But what if you can't walk at all for whatever reason? Then how do you predict mortality? Remember your Instrumental Activities of Daily Living ? The formal IADLs are the ability to use the telephone, shopping, food preparation, housekeeping, laundry, mode of transportation, responsibility for own medications, and ability to handle finances. The authors abstracted from this definition and graded competence in doing light housework, doing heavy cleaning, washing & ironing clothers, cleaning & making bed, preparing a hot meal, climbing stairs, getting around outdoors, shopping, and attending to feet & toenails. Complete independence in an activity rated 1 point while relying completely upon someone else rated 4 points, for a total score ranging from 9 up to 36.
It turns out that poor ability in IADLs as demonstrated by a score >25 was associated w/increase risk of mortality (and thusly, a decrease rate of survival), even after taking other variables into account. Bottom line, if you can walk, faster gait is better than slower. But even if you can't walk, greater independence in IADLs is associated w/lower mortality and greater survival.