Therapy Meropenem (1.5 g/day) is as effective as imipenem/cilastatin (2 g/day) for the treatment of moderately severe intra-abdominal infections.
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Summary
Posted By:	Stephen Drage
E-Mail:	fiona_and_steve@bigpond.com
Posted Date:	15/08/03
Title:	Meropenem (1.5 g/day) is as effective as imipenem/cilastatin (2 g/day) for the treatment of moderately severe intra-abdominal infections.
Authors:	Zanetti G, Harbarth SJ, Trampuz A, Ganeo M, Mosimann F, Chautemps R, Morel P, Lew D, Zimmerli W, Lange J, Glauser M.
Reference:	Int J Antimicrob Agents. 1999 Feb;11(2):107-13.
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Abstract:	This multicentre, open-label, randomised trial compared meropenem (0.5 g/8 h) and imipenem/cilastatin (at the commonly used dosage of 0.5 g/6 h) in monotherapy in patients with moderately severe intra-abdominal infections (IAIs). In total, 161 patients were randomised (82 meropenem, 79 imipenem/cilastatin). The mean APACHE II scores in the two groups were 5.8 and 6.4, respectively. At the end of therapy, 65/71 (91.6%) evaluable meropenem recipients were clinically cured or improved, compared to 60/64 (93.8%) imipenem/cilastatin recipients. This difference and that in an intention-to-treat analysis (82.1 vs 86.1%, respectively), were not statistically significant. Both drugs were generally well tolerated. Thus, meropenem 0.5 g/8 h is as clinically effective and well tolerated as imipenem/cilastatin 0.5 g/6 h in moderately severe IAIs.
Are the Results Valid?
1. Was the assignment of patients to treatments randomized? ( Was allocation concealment maintained?)
	Yes, randomisation was by computer generated random numbers. Allocation concealment was acheived by sealed envelopes. It is not clear at what point of the disease patients were randomised. Inclusion criteria were vague, diagnostic criteria for intra-abdominal infection were not reported.
2. Were all patients who entered the trial properly accounted for and attributed at its conclusion?
2a. Was followup complete?
	26 patients were excluded after randomisation for various reasons. Little information was provided as to the fate of these patients. Of those who continued in the study all were accounted for at the end of therapy (the primary end point). There was significant loss to follow up at 2 weeks.
2b. Were patients analyzed in the groups to which they were randomized?
	An intention to treat analysis was not carried out due to the high number of exclusions post-randomization.
3. Were patients, health workers, and study personnel blind to treatment?
	No attempt was made to blind patients,staff or researchers.
4. Were the groups similar at the start of the trial?
	The groups appeared to have similar baseline characteristics but more patients in the imipenem/cilastatin group (34% v 24%)were in ICU.
5. Aside from the experimental intervention, were the groups treated equally?
	More patients in the imipenem /cilastatin group had surgery (72% v 54%). This difference was not statistically significant.
What are the Results?
1. How large was the treatment effect?
	The preceeding criticisms of the study methodology cast serious doubt on the validity of the results. There was a small improved treatment effect with imipenem (82.1% v 86.1%) in the patients that were included in the efficacy subgroup analysis.
2. How precise was the estimate of the treatment effect?
	As above. Confidence intervals were not quoted. The difference was not significant. The study was only powered to detect a 20% difference in efficacy, when a smaller difference may have been clinically relevant.
Will the Results Help Me In Caring For My Patients?
1. Can the results be applied to my patient care?
	No, aside from the methodological flaws above (high loss to follow-up/exclusion from analysis rate) the patient group were not critically ill with average APACHE scores of around 6.
2. Were all clinically important outcomes considered?
	The primary outcome measure was cure or improvement in signs and symptoms. How these outcomes were assessed was not reported. Outcomes were assesed at the end of therapy. How the decision to stop therapy was made was unclear.
3. Are the likely treatment benefits worth the potential harms and costs?
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