CONCLUSIONS: These performance-based measures may be used reliably across a wider range of testing environments and elderly populations than has been reported.
Single or area-based measures may be inadequate.
Our demonstration of widespread, 'progressive' grey matter involvement over time suggests that cortically-based measures may be the most suitable in this regard.
Performance-based measures may be more useful in assessing younger subjects [ 8]; however recent reports indicate that further assessment are needed to determine which performance-based measures are best suited for this population [ 9].
Thus, road-based measures may be better predictors of transmission risk than just simple Euclidean distance, especially in areas where roads go around large geographical features such as hills, rivers and estuaries.
Previous comparative studies suggest that chart-review-based measures may be slightly more accurate than administrative data-based comorbidity measures in predicting objective outcomes such as mortality and length of hospital stay [ 6, 38, 41].
Furthermore, for older couples in the United Kingdom, area-based measures may be preferable because of changes in the meaning of individual measures of socioeconomic status with aging and the difficulty of measuring socioeconomic status meaningfully in older people, which has been well described (20).
For example, pharmacy based measures may provide more detailed information on active chronic conditions for which patients are actually receiving care and not only serious conditions that diagnostic based measures may identify.
Creatinine based measures may underestimate declines in GFR if tubular secretion remains intact, particularly when GFR is initially low.
Finally, given the fact the respiratory domain was not a significant predictor of EQ-5D utility, and the emphasis on respiratory symptoms in CF trials, the development of a disease specific preference based measure may also be worth further investigation.
