To the Editor:—We thank Drs. Rubenstein and Kane and Dr. Johnson for their interest in and comments on our paper. Rubenstein and Kane decry the lack of an “appropriate” population in our study, but surely their a priori insistence on a restricted population for geriatric assessment units prejudges the issue without experimentation. It is not uniformity but heterogeneity that characterizes geriatric assessment units in the United States today.1 In fact, there is good reason to believe that early, balanced, and effective intervention in the acute illness of elderly patients coupled with attention to their multiple chronic illnesses and rehabilitation needs would in fact improve placement location upon discharge. The fact that our study did not show a measurable difference between the control and assessment unit groups may mean that the hypothesis is wrong or, equally possibly, that our information base for therapeutic decisions in geriatrics is inadequate. Our recent experience with dementia, congestive heart failure, and urinary tract infections suggests that the latter may in fact be the case. Even those who use selection criteria similar to the ones suggested in Rubeinstein and Kane's letter do not fare noticeably better than we in terms of placement location.2 Whether or not measurable benefit may accrue to relatively small subgroups of patients selected on the basis of other criteria, as we suggested in our conclusion, awaits documentation. Clearly this will be an important focus for continuing research. The historical prospective study design used by us is well established and validated.3-5 This study design, of course, precludes prospective randomization but, nevertheless, random assignment of a control group is possible. In fact our use of the terms “controlled random sampling” and “random sample” are precise, deliberately chosen, and need to be read in context. We acquired the medical records of all admissions to the geriatric assessment unit and identified 268 general medicine patients controlled for age and sex admitted during the same time interval. From this pool of 268 patients we selected, using a random number table, 62 study subjects. This sample of 62 patients indeed constitutes a true randomly selected sample from an appropriate universe. The phrase “approximated randomization” is found in the addendum to our article and is used by another author for an entirely different study. Dr. Johnson raises several issues. No attempt was made to stratify or sample according to functional status, mental status, and social support. Stratification on the basis of these three characteristics and including type of acute illness would require a very large n to detect a (say) 20 per cent reduction in nursing home placement with a strong power of the test. Assessment of functional status of acutely ill geriatric patients presents difficulties. Acute illnesses of any degree of severity reduce functional status to very low levels. The frequency of dementia was not different between the two groups we studied. Social supports were not addressed specifically but the unplanned, random admission procedure did not allow for a purposeful selection of patients with more favorable support systems to either unit. Post-assignment evaluation of the social support systems by one of the authors (LS), a social worker assigned to the geriatric unit who has extensive experience on the general medicine unit, suggests that there was no important difference in the level of social supports on admission. Except for complicating acute infections, chiefly pneumonia and urinary tract infections, the ten diagnostic categories did in fact represent the dominant diagnoses within the study populations and are not unrepresentative of the study groups. We certainly do not view geriatrics “as an area of health care characterized by chronological age and the presence or absence of an acute illness.” The age range was 75 to 99 years, the so-called old old, in which age-related alterations in physiology are well developed and the presence of multiple chronic diseases and functional impairments virtually universal. Examples of atypical presentations of disease were plentiful. That these patients did not represent a true population of hospitalized geriatric patients cannot be at issue. No one wishes more fervently than we that geriatric assessment units do in fact reduce nursing home placement in favor of placement of the patient back in his or her home, in the home of a relative, or in a sheltered housing development. The suggestion that our study will do irreparable harm to the concept of geriatric assessment units is, perhaps, tinged with hyperbole. We have great confidence in the wisdom and good sense of the readers of the Journal of the American Geriatrics Society. We view our study as an early and significant contribution, one of the many that will surely follow and ultimately define the role of a geriatric assessment unit in the practice of clinical geriatrics.