Stephen J.LurieMD, PhD, Senior EditorIndividualAuthorPhil B.FontanarosaMD, Executive Deputy EditorIndividualAuthor
To the Editor: Dr Liao and colleagues1 addressed the important issue of compression of
morbidity by analyzing data from the 1986 and 1993 National Center for Health
Statistics National Mortality Followback Surveys, and found an overall improvement
in quality in the last year of life among persons aged 85 years and older.
Unfortunately, this work is flawed because of major methodological differences
in the 2 surveys. First, the questions used to estimate prevalence of impairments
in activities of daily living (ADLs) are strikingly different in the 2 surveys.
Questions in 1986 asked about help or use of special equipment to perform
ADLs, whereas those in 1993 asked whether the decedent had any difficulty
performing these tasks. These are very different concepts and may provoke
different responses, thus introducing bias into the results. For example,
persons using special equipment to walk or bathe may not be perceived as having
difficulty. A recent study shows that individuals respond very differently
to these 2 types of questions.2
Lentzner HR. Quality of Life at the End of Life. JAMA. 2000;284(12):1513-1515. doi:10.1001/jama.284.12.1512