The Tuebingen Cushing's disease quality of life inventory: development and normative data from 1784 healthy people
T. Psaras, J. Honegger & M. Milian
Objective: In part I of the study a health related quality of life (HRQoL) inventory for Cushings disease (CD), the Tuebingen Cushing-25 quality of life inventory (Tuebingen CD-25) was developed. In the second part, we assessed normative data from healthy controls (HC) with which the individual patients scores can be compared.
Methods: Sources for item generation consisted of technical literature, interviews with patients and the rating of neurosurgeons, endocrinologists and a neuropsychologist. A preliminary inventory with 64 items was handed out to 63 CD patients. Item reduction and scale generation followed the principles of Classical Test Theory. Validation was performed with the WHOQoL-BREF. For assessing normative data, the inventory was filled out by 1784 HC omitting the introductory sentence Because of my Cushings disease that was included in the CD group.
Results: The final version of the Tuebingen CD-25 contained 25 items, showed high reliability (Cronbachs α =0.93) and validity (r=−0.65) and includes the subdomains depression, sexual activity, environment, eating behavior, bodily restrictions and cognition. We found a non-linear correlation between the Tuebingen CD-25 scores and patients age, younger and middle-aged patients having inferior HRQoL than patients between 31 and 50 years and older than 61 years. Preoperative 24 h UFC levels correlated significantly with the subscale cognition and only marginally failed significance level for the subscale Eating Behavior, while preoperative cortisol and ACTH levels did not correlate with any scale. In 28.6% of our CD patients we found slight and in 41.3% severe impairment in the Total Score of the Tuebingen CD-25 compared to HC. Less than one-third of our patient sample presented with unimpaired HRQoL.
Conclusion: The Tuebingen CD-25 is a feasible instrument to assess HRQoL in CD in a clinical and investigative setting and provides normative data for all age groups and genders.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.