An instrument assessing satisfaction with iron chelation therapy: Psychometric testing from an open-label clinical trial.
BACKGROUND
The Satisfaction with Iron Chelation Therapy (SICT) instrument was developed based on a literature review, in-depth patient and clinician interviews, and cognitive debriefing interviews. An, open-label, single arm, multicenter trial evaluating the efficacy and safety of deferasirox in patients diagnosed with transfusion-dependent iron overload, provided an opportunity to assess the psychometric measurement properties of the instrument.


METHODS
Psychometric analyses were performed using data at baseline from 273 patients with a range of transfusion-dependent iron overload conditions who were participating in a multinational study. Responsiveness was further evaluated for all patients who also had subsequent satisfaction domain scores collected at week 4.


RESULTS
Baseline SICT domain scores had acceptable floor and ceiling effects and internal consistency reliability (Cronbach's alpha: 0.75-0.85). Item discriminant and item convergent validity were both excellent although one item in each analysis did not meet the specified criterion. Small to moderate correlations were observed between SICT and Short Form 36 Health Survey (SF-36) domain scores. Patients with the highest levels of serum ferritin at baseline (>3100 ng/mL) were the least satisfied about the Perceived Effectiveness of ICT and vice versa. Satisfaction improved in all patients, although there were no clear differences observed between groups of patients defined according to changes in serum ferritin levels from baseline to week 4 (stable, improved, or worsened).


CONCLUSIONS
The SICT domains are reliable and valid. Further testing using a more specific criterion (such as assessing patient global ratings of change in satisfaction domains that correspond to the SICT domains) could help to establish with greater confidence the responsiveness of the instrument.
Rofail
Diana
D
Mapi Values, Adelphi Mill, Bollington, Cheshire, SK10 5JB, UK, diana.rofail@mapivalues.com
Viala
Muriel
M
Gater
Adam
A
Abetz-Webb
Linda
L
Baladi
Jean-Francois
JF
Cappellini
Maria Domenica
MD
D000328:Adult; D005293:Ferritins / Q000097:blood; D006801:Humans; D007502:Iron Chelating Agents / Q000592:standards / Q000627:therapeutic use; D019190:Iron Overload / Q000097:blood / Q000209:etiology / Q000523:psychology* / Q000628:therapy; D008875:Middle Aged; D017060:Patient Satisfaction / Q000706:statistics & numerical data; D011594:Psychometrics; D012015:Reference Standards; D011795:Surveys and Questionnaires / Q000592:standards; D065227:Transfusion Reaction; D016896:Treatment Outcome; D055815:Young Adult
D007502:Iron Chelating Agents; D005293:Ferritins