The specific aims of the proposed project are: to develop and validate a self-administered form of the QWB, referred to as the QWB-SA; to perform preference measurement studies in order to obtain a scoring system for the QWB-SA; and to develop a vision specific scoring system for the QWB-SA.
Aim 1 : Develop and validate QWB-SA.
Aim 1 involves several steps. First the investigators will expand on the current list of symptoms in the QWB. A draft of the QWB-SA (already developed) will be sent to 15 experts for review and comment. Next, a content analysis of the HRQL literature will be performed to determine the degree to which the QWB-SA adequately captures items included in existing measures. After further revisions of the QWB are complete, the QWB-SA will be pilot tested at the UCSD Multipurpose Arthritis Center, and with patients in Family Medicine Clinics. Next, the measure will be field tested in ongoing studies at UCSD and in clinical research centers. In addition, a stratified random sample of 10 percent (200) will be selected for further study. These 200 patients will complete the interviewer administered QWB and the SF-36, with appropriate counterbalancing and administration at two time points with about one-month separation. A qualitative analysis for assessing the accuracy of information developed in the surveys will be performed on the 200 patients' data, using the Internal Consistency Analysis method. Additional analyses of the full 2,000, and the subset of 200, will include: item analysis to assess missing data rates and frequency distributions for all items; comparisons of mean QWB and QWB-SA scores; correlation analyses of all components of the QWB, QWB-SA and SF-36 to determine which of the QWB's is most correlated with the SF-36; and subanalyses of the QWB-SA by demographic variables, including age, gender, and education. Profile scoring of the QWB will be performed using factor analyses, with expected clusters including: physical activity, social activity, self-care, mobility, pain, emotional functioning, and sensory functioning. Factor scores will be created by obtaining the sum of item responses and factor score coefficients separately for each dimension.
Aim 2 : Preference measurement study to obtain a scoring system for the QWB-SA. Five hundred patients from the primary care clinics at the UCSD will be recruited into this phase of the proposed research. They will be evenly divided by gender, all will be adults, and about 40 percent will be African American or Hispanic. All participants will rate complete case descriptions and components of different health states, using a 1-100 point scale. Analyses of the preference data will involve two phases: establishment of the interval scale property and the development of the model of judgment; and, estimation of value weights.
Aim 3 : Disease-specific versus general measure. In this phase of the study, the investigators propose to develop a vision specific scoring system for the QWB-SA. Two hundred fifty patients undergoing their first eye cataract extraction will be recruited into the study. Participants must be older than 35 years of age. Exclusion criteria include: inability to speak English; serious hearing impairment; cognitive impairment; patients undergoing simultaneous glaucoma, corneal or vitro-retinal procedures; patients with traumatic cataracts; and patients with visual impairment so severe that they cannot complete a self-administered form. In addition to the QWB-SA data, data will be collected on visual acuity and patients will complete the VF-14, a functional status measure designed specifically for visual problems. Also, a cataract symptom score scale and a brief medical co-morbidity scale will be administered to the patients. Psychometric methods will be used to evaluate items from the QWB-SA and the vision-specific measures in relation to visual acuity and a vision specific outcome measure.
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