Measuring outcomes of vision rehabilitation with the Veterans Affairs Low Vision Visual Functioning Questionnaire.

PURPOSE: To evaluate the sensitivity to change, in patients who undergo vision rehabilitation, of the Veteran Affairs (VA) Low Vision Visual Functioning Questionnaire (LV VFQ-48), which was designed to measure the difficulty visually impaired persons have in performing daily activities and to evaluate vision rehabilitation outcomes. METHODS: Before and after rehabilitation, the VA LV VFQ-48 was administered by telephone interview to subjects from five sites in the VA and private sector. Visual acuity of these subjects ranged from near normal to total blindness. RESULTS: The VA LV VFQ exhibited significant differential item functioning (DIF) for 7 of 48 items (two mobility tasks, four reading tasks, and one distance-vision task). However, the DIF was small relative to baseline changes in item difficulty for all items. Therefore, the data were reanalyzed with the constraint that item difficulties do not change with rehabilitation, which assigns all changes to the person measure. Subjects in the inpatient Blind Rehabilitation Center (BRC) program showed the largest changes in person measures after vision rehabilitation (effect size = 1.9; t-test P < 0.0001). The subjects in the outpatient programs exhibited smaller changes in person measures after rehabilitation (effect size = 0.29; t-test P < 0.01). There was no significant change in person measures for the control group (test-retest before rehabilitation). CONCLUSIONS: In addition to being a valid and reliable measure of visual ability, the VA LV VFQ-48 is a sensitive measure of changes that occur in visual ability as a result of vision rehabilitation. Patients' self-reports of the difficulty they experience performing daily activities measured with this instrument can be used to compute a single number, the person measure that can serve as an outcome measure in clinical studies. The VA LV VFQ-48 can be used to compare programs that offer different levels of intervention and serve patients across the continuum of vision loss.

Psychometric properties of the Veterans Affairs Low-Vision Visual Functioning Questionnaire.

PURPOSE: To describe psychometric properties of a self-report questionnaire, the Veterans Affairs (VA) Low-Vision Visual Functioning Questionnaire (LV VFQ-48), which was designed to measure the difficulty visually impaired persons have performing daily activities and to evaluate low-vision outcomes. METHODS: The VA LV VFQ-48 was administered by telephone interview to subjects with visual acuity ranging from near normal to total blindness at five sites in the VA and private sector. Rasch analysis with the Andrich rating scale model was applied to difficulty ratings from 367 subjects, to evaluate measurement properties of the instrument. RESULTS: High intercenter correlations for item measure estimates (intraclass correlation coefficient [ICC]=0.97) justified pooling the data from these sites. The person measure fit statistics (mean square residuals) confirm that the data fit the assumptions of the model. The item measure fit statistics indicate that responses to 19% of the items were confounded by factors other than visual ability. The separation reliabilities for pooled data (0.94 for persons and 0.98 for items) demonstrate that the estimated measures discriminate persons and items well along the visual ability dimension. ICCs for test-retest data (0.98 for items and 0.84 for persons) confirm temporal stability. Subjects used the rating categories in the same way at all five centers. Ratings of slight and moderate difficulty were used interchangeably, suggesting that the instrument could be modified to a 4-point scale including not difficult, slightly/moderately difficult, extremely difficult, and impossible. Fifty additional subjects were administered the questionnaire with a 4-point scale to confirm that the scale was used in the same way when there were four rather than five difficulty ratings. CONCLUSIONS: The VA LV VFQ-48 is valid and reliable and has the range and precision necessary to measure visual ability of low-vision patients with moderate to severe vision loss across diverse clinical settings.

Economic evaluation of blind rehabilitation for veterans with macular diseases in the Department of Veterans Affairs.

PURPOSE: The Department of Veterans Affairs (VA) Low Vision Intervention Trial (LOVIT) developed an outpatient low-vision programme for patients with macular diseases providing low-vision rehabilitation comparable to VA inpatient blind rehabilitation centres (BRCs). This programme targets veterans who do not need or chose not to participate in a comprehensive inpatient blind rehabilitation programme. We examined costs and consequences using veterans in LOVIT and comparable veterans in an inpatient BRC. METHODS: We compared costs and consequences between treatment patients who participated in LOVIT, a two-site randomized clinical trial, and a sample of comparable patients who received treatment at a VA inpatient BRC. We measured consequences as the change in functional visual ability from baseline to follow-up (LOVIT: 4 months after randomization; BRC: 3 months after discharge) using the VA Low Vision Visual Functioning Questionnaire (VA LV VFQ-48). RESULTS: There were 55 LOVIT and 121 BRC patients for our analyses. Average costs were $38,627.3 higher for BRC patients ($5,054.4 +/- $404.7 SD for LOVIT vs. $43,681.7 +/- $8,853.6 SD for BRC, p < 0.0001). Thus, the BRC cost $38,627.3 per patient more than the LOVIT programme (95% CI: $17,414 to $273,482). There was a greater improvement in overall visual ability, mobility, and visual motor skill scores for BRC patients; however, there was no significant difference in improvement in reading ability or visual information processing scores. CONCLUSIONS: As VA increases outpatient blind rehabilitation services, LOVIT provides a model for expanding outpatient low-vision rehabilitation services for veterans at substantially lower costs than current inpatient BRC services.

Short- and long-term effects of an intensive inpatient vision rehabilitation program.

OBJECTIVE: To assess the effects of a visual rehabilitation program on visually impaired subjects' visual ability and ability to perform activities. DESIGN: Prospective observational study. SETTING: Telephone interviews of respondents in their homes the week before admission to the rehabilitation center and 3 months and 1 year after discharge from the rehabilitation center. PARTICIPANTS: A total of 178 consecutive patients from the Hines Blind Rehabilitation Center participated in development of the 48-item Veterans Affairs Low Vision Visual Functioning Questionnaire (VA LV VFQ-48). Data were analyzed for 95 who participated in all 3 administrations of the questionnaire. INTERVENTION: Comprehensive blind rehabilitation program (mean hospital admission, 40 d). MAIN OUTCOME MEASURE: The self-report ratings of patients' difficulty performing 48 activities on the VA LV VFQ-48. RESULTS: The increase in visual ability +/- standard deviation of .981+/-.482 logits (equivalent to an 8-line improvement in visual acuity on an Early Treatment of Diabetic Retinopathy Study chart) at 3 months postrehabilitation decreased to .682+/-.485 logits (equivalent to a loss of 2.5 lines of visual acuity on the same chart) 1 year postrehabilitation. The effect sizes measured at 3 months (2.035) and 1 year (1.495) indicate large treatment effects corresponding to statistically significant differences for the increase in visual ability at 3 months and 1 year postrehabilitation (paired 2-tailed t tests, P<.001) relative to pretreatment measures. The difference in visual abilities measured at 3 months and 1 year posttreatment also is statistically significant (P<.001). CONCLUSIONS: Treatment effects decreased over the 12-month follow-up period. However, the group of patients whose data were analyzed was still statistically and clinically significantly better at their 1-year follow-up than before beginning treatment.

The Veterans Affairs Low Vision Intervention Trial (LOVIT): design and methodology.

BACKGROUND: Visual impairment is a major public health problem. Vision rehabilitation programs have the potential to restore independence and improve quality of life for persons with permanent vision loss, and few have been evaluated in randomized controlled trials. PURPOSE: The Veterans Affairs (VA) Low Vision Intervention Trial is a multicenter randomized clinical trial to evaluate the effectiveness of a new outpatient low vision rehabilitation program. METHODS: 126 patients with moderate and severe vision loss due to macular diseases are randomized to low vision treatment in an outpatient setting or a usual care control group at two VA facilities in Hines, Illinois, and Salisbury, North Carolina. The primary outcome is the change in visual reading ability from baseline to four months measured with the Veterans Affairs Low Vision Visual Functioning Questionnaire-48 (VA LV VFQ-48). Secondary outcomes compare the mean change in visual ability measured with the VA LV VFQ-48 (overall ability, mobility, visual information processing, visual motor skills) for the treatment and control groups. Costs and cost effectiveness of outpatient treatment are evaluated. RESULTS: The low vision rehabilitation setting, use of a waiting list control group to address ethical issues, development of the treatment protocol, development of a vision function questionnaire for patients to self-report the difficulty they experience performing daily activities, and the use of Rasch analysis to develop and estimate this outcome measure are described. LIMITATIONS: If the new low vision rehabilitation program is proven effective, studies will be needed to determine which of the multiple aspects of the intervention are necessary and sufficient. CONCLUSIONS: The challenges of conducting clinical trials in a rehabilitation setting and use of a waiting list (deferred treatment) control group extend beyond LOVIT. The design and methods of LOVIT may be applicable to other trials of rehabilitation services and to outcomes for which reliable and valid measurement tools must be developed.