OPTIMAL SCORING STRATEGIES AND WEIGHTS FOR THE FORMALIN TEST IN RATS

The formalin test is a well-established model for assessing inflammato ry nociceptive processes and analgesic drug effects. Previous research established the validity of an ordinal relationship among three well- defined pain behavior categories used to compute a composite pain scor e (CPS). However, optimal weights bad not been validated. The present research used data from Coderre et al. (1993) and from Sufka and Roach (1996) to determine and validate optimal pain behavior category weigh ts. Based on multiple regression analyses and Pearson correlations, op timal weights of 1 and 2 are proposed for behavior categories 2 and 3, respectively; behavior category I is not scored. These results are co nsistent with the work of Abbott et al. (1995) and Coderre et al. (199 3) in that the ordinal relationship among category weights is preserve d, and extend previous work by establishing optimal category weights. (C) 1997 International Association for the Study of Pain.