The WHO analgesic ladder for cancer pain management. Stepping up the quality of its evaluation.

OBJECTIVE To perform a systematic review of studies evaluating the effectiveness of the World Health Organization (WHO) analgesic ladder as an intervention for cancer pain management. DATA SOURCES Systematic search of MEDLINE from 1982 to 1995, hand search of textbooks and meeting proceedings, reference lists, and direct contact with authors. STUDY SELECTION Studies of any methodological design were included if they evaluated patients with cancer pain treated according to the WHO analgesic ladder and if the studies provided enough information to estimate the proportion of patients who achieved adequate analgesia with the use of the ladder. The strength of the evidence provided by each study was assessed separately by both authors using current concepts. DATA EXTRACTION From the hard copy of each study report, the first author's name, publication year, study design, number of dropouts per study, and proportion of patients with adequate analgesia in each study were extracted. DATA SYNTHESIS Eight studies purporting to evaluate the effectiveness of the WHO ladder were included in the review. Meta-analysis was not performed because the studies were case series with no control groups. The studies had other limitation: none provided information on the conditions in which pain was assessed; two were retrospective; one had short follow-up periods; three had high withdrawal rates; and one had variable follow-up periods. Analgesia was adequate in 69% to 100% of patients analyzed in the studies. CONCLUSIONS The studies available provide valuable information on the course of cancer pain and its treatment. However, the evidence they provide is insufficient to estimate confidently the effectiveness of the WHO analgesic ladder for the management of cancer pain. Until results from carefully designed controlled trials are available, it would be inappropriate to judge the performance of clinicians, programs, and institutions or to design policies based on such evidence.