Functional and Biomedical Components in the Measures of Disease Severity in Older People

To the Editor: We have read with interest the paper by Parmelee et al., “Validation of the Cumulative Illness Rating Scale in a Geriatric Residential Population,” recently published on the journal.1 The authors conclude that the CIRS appears to be a valid indicator because it distinguishes health status from functional disability, assuming that these conditions are not interchangeable. On the contrary, our impression is that CIRS gives too much emphasis to function, in this way disregarding the assumption that clinical problems have effects on general health which are, at least partially, independent from disability. We propose a different methodology, which is less linked to functional parameters while at the same time is able to capture the effects of disease severity on general health. We report here data obtained utilizing the physiological dimension of clinical problems measured by Greenfield's Index of Disease Severity-IDS, in which illness severity is scored independently by its impact on function.2 This index assigns a score (0–4) to absence of disease (0): asymptomatic disease (1), symptomatic disease controlled by therapy (2), symptomatic disease uncontrolled by therapy (3), life-threatening disease or the greatest severity achievable by the disease (4). In the definition of our Burden of Disease (BOD) index, based on the average of the 15 items, we considered the following diseases: heart diseases (ischemic and organic), primary arrhythmias, nonischemic congestive heart diseases, hypertension, peripheral vascular diseases, chronic lung diseases, gastrointestinal diseases, hepatic diseases, chronic kidney diseases, muscoloskeletal diseases, stroke, Parkinson's disease, anemia, diabetes mellitus, and tumors. Psychiatric and behavioral diseases are considered separately. We assessed the 357 older patients (256 females) admitted consecutively to our Geriatric Ward during the period August 15, 1993 to December 1994, on demographic, functional and clinical variables. Means (SD) were age (years = 78.9 (7.3); Mini-Mental State Examination = 21.7 (6.3); Geriatric Depression Scale = 13.7 (6.9); BADL (functions lost) = 2.6 (1.9); IADL (functions lost) = 4.8 (2.6); Tinetti scale = 15.9 (9.2); PPT = 12.0 (6.4); diseases (n) = 4.9 (1.7); drugs (n) = 5.1 (1.8). Means and standard deviations for each clinical problem, the BOD index value, and percent reporting moderate (IDS = 2) or greater impairment of IDS items are reported in the table. As recommended by Parmelee et al., we correlated the results with functional and clinical laboratory data to support the validity of the BOD index. The BOD index seems to be a reliable instrument to detect the correlation between the burden of diseases, function, and parameters of biomedical relevance. In particular, Pearson's r for the BOD index and ADL, IADL, Tinetti scale, and Physical Performance Test is, respectively, 0.24 (P = .001), 0.14 (P = .008), −0.26 (P = .001), —0.28 (P = .001); for albumin, creatinine, and hemoglobin values are −0.12 (P = 0.022), 0.31 (P = 0.001), and −0.09 (P = 0.081), respectively. Our BOD index, although constructed in such a way that fewer functional parameters are involved, with CIRS, is able to tap relevant geriatric conditions from both functional and biomedical point of view.