Responsiveness of the testing morbidities index in colonoscopy

Objectives: The Testing Morbidities Index (TMI) was developed to measure the effects of any diagnostic or screening procedure on health-related quality of life (HRQOL); it includes seven domains incorporating mental and physical aspects before, during, and after testing. To add to prior work on the validity of the TMI classification, responsiveness of a summated scale version was evaluated in 71 colonoscopy patients. Further data on construct validity were also obtained.

Methods: Patients enrolled in the study when scheduling colonoscopy days to weeks beforehand. The baseline survey included the EuroQol five-dimensional (EQ-5D) questionnaire with five levels in each attribute (EQ-5D-5L questionnaire) and its visual analogue scale (VAS) assessment (EQ-VAS), the Short Form 12 version 2 (SF-12v2) component summary scores and six-dimensional health state short-form (derived from the short-form 12v2 health survey [SF-6D] utilities), and an original construct-specific VAS (CS-VAS) for usual HRQOL using utility scale anchors. The TMI's highest possible summated score (all best levels) served as its baseline. Survey data were generally obtained by telephone interview. A postprocedure survey was given to patients after colonoscopy and interviews conducted as soon as possible after the day of the procedure. The postprocedure survey included the SF-12v2/SF-6D, EQ-5D questionnaire instruments, TMI items, and a CS-VAS incorporating the overall HRQOL effects of colonoscopy.

Results: Standardized response means showed greatest responsiveness by the TMI (-1.52) followed by the CS-VAS instruments (-0.42). The EQ-5D-5L questionnaire, the EQ-VAS, and the SF-12 component summaries were unresponsive, and the SF-6D was minimally responsive (-0.05). Correlation of the post-CS-VAS with the TMI was substantial (r = -0.52), suggesting TMI construct validity. Moderate to strong correlation of the baseline CS-VAS with standard indexes was observed (r = 0.54-0.81).

Conclusion: The TMI appears responsive and exhibits further evidence of construct validity.