Using the Rasch model to validate and enhance the interpretation of the Functional Assessment of Cancer Therapy-Kidney Symptom Index--Disease-Related Symptoms scale.
Value Health
; 12(4): 580-6, 2009 Jun.
Article
em En
| MEDLINE
| ID: mdl-19900256
ABSTRACT
OBJECTIVES:
The Functional Assessment of Cancer Therapy-Kidney Symptom Index-Disease-Related Symptoms (FKSI-DRS) was developed to assess patients' kidney-cancer-related symptoms. The Rasch rating scale, a one-parameter logistic item response model, may enhance FKSI-DRS interpretation and validate its measurement properties.METHODS:
We applied the Rasch model to FKSI-DRS data from a randomized phase 3 trial in which first-line sunitinib therapy showed superiority to interferon-alfa in patients with metastatic renal cell carcinoma. Of 750 enrolled patients, 668 patients completed the questionnaire on cycle 1, day 28 and were evaluated in the current study. The nine FKSI-DRS items were analyzed to enhance interpretation of the summary score by using an item characteristic curve that related score to probability of reporting specific symptoms.RESULTS:
The Rasch model fitted the FKSI-DRS well 8 of 9 items had acceptable infit and outfit statistics (<1.5, >0.5); item difficulty spanned a wide range (-3.23 to 1.64 logits); and the five response categories performed adequately. The item characteristic curve offered enhanced interpretation of FKSI-DRS For example, an FKSI-DRS score of 27 (mean baseline score for total sample) indicated a 47% chance of reporting "no" to "lack of energy," although a two-point difference between sunitinib and interferon-alfa, averaged across all assessments (29 vs. 27), corresponded to sunitinib achieving a 28% increase (13% absolute difference) in the probability of reporting "no" to "lack of energy" (60% vs. 47%).CONCLUSIONS:
Data suggest that the FKSI-DRS is an adequate measure of symptom status in patients with metastatic renal cell carcinoma. The Rasch model supports its validation and enhances its interpretation.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Carcinoma de Células Renais
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Interpretação Estatística de Dados
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Neoplasias Renais
Tipo de estudo:
Clinical_trials
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Diagnostic_studies
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Etiology_studies
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Health_economic_evaluation
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Prognostic_studies
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Risk_factors_studies
Limite:
Female
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Humans
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Male
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Middle aged
Idioma:
En
Revista:
Value Health
Assunto da revista:
FARMACOLOGIA
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
Estados Unidos