Minimum clinically significant VAS differences for simultaneous (paired) interval serial pain assessments.

We conducted two studies to determine whether the minimum clinically significant difference in the visual analog scale (VAS) for nearly simultaneous and brief-interval serial assessments of pain is less than that for pain assessment at 20- to 30-minute intervals, using a 10-cm VAS. The first study was a blinded, randomized, placebo-controlled paired trial comparing the pain of intravenous cannulation in both hands (20-minute application of a eutectic mixture of local anesthetics v placebo) of study subjects. The second study was a non-blinded, randomized, paired trial of different treatments for jellyfish stings. In the first study, 37 of 40 subjects indicated that one hand experienced more pain than the other. Eleven of these 37 subjects (30%) indicated differences in VAS values of 1.0 cm or less, with a minimum value of 0.5 cm. In the second study, for all the VAS-based pain comparisons, VAS differences of

A randomized paired comparison trial of cutaneous treatments for acute jellyfish (Carybdea alata) stings.

The objective of the study was to compare cutaneous treatments (heat, papain and vinegar) for acute jellyfish (Carybdea alata) stings. Healthy adult volunteer subjects received a single-tentacle jellyfish sting on each forearm. One forearm was treated with hot-water immersion (40-41 degrees C). This was compared with the other forearm, which was randomized to a comparison treatment of papain meat tenderizer or vinegar. Pain was measured at 0, 2, 4, 6, 8, 10, 15, and 20 minutes using a 10-cm visual analog scale (VAS). For 25 subject runs, the average VAS scores at t = 0 were 3.6 cm (hot water) and 3.7 cm (comparison treatment). At t = 4 minutes (2 minutes after treatment had started), the differences between hot-water and comparison group VAS scores were 2.1 cm versus 3.2 cm, respectively. The mean difference between hot-water and comparison treatments was 1.1 cm (95% confidence interval, 0.6 to 1.6). At t = 20 minutes (the end of the study period), the differences between hot-water and comparison group VAS scores were 0.2 cm versus 1.8 cm, respectively. The mean difference between hot-water and comparison treatments was 1.6 cm (95% confidence interval, 0.9 to 2.3). This study suggests that the most efficacious initial treatment for C alata jellyfish envenomation is hot-water immersion to the afflicted site.