Multilevel latent variable models for global health-related quality of life assessment.
Quality of life (QOL) assessment is a key component of many clinical studies and frequently requires the use of single global summary measures that capture the overall balance of findings from a potentially wide-ranging assessment of QOL issues. We propose and evaluate an irregular multilevel latent variable model suitable for use as a global summary tool for health-related QOL assessments. The proposed model is a multiple indicator and multiple cause style of model with a two-level latent variable structure. We approach the modeling from a general multilevel modeling perspective, using a combination of random and nonrandom cluster types to accommodate the mixture of issues commonly evaluated in health-related QOL assessments--overall perceptions of QOL and health, along with specific psychological, physical, social, and functional issues. Using clinical trial data, we evaluate the merits and application of this approach in detail, both for mean global QOL and for change from baseline. We show that the proposed model generally performs well in comparing global patterns of treatment effect and provides more precise and reliable estimates than several common alternatives such as selecting from or averaging observed global item measures. A variety of computational methods could be used for estimation. We derived a closed-form expression for the marginal likelihood that can be used to obtain maximum likelihood parameter estimates when normality assumptions are reasonable. Our approach is useful for QOL evaluations aimed at pharmacoeconomic or individual clinical decision making and in obtaining summary QOL measures for use in quality-adjusted survival analyses.
Department of Statistics, Macquarie University, Sydney, NSW, Australia. annette.kifley@mq.edu.au
Annette
A
Kifley
Gillian Z
GZ
Heller
Ken J
KJ
Beath
David
D
Bulger
Jun
J
Ma
Val
V
Gebski
D000970:Antineoplastic Agents / Q000009:adverse effects / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000009:adverse effects / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy / Q000523:psychology; D000069287:Capecitabine; D003520:Cyclophosphamide / Q000009:adverse effects / Q000627:therapeutic use; D003841:Deoxycytidine / Q000009:adverse effects / Q000031:analogs & derivatives / Q000627:therapeutic use; D005260:Female; D005472:Fluorouracil / Q000009:adverse effects / Q000031:analogs & derivatives / Q000627:therapeutic use; D006801:Humans; D008727:Methotrexate / Q000009:adverse effects / Q000627:therapeutic use; D008960:Models, Psychological; D015233:Models, Statistical; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic / Q000523:psychology / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires
D000970:Antineoplastic Agents; D003841:Deoxycytidine; D000069287:Capecitabine; D003520:Cyclophosphamide; D005472:Fluorouracil; D008727:Methotrexate