– 1 respiratory symptom (cough, sputum

production, dyspnea, tachypnea, pleuritic pain)

– PLUS 1 auscultory finding (rales, crepitation)– OR 1 sign of infection (fever > 38, shivering,

WBC > 10K or < 4K)

Definitions

• CAP = LRTI with new infiltrate on CXR

• COPD defined by postbronchodilator spirometric criteria set by the Global Initiative for Chronic Obstructive Lung Disease (GOLD)

• Acute bronchitis = LRTI in the absence of an underlying lung disease or focal chest signs and infiltrates on chest radiograph

Exclusion criteria

• Inability to give written consent due to language restriction or dementia

• Active IVDA• Severe immunosuppression other than

corticosteroid use• Life threatening comorbidities leading to

possible imminent death• HAP (development of PNA > 48 hrs after

admission or within 14 days of recent hospitalization)

• Chronic infection necessitating antibiotic use

Study protocol for intervention group (PCT

group)• PCT levels were communicated to physicians caring for

patients allocated to PCT group along with treatment recommendations based on following protocol

– PCT < 0.1 Abx strongly discouraged, remeasure PCT in 6-24 hrs

– PCT 0.1 – 0.25 Abx discouraged, remeasure PCT in 6-24 hrs

– PCT 0.25 – 0.5 Abx encouraged, remeasure PCT on days 3, 5, 7

– PCT > 0.5Abx strongly encouraged, remeasure PCT on days 3, 5, 7

– If abx were started, they were discontinued according to the same cutoffs

Study protocol for intervention group (PCT

group)

Study protocol for control group

• For CAP:– Abx encouraged for 5-10 days– Abx for 14 days for Legionella CAP– Abx for at least 10 days in necrotizing CAP

• For COPD:– Abx encouraged for 5-10 days if pt had severe COPD– Abx encouraged for 5-10 days if pt had purulent sputum + either

increased dyspnea OR increased sputum volume

• For acute bronchitis (no focal signs, no underlying lung dz):– Abx discouraged UNLESS– Purulent sputum + increased risk (age > 75 and fever, CHF,

insulin dependent DM, serious neurological disorder)• Abx for 3-5 days

Primary non-inferiority endpoint

Composite of adverse outcomes within 30 days of ED admission of:

• Death

• ICU admission

• Persistence or development of PNA

• Disease specific complications (abscess, empyema, ARDS)

• Recurrence of LRTI in need of antibiotics

Secondary superiority endpoints

• Duration of IV or PO abx

• Adverse effects of abx

• LOS

Assessment of outcomes

• Outcomes during the hospital stay assessed by unblinded physicians

• At 30 days, outcomes assessed by blinded medical students via telephone interviews

Patient flowchart

Retained 92.6%

Retained 94.4%

Patient demographics

Primary outcome

OR 0.76 (95% CI 0.57-1.01), favoring PCT group

Kaplan Meier Curves for Primary outcome

Secondary outcomes

Validity

1. Randomized? Yes, concealed by website2. Were the groups similar at start of trial?

Yes3. Blinded? Pts were blinded. BUT outcomes

assessed during the hospitalization by unblinded physicians Introduces bias! (Detection bias of subjective outcomes, Hawthorne effect)

4. Adequate follow-up? Yes5. Large dropout? No. >90% of pts

randomized were assessed at 30 days6. Intention to treat analysis? Yes

Validity7. Was the noninferiority margin defined a

priori on the basis of statistical reasoning and clinical judgment? Yes. Based on previous intervention trials, authors assumed overall adverse outcome rate of 20% (in this trial overall adverse outcome of control group was 18.9%, so this was a good assumption). Inferiority was defined a priori as overall adverse outcome of >27.5%.

8. Was the noninferiority assessment adequately powered? Sample size of 1002 was calculated to give power of 90%. 1381 pts were randomized

Conclusions

This study showed that patients treated by a procalcitonin based algorithm did no worse than control patients with regard to the composite of adverse events

The PCT algorithm decreased antibiotic prescribing, duration of exposure to antibiotics and adverse reactions to antibiotics

Further thoughts

• Could we come to the same conclusion if we used a CRP guided algorithm?

• What if we ignored biomarkers altogether and just treated LRTI with 3-5 days of antibiotics instead of 5-10 days?

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