La Grow Steven J
School of Health Sciences, Massey University, Palmerston North, New Zealand.
Optom Vis Sci. 2007 Aug;84(8):785-8. doi: 10.1097/OPX.0b013e31812f5f24.
This study set out to determine the degree to which the composite score of the National Eye Institute 25-item Visual Function Questionnaire (VFQ-25) predicted perceived quality of life (PQoL) as measured by a single-item global measure of quality of life (QoL) and therefore, the extent to which the two were measuring the same construct.
Hierarchical multiple regression was used to determine the ability of VFQ-25 to predict PQoL, while controlling for other variables significantly correlated with PQoL. The latter were entered as independent variables in the first step of this analysis and VFQ-25 in the second. This model determines the degree to which VFQ-25 predicted PQoL when all other variables were controlled for.
Of the other variables assessed, only general health and group affiliation were found to be significantly correlated with PQoL. These variables, entered in step 1 of the analysis, explained 24.3% of the variance (adjusted r = 0.243) in PQoL. When VFQ-25 was entered in step 2, the model then explained 29.3% (adjusted r = 29.3) of the variance or an additional 5% when the effects of the other two variables were controlled for (r change = 0.050, p = 0.001). In other words, VFQ-25 only predicted 5% of the variance found in PQoL. Therefore, 95% of the variance was not explained by this measure.
It is clear from the results of this study that VFQ and PQoL were not measuring the same construct. It is also apparent that the single-item global measure of QoL did indeed ask participants to rate their PQoL. Thus, we may conclude that the measure of vision-related QoL used in this study did not measure PQoL. Further research is required to determine the extent to which this finding may apply to other measures of vision-related QoL.
本研究旨在确定美国国立眼科研究所25项视觉功能问卷（VFQ - 25）的综合得分在多大程度上能够预测通过单一项目总体生活质量（QoL）测量得出的感知生活质量（PQoL），进而确定两者在多大程度上测量的是同一结构。
采用分层多元回归来确定VFQ - 25预测PQoL的能力，同时控制与PQoL显著相关的其他变量。在该分析的第一步中，将后者作为自变量纳入，第二步纳入VFQ - 25。此模型确定在控制所有其他变量时VFQ - 25预测PQoL的程度。
在所评估的其他变量中，仅发现总体健康状况和群体归属与PQoL显著相关。在分析的第一步纳入这些变量后，它们解释了PQoL中24.3%的方差（调整后r = 0.243）。当在第二步纳入VFQ - 25时，该模型随后解释了29.3%的方差（调整后r = 29.3），即在控制其他两个变量的影响后额外增加了5%（r变化 = 0.050，p = 0.001）。换句话说，VFQ - 25仅预测了PQoL中5%的方差。因此，该测量方法未能解释95%的方差。
从本研究结果可以清楚地看出，VFQ和PQoL测量的不是同一结构。同样明显的是，单一项目总体生活质量测量确实要求参与者对其PQoL进行评分。因此，我们可以得出结论，本研究中使用的与视力相关的生活质量测量方法并未测量PQoL。需要进一步研究以确定这一发现可能适用于其他与视力相关的生活质量测量方法的程度。
