ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2019) 63 P732 | DOI: 10.1530/endoabs.63.P732

Assessing clinical meaningfulness of quality of life (qol) change in patients with Cushing's disease: calculation of minimal important difference estimates for the cushingqol using anchor and distribution-based approaches

Ying Wu1, Elaine Brohan2, Kate Sully2 & Ricardo Maamari1


1Novartis Pharmaceuticals Corporation, New Jersey, USA; 2Adelphi Values, Bollington, UK.


Purpose: Patients with Cushing’s disease (CD) experience a wide range of physical and psychosocial health impacts. This can have a profound effect on patient’s quality of life (QOL), impairing areas such as body image, personal relationships and work performance. The CushingQoL is a valid and reliable disease-specific patient-reported outcome (PRO). When using a PRO in an interventional context it is critical to understand whether reported change is clinically meaningful. This study aims to derive estimates of the minimal important difference (MID) for the CushingQoL.

Methods: Anchor-based methods explore the association between change on a PRO and a related variable that identifies patients with an important change in their condition (the anchor). An improvement in CushingQoL score >10.1 has previously been estimated as an initial threshold for a clinically meaningful change, based on a distribution based method (using 0.5 SD) for defining the MID. This study will use data from SOM230G2304 to calculated anchor and distribution-based MID estimates and compare these to available estimates. SOM230G2304 is a Pasireotide LAR, phase III, randomized, double-blind, multicenter, study evaluating the efficacy and safety of two Pasireotide LAR regimens in patients (≥18 years old) with CD (n=148).

Results: The appropriateness of potential anchor variables was investigated (moderate correlation (r>0.4<0.7) as criterion). The following anchors met this criterion: SF12v2 Physical components scale used for CushingQoL total and psychosocial issues, SF12v2 Mental components scale used for CushingQoL total and psychosocial issues. A triangulation approach was used to discuss the estimates provided by both this anchor-based approach and distribution-based approaches.

Conclusions: This is the first known evaluation using clinical trial data to determine anchor-based MID values for the CushingQoL. The implications of these MID values for research and clinical practice are discussed along with guidance on best practice for evaluating the clinical meaningfulness of change scores on PROs.

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