813. Impact of Different Methods of Lesion Size Measurement on the Clinical Outcome in Acute Bacterial Skin and Skin Structure (ABSSSI ) Clinical Trials
Session: Poster Abstract Session: Bone and Joint
Friday, October 4, 2013
Room: The Moscone Center: Poster Hall C
Posters
  • Impact of Different Methods of Lesion Size Measurement on Outcomes in Acute Bacterial Skin and Skin Structure Infection (ABSSSI) Clinical Trials (Prokocimer et al) IDWeek 2013.pdf (451.5 kB)
  • Background: Outcomes in registrational clinical trials must be well-defined and reliable. The primary endpoint in ABSSSI clinical trials is based upon measurement of changes in the size of skin lesions. An open-label study of oral tedizolid phosphate (TZP) 200 mg QD for 6 days for the treatment of major cutaneous abscess or cellulitis/erysipelas in 200 adult subjects was conducted to assess whether different approaches to lesion size measurement affect the clinical response in ABSSSI trials.

    Methods: Two methods of measuring lesion area were compared: 1) inter-observer variability in lesion measurements by 2 different observers, and 2) impact of different definitions of lesion size as defined by erythema alone versus combining erythema, edema, and/or induration (erythema+) on outcome rates. Lesion length (head-to-toe orientation) and width (perpendicular to the length axis) were measured with a flexible plastic ruler at baseline and 48-72 hour visits. Responses to therapy defined as a reduction in lesion size ≥ 20% (G.H. Talbot, 2012) between the baseline and 48-72 hour visits were calculated for the 2 observers and also with the 2 lesion area definitions.

    Results: Response rates to therapy between the baseline and 48-72 hour visits were similar whether lesion areas were measured by 2 observers and whether lesion area was defined by erythema alone or erythema+ are presented in the table below.

    Conclusion: Different methods of lesion area measurement with a plastic ruler do not appear to affect clinical response rates as defined by a ≥ 20% reduction in lesion size. Clinical response rates were consistent whether lesions were assessed by 2 different observers or with 2 different definitions of lesion area, supporting the adequacy of using a simple plastic ruler to determine response to therapy in ABSSSI clinical trials. This evidence demonstrates the validity of skin lesion measurements in ABSSSI clinical trials.
    Lesion Definition Observation No. 1 Observation No. 2
    Erythema 81.0 80.5
    Erythema, Edema, and/or Induration 79.5 79.5

    Philippe Prokocimer, MD1, Edward Fang, MD1, Carisa De Anda, PharmD2, Cara Casseday1, John Powers, MD, FIDSA3 and Anita Das, PhD4, (1)Trius Therapeutics, Inc, San Diego, CA, (2)Trius Therapeutics, San Diego, CA, (3)Medicine, George Washington University School of Medicine, Bethesda, MD, (4)Axistat Inc, San Francisco, CA

    Disclosures:

    P. Prokocimer, None

    E. Fang, None

    C. De Anda, None

    C. Casseday, None

    J. Powers, None

    A. Das, None

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