Validity and Reliability of the SF-36 Administered to Caregivers of Patients with Alzheimer's Disease

CECILIA M. SERRANO, CRISTINA G. RANALLI, CAROL DILLON, DIEGO SARASOLA, GALENO ROJAS, LEONARDO C. BARTOLONI, FERNANDO E. TARAGANO, GERARDO MACHNICKI, RICARDO F. ALLEGRI,

Chicago

Congreso; Meeting American Academy of Neurology 2008; 2008

American Academy of Neurology

OBJECTIVE: To evaluate the reliability and validity of the Argentinean version of the SF-36, a generic HRQoL instrument, in caregivers of patients with Alzheimer´s disease (AD). BACKGROUND: Patients with dementia require the presence of caregivers due to cognitive or functional impairments. Caregiving is associated with impaired health status and may reduce health related quality of life (HRQoL). DESIGN/METHODS: Data were obtained from the Memory Clinic in Zubizarreta Hospital at Buenos Aires, Argentina, from a cross-sectional study. Primary caregivers were sequentially included if the patient cared for had a diagnosis of Alzheimer´s disease. Caregivers completed the SF-36, the Zarit questionnaire and the Neuropsychiatric Inventory (to assess patient behaviours). Patients were evaluated for dementia severity using the Clinical Dementia Rating (CDR) and for cognitive status (Mini Mental State Examination, MMSE). Internal consistency, construct and discriminative validity and factorial validity were assessed. RESULTS: Forty-eight caregiver-Alzheimer´s patient pairs were enrolled. Two-thirds of caregiver´s patients had age between 20 and 65 years and 85% were female. Patient´s age was evenly distributed between 58-75 years and 76-89 years, and gender was evenly distributed. 50% has a CDR rating of 2 or higher. The SF-36 demonstrated high internal consistency (Cronbachs alphas 0.72-0.92). Correlations between the SF-36 and the Zarit were moderate (range: -0.19 to -0.79, all p<0.01 expect for physical function). Significant correlations between the SF-36 and the CDR, MMSE and NPI were lower (range: -0.30 to -0.4, p<0.001) and concentrated in the mental health components of the SF-36. These results indicate good concurrent and discriminative validity. The SF-36 demonstrated good factorial validity, as the factor loadings were above 0.6 for all scales except role emotional, with good model fit using the Comparative Fit Index (CFI) (0.93) and Non-Normed Fit Index (NNFI) (0.90) indexes but inadequate fit with the Satorra-Bentler Chi-square (p=0.03). CONCLUSIONS/RELEVANCE: The Argentinean version of the SF-36 demonstrated adequate reliability and concurrent, discriminative and factorial validity. It is reliable and valid for use in caregivers of patients with AD.