title: Assessing the response to opioids in cancer patients: a methodological proposal and the results.
abstract: OBJECTIVE
  The efficacy of treatment with opioids in cancer pain is variable. To evaluate this variability, we (1) applied two parameters, changes in pain intensity (PI) and opioid daily doses (DDs), to distinguish different responses to opioids. The need to switch to another opioid was recorded. We then (2) evaluated the distribution of the responses depending on these parameters, alone and taken together, in cancer patients with pain.
  
  
  METHODS
  The cutoffs between positive and negative responses related to PI and DD were defined on the basis of the literature. For PI, responders were patients who obtained simultaneously a decrease of 30% or more and a final score ≤4 points (numerical rating scale 0 to 10). For DD changes, we applied the opioid escalation index percentage, a positive response corresponding to a dose increase ≤5%. These criteria were applied to 201 cancer patients treated with WHO step III "strong" opioids for 21 days. The results were mainly analyzed case by case.
  
  
  RESULTS
  Of the patients, 63.7% obtained a positive analgesic response and 80.1% a dose-related positive response. Combining the parameters, the response was double positive in 55.2% of cases, double negative in 11.4%, a good analgesic response with a large dose escalation in 8.5%, and no pain relief with a stable dose in 24.9%. Switches were made 21 times, 15 because of the lack of analgesia.
  
  
  CONCLUSIONS
  Different degrees of response to opioids were observed, PI and DD changes both contributing. Only over half the patients had a full positive response.
authors.affiliation: Pain and Palliative Care Research Unit, IRCCS - Institute for Pharmacological Research "Mario Negri", Via La Masa 19, 20156, Milan, Italy.
authors.forename: O
authors.initials: O
authors.lastname: Corli
authors.forename: A
authors.initials: A
authors.lastname: Roberto
authors.forename: M T
authors.initials: MT
authors.lastname: Greco
authors.forename: M
authors.initials: M
authors.lastname: Montanari
mesh_terms: D000368:Aged; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications* / Q000188:drug therapy; D010146:Pain / Q000175:diagnosis* / Q000188:drug therapy*; D059408:Pain Management / Q000379:methods; D010147:Pain Measurement / Q000379:methods*
chemical_list: D000701:Analgesics, Opioid