bNoninferiority trial design and analyses are commonly used to establish the effectiveness of a new antimicrobial drug for treatment of serious infections such as complicated urinary tract infection (cUTI). A systematic review and meta-analysis were conducted to estimate the treatment effects of three potential active comparator drugs for the design of a noninferiority trial. The systematic review identified no placebo trials of cUTI, four clinical trials of cUTI with uncomplicated urinary tract infection as a proxy for placebo, and nine trials with reports of treatment effect estimates for doripenem, levofloxacin, or imipenem-cilastatin. In the meta-analysis, the primary efficacy endpoint of interest was the microbiological eradication rate at the test-of-cure visit in the microbiological intent-to-treat population. The estimated eradication rates and corresponding 95% confidence intervals (CI) were 31.8% (26.5% to 37.2%) for placebo, 81% (77.7% to 84.2%) for doripenem, 79% (75.9% to 82.2%) for levofloxacin, and 80.5% (71.9% to 89.1%) for imipenem-cilastatin. The treatment effect estimates were 40.5% for doripenem, 38.7% for levofloxacin, 34.7% for imipenem-cilastatin, and 40.8% overall. These treatment effect estimates can be used to inform the design and analysis of future noninferiority trials in cUTI study populations.
Complicated urinary tract infections (cUTI) occur in persons with structural or functional abnormalities of the urinary tract and in hospitalized patients with significant medical or surgical comorbidities (1, 2). These infections are a major cause of hospital admission, morbidity, mortality, and excess health care costs (3-6). National and international treatment guidance for urinary tract infections includes recommendations for targeted and empirical treatment of the major causative pathogens, including Escherichia coli, Klebsiella pneumoniae, and non-Enterobacteriaceae organisms such as Pseudomonas aeruginosa (7-9).Of notable concern for the clinical care of patients with cUTI and other serious infections is effective antimicrobial treatment amid the emergence and spread of drug-resistant pathogens (10, 11). To demonstrate efficacy of a new or test antimicrobial agent for the treatment of adult subjects with cUTI, randomized parallel-group noninferiority phase 3 trials have traditionally been used to meet regulatory requirements for approval of the test drug (12). An active-comparator, noninferiority study design is generally used in cUTI trials given the ethical implications of placebo treatment (13,14). In order to conduct a noninferiority trial, an estimate of the treatment effect of the planned antimicrobial comparator must be obtained from historical data (12). Once an estimate of the treatment effect of the antimicrobial comparator is determined, the largest clinically acceptable difference of the test drug compared to the comparator must be decided. This decision is critical to the design, analysis, and interpretation of a noninferiority trial.We conducted a systematic review and me...