METHODS: Using multivariate analysis of variance, each definition was related simultaneously to four dependent measures - the Kessler 6 score for measuring psychological distress, the number of health-related bed-disability days, the number of visits to a health professional, and the number of emergency room visits. Following the protocol of Serlin et al, the definition yielding the largest F score was considered the optimal definition.
RESULTS: The Miller and Loeb definition produced the largest F value (185.87), followed consecutively by several alternative definitions #5 (184.17), #10 (180.95), and #9 (179.5). A nearly identical ordering was found when looking at the mean F value generated from 100 random samples. We also examined the frequencies with which each alternative definition achieved the optimal F value over the 100 random samples. Only two definitions had achieved the optimal F value >5% of the time: the Miller and Loeb definition was optimal 46% of the time, while alternative definition #5 was optimal 41% of the time. Similar results were seen in subpopulations with back pain and joint pain.
CONCLUSIONS: Additional support was provided for the Miller and Loeb coding of pain persistence and bothersomeness to produce discrete categories of increasing pain severity. This two-question coding scheme may prove to be a viable option for assessing pain severity in clinical settings where clinician time and patient burden are limiting factors.