Total score or subscales in scoring the acromegaly quality of life questionnaire: using novel confirmatory methods to compare scoring options

Context: Impaired quality of life (QoL) is common in patients after long-term remission of acromegaly. The acromegaly QoL (AcroQoL) is a disease-specific QoL questionnaire for patients diagnosed with acromegaly. The summed total score is the most frequently used scoring method of the AcroQoL. However, the total score does not capture all of the aspects of QoL that are outlined by the World Health Organization (WHO). Objective: The aim of the present study was to use novel and sophisticated confirmatory methods to identify the optimal number of subscales for the AcroQoL. Design and patients: Patients in remission from acromegaly were recruited from the Leiden University Medical Center and were asked to complete the AcroQoL (Dutch version) questionnaire (n=72). Results: The three-subscale version of the AcroQoL consisted of subscales reflecting Physical Complaints, Appearance Issues, and Personal Relations Issues related to QoL. Model fit indices (i.e., comparative fit index and root mean square error of approximation) indicated that the three-subscale version represented the data better than the total score and two-subscale models did. A chi(2) difference test indicated that the three-subscale model was a significantly better fit than the total score and two-subscale models were (P<0.05). Conclusion: Model fit and comparison statistics indicate that the three-subscale model is a better scoring method than the total score and two-subscale versions of the AcroQoL are. The three-subscale version also better reflected the WHO's recommendation of using a multidimensional measure of QoL than the total score and two-subscale methods did. Therefore, it is recommended that values from the three-subscales of the AcroQoL be reported in future research.