title: The impact of methodological approaches for presenting long-term clinical data on estimates of efficacy in psoriasis illustrated by three-year treatment data on infliximab.
abstract: BACKGROUND
  Psoriasis affects about 2-3% of the Caucasian population. Biologics such as infliximab, etanercept, adalimumab and ustekinumab are efficacious treatments of plaque-type psoriasis. Critical to monitoring drug efficacy and safety is availability of long-term data. Despite the chronic nature of psoriasis, to date limited long-term clinical data have been available, as challenges are inherent in conducting a long-term analysis. With increasing time, it is more likely that the number of patients discontinuing treatment will also increase, due to loss of efficacy, adverse events or loss to follow-up. Interpretation of these data becomes confounded when one must consider missing data. Several approaches to analysing long-term data exist, and each accounts for missing data differently.
  
  
  OBJECTIVE
  To demonstrate that the choice of a particular analysis method to account for missing data has great impact on the assessed response rate.
  
  
  METHODS
  We used data from an open-label study over 3 years of continuous treatment with infliximab in patients with plaque-type psoriasis. These data were analysed by three methods--last observation carried forward, observed values and non-responder imputation--to account for missing data.
  
  
  RESULTS
  The 3-year PASI 75 responses varied from 41 to 75%, depending on the method of analysis; this shows that the response rate can almost double when a more liberal analytical approach is used.
  
  
  CONCLUSIONS
  While it is clear that the need for long-term data on biologics in psoriasis is great, considering the analysis undertaken is important when designing long-term studies and interpreting the resulting data. When analysis methods such as observed values only or last observation carried forward are used, the results of the more conservative non-responder imputation should also be presented to give a fair overview of the long-term efficacy of a treatment for plaque-type psoriasis.
authors: Third Department of Dermatology, A. Sygros Hospital, Semitelou 6, Athens, Greece. marinapapoutsaki@hotmail.com
authors: M
authors: M
authors: Papoutsaki
authors: M
authors: M
authors: Talamonti
authors: A
authors: A
authors: Giunta
authors: A
authors: A
authors: Costanzo
authors: M
authors: M
authors: Ruzzetti
authors: M
authors: M
authors: Teoli
authors: S
authors: S
authors: Chimenti
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D003627:Data Interpretation, Statistical; D003879:Dermatologic Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D000069285:Infliximab; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: D000911:Antibodies, Monoclonal; D003879:Dermatologic Agents; D000069285:Infliximab