Placebo-Controlled Trial of Antibiotic Therapy in Adults With Suspect Lower Respiratory Tract Infection (LRTI) and a Procalcitonin Level

This is a randomized, double-blinded, placebo-controlled, non-inferiority multicenter clinical trial of azithromycin vs. placebo in adults presenting as outpatients with suspect Lower Respiratory Tract Infection (LRTI) and a Procalcitonin (PCT) level of \< / = 0.25 ng/mL, as a strategy for reducing antibiotic prescriptions. The study is designed to compare the efficacy of azithromycin versus placebo on Day 5 (i.e., after 4 days of treatment) in subjects with suspect LRTI and PCT levels of \< / = 0.25 ng/mL at enrollment using a non-inferiority approach. The study will recruit potential subjects 18 years of age or older who are suspected to have LRTI. The enrollment cap will be 840 participants, for the goal of approximately 674 randomized participants who will be randomized 1:1 to receive oral azithromycin or placebo for five days. Randomized subjects will have efficacy measured from the time of the first dose of study drug (Day 1) through approximately Day 28. The Primary Objective is to compare the efficacy of azithromycin versus placebo on Day 5 (i.e., after 4 days of treatment) in subjects with suspect LRTI and PCT levels of \< / = 0.25 ng/mL at enrollment using a non-inferiority approach.

This is a randomized, double-blinded, placebo-controlled, non-inferiority multicenter clinical trial of azithromycin vs. placebo in adults presenting as outpatients with suspect Lower Respiratory Tract Infection (LRTI) and a Procalcitonin (PCT) level of \< / = 0.25 ng/mL, as a strategy for reducing antibiotic prescriptions. The study is designed to compare the efficacy of azithromycin versus placebo on Day 5 (i.e., after 4 days of treatment) in subjects with suspect LRTI and PCT levels of \< / = 0.25 ng/mL at enrollment using a non-inferiority approach. The study will recruit potential subjects 18 years of age or older who are suspected to have LRTI. The enrollment cap will be 840 participants, for the goal of approximately 674 randomized participants who will be randomized 1:1 to receive oral azithromycin or placebo for five days. Randomized subjects will have efficacy measured from the time of the first dose of study drug (Day 1) through approximately Day 28. The primary objective is to compare the efficacy of azithromycin versus placebo on Day 5 (i.e., after 4 days of treatment) in subjects with suspect LRTI and PCT levels of \< / = 0.25 ng/mL at enrollment using a non-inferiority approach. The secondary objectives are to compare:1) groups receiving azithromycin versus placebo with regard to all antibiotic use by Days 11 and 28; 2) groups receiving azithromycin versus placebo with regard to return visits to a physician's office or urgent care by Days 11 and 28; 3) groups receiving azithromycin versus placebo with regard to emergency department visits by Days 11 and 28; 4) groups receiving azithromycin versus placebo with regard to hospitalization by Days 11 and 28 if not hospitalized at the enrollment and randomization visit; 5) groups receiving azithromycin versus placebo with regard to improvement in presenting symptoms by Days 11 and 28; 6) the efficacy of azithromycin versus placebo on Day 11 in subjects with suspect LRTI and PCT levels of \< / = 0.25 ng/mL at enrollment using a non-inferiority approach; 7) the efficacy of azithromycin versus placebo on Day 28 in subjects with suspect LRTI and PCT levels of \< / = 0.25 ng/mL at enrollment using a non-inferiority approach; 8) the efficacy of azithromycin versus placebo in subjects with suspected LRTI and PCT levels of \< / = 0.25 ng/mL at Day 5 using a superiority approach, employing the "Response Adjusted for Days of Antibiotic Risk (RADAR)" methodology; 9) groups receiving azithromycin versus placebo in regard to solicited events by Day 5; 10) groups receiving azithromycin versus placebo in regard to hospitalization or visits to an Emergency Department (ED), outpatient clinic, or urgent care center for worsening or persistent LRTI after randomization by Day 5; 11) groups receiving azithromycin versus placebo in regard to improvement in vital sign abnormalities or symptoms present at enrollment, on Day 5; 12) groups receiving azithromycin versus placebo in regard to new vital sign abnormalities or symptoms on Day 5, or deterioration in symptoms relative to the enrollment visit on Day 5.

Eligibility Criteria:
Inclusion Criteria:

1. Clinician suspected Lower Respiratory Tract Infection (LRTI)\* based on the presence of at least two qualifying symptoms\*\* OR one qualifying symptom and at least one qualifying vital sign\*\*\*.

   \*LRTI will include acute bronchitis, tracheitis, tracheobronchitis, asthma exacerbation, and acute exacerbation of Chronic obstructive pulmonary disease (COPD) but does not include known pneumonia.

   \*\*New cough, worsening of chronic cough, new sputum production, increased volume or purulence of chronic sputum production, chest pain, and difficulty breathing.

   \*\*\*Fever (Provider or patient-measured temperature \> / = 37.8 degrees Celsius (100.0 degrees Fahrenheit) or patient-reported feverishness), tachycardia of \> / = 90 beats/minute, tachypnea of \> 20 breaths/minute.
2. Males and females age \> / = 18 years old.
3. Presentation \> / = 24 hours and \< / = 28 days after the onset of at least one qualifying symptom related to the acute episode of illness.
4. Ability to understand study procedures and willing and able to comply with all required procedures and visits for the entire length of study.
5. Provide written informed consent before initiation of any study procedures.

Exclusion Criteria:

1. Hospitalized prior to screening and enrollment. Subjects enrolled in clinic or Emergency Department (ED) setting and then hospitalized during the same clinical encounter may be included.
2. Chronic pulmonary conditions at the investigator's discretion\*.

   \*Such as:
   * Noninvasive ventilation use for any indication other than obstructive sleep apnea
   * Long-term invasive mechanical ventilation for any indication
   * Known diagnosis of cystic fibrosis or chronic bronchiectasis.
3. Receipt of an investigational product within 30 days prior to Day 1 or plans to potentially start any investigational product within 30 days after the subject's anticipated study completion.
4. Current enrollment in another clinical trial of an investigational agent.
5. Known or suspected infection at any other anatomic site requiring antibacterial therapy.
6. Immunosuppression\*

   \*Includes:
   * Human Immunodeficiency Virus (HIV) infection with CD4 \< 200 based on last known measurement or patient-reported value
   * History of hematologic malignancies
   * Receipt of chemotherapy within the previous 6 months or anticipated receipt of chemotherapy during the study period (1 month)
   * Known to have an absolute neutrophil count of \< 500 cells/mL or an expectation of an absolute neutrophil count of \< 500 cells/mL during course of the study
   * Current systemic corticosteroid use (equivalent of 20mg prednisone per day for \> / = 2 weeks within the last month)
   * Systemic non-steroid immunosuppressive or biologic therapy for transplant, rheumatologic conditions, or other conditions within the last month. Biologics used specifically for control of moderate to severe asthma, including anti-IgE monoclonal antibody therapy (Xolair) or IL-5 monoclonal antibodies (Mepolizumab and Reslizumab) are allowed
7. Contraindication to the use of azithromycin including history of allergy or intolerance to azithromycin or known prolonged QTc interval (\> 500 msec).
8. Any condition that in the judgment of the referring provider or site investigator precludes participation because it could affect subject safety or ability of subject to participate in this trial.
9. Prior use of azithromycin in the past two weeks.
10. Use of any systemic antibiotic in the previous 24 hours.
11. Previous randomization in this trial.