Testing a model of association between patient identified problems and responses to global measures of health in low back pain patients: a prospective study

BACKGROUND: Self-rated health status has been shown to be related to physical function. Therefore, changes in functional ability should be associated with changes in general health. However, functional needs may vary greatly between individuals. The purpose of this study was to propose and test a model of association between patient identified functional problems and responses to global measures of health in low back pain patients. METHODS: Participants in a low back pain clinical trial were followed up for 12 months. A series of analyses were undertaken using the Jonckheere-Terpstra test and chi-square for trends to determine the associations between two individualised items related to function, and measures of "overall improvement in condition", "general health status" and performance of "usual activities". RESULTS: Significant associations between responses to the five items were found. Performance of usual activities is significantly associated with ratings of general health status (p < 0.001) and overall condition of the back (p < 0.001). The extent to which the patient identified problems influence an individual's perception on multi-task performance is dependent upon the degree of difficulty and level of importance attached to these problems. CONCLUSION: The relationship between patient identified problems and responses to global measures of health is complex. The explanatory model proposed here may improve our understanding of these interactions. TRIAL REGISTRATION: ISRCTN 32765488