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