title: Crossover and noncrossover designs in four-point parallel line analgesic assays.
abstract: Fifty-nine analgesic investigations designed as four-point parallel line crossover assays were examined. Sum of pain intensity differences (SPID) and total pain relief (TOTPAR) were the subjective response measures. Separate analyses with four-point crossover data and first-dose data (noncrossover) allowed comparison within each study of these two approaches. The crossover analysis allows for removal of the subject component of variance, which in these studies was a substantial fraction of the error variance (0.49 for SPID; 0.56 for TOTPAR). For this type of study, 2.4 times as many subjects would have to be recruited in a noncrossover design to obtain precision equivalent to that of the crossover design. Thus efficiency considerations argue for the crossover design in cases in which a treatment carryover effect may be assumed to be negligible.
mesh_terms: D000700:Analgesics / Q000627:therapeutic use*; D000704:Analysis of Variance; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004341:Drug Evaluation / Q000379:methods*; D006801:Humans; D008954:Models, Biological; D009020:Morphine / Q000627:therapeutic use*; D010146:Pain / Q000188:drug therapy*
chemical_list: D000700:Analgesics; D009020:Morphine