WHO ARE THE OLDER PATIENTS FAILING TO RECOVER MOBILITY AFTER REHABILITATION? (1997)

To the Editor: Many studies aimed at identifying functional and biomedical factors associated with successful rehabilitation indicate that the effectiveness of rehabilitation in older patients is reduced, perhaps because the pathogenic mechanisms leading to disability are complex and include factors frequent or specific to older people (i.e., comorbidity, frailty).1, 2 The purpose of the following report is determination of factors that predict the functional outcomes of 349 sub-acutely ill older patients admitted consecutively and treated in a GEMU (mean LOS = 25.1 ± 11.6 days). In order to focus on the typical geriatric events (i.e., comorbidity), patients admitted for hip fracture or stroke without comorbidity were not considered. Patients with malignancies at terminal stage were also excluded. Age, gender, cognitive impairment (MMSE < 24), depression (GDS > 16), malnutrition (Prognostic Nutritional Index ≥ 35),3 number of drugs, and number and severity of chronic conditions were evaluated as potential prognostic factors. In order to assess if not only chronic diseases, considered individually, but comorbid conditions, as well, affect the outcome of rehabilitation treatment, we utilized the Individual Disease Severity (IDS) score of Greenfield et al.,4 which attributes a score ranging from 0 to 4 to each of the chronic conditions. Patients with high comorbidity were identified as those with two or more diseases scoring ≥ 3 on IDS. Objective evaluation of physical performance was obtained with the Tinetti scale.5 The outcome measure of our analysis was the change in balance and gait after rehabilitation treatment, assessed by the difference between the Tinetti scale score on admission and at discharge. Patients were primarily female (78%) and very old (mean age 79.5 ± 6.7 years). Most had mild cognitive impairment (mean MMSE = 23.0 ± 5.6), were moderately depressed (mean GDS = 12.6 ± 6.2), and had a moderate to high level of functional disability (mean Tinetti scale score 18 ± 9.1) and a high number of concomitant diseases (4.8 ± 1.7) and administered drugs (4.6 ± 1.9). Patients who were malnourished were 36.4% of the population, and those with high comorbidity (two or more diseases scoring ≥ 3 on IDS) were 12.9%. All patients underwent diagnostic, therapeutical, and rehabilitation procedures (including those with high scores on the Tinetti scale). Since functional outcome at discharge was influenced strongly by mobility at baseline, the statistical analysis was performed by stratifying the study population into four classes of patients who were homogeneous for Tinetti scale score on admission. These groups were constructed as follows: 1 Tinetti score 22-28 (n = 170, 48.7%), 2 Tinetti score 15-21 (n = 77, 22.1%), 3 Tinetti score 8-14 (n = 36, 10.3%), and 4 Tinetti score 0-7 (n = 66, 18.9%). The mean scores of the Tinetti scale at discharge were significantly higher than scores on admission. The magnitude of improvements was greater with increasing disability on admission (Table 1). Clinical factors predicting unsuccessful rehabilitation were identified in autoregressive linear models predicting Tinetti score at discharge after adjusting for Tinetti score at baseline. For each predictor, a single model was fitted that included the main effect of the predictor and its interaction with the baseline Tinetti score. Age, gender, number of drugs, and diagnosis of specific clinical conditions were not associated with different outcomes (P > .25). In all these models also the interaction terms were never statistically significant (P > .32). Cognitive impairment and depression were associated with lower Tinetti score at discharge (P = .022 and P = .018, respectively), and these effects were consistent across strata of Tinetti score on admission (the interaction terms were not significant: P > .50). Comorbidity and malnutrition were also associated with poorer Tinetti score at discharge, but the effect was greater in subjects in the lower strata of Tinetti score at baseline (the interaction term was significant at P = .002 and P = .040, respectively). A summary multivariable model was created and included, as independent variables, baseline Tinetti score, depression, cognitive impairment, comorbidity and its interaction with Tinetti score on admission, and malnutrition and its interaction with Tinetti score on admission. All the predictors and their interactions that were significant in the previous analyses remained statistically significant in the multivariable model. The coefficients of this final model were used to obtain adjusted estimates of the Tinetti score at discharge in those with and those without negative prognostic factors within each mobility group. Differences between these estimated values indicate the independent effect of each predictor on recovery of mobility. The clinical implications of these results can be understood better by looking at Figure 1. Independent of other prognostic factors and of Tinetti score at baseline, patients who are cognitively impaired can be expected to show, on average, a Tinetti score at discharge 1 point lower than that of cognitively intact patients. Similarly, depressed patients can be expected to show, on average, a Tinetti score at discharge about 1 point lower than nondepressed patients. However, the magnitude of the lack of improvement in Tinetti score at discharge associated with comorbidity ranged from 1 in those with top mobility to 5.5 points in those with poorest mobility. Analogously, the effect of malnutrition ranged from 0.5 to 3.5 points. . Estimated lack of improvement on Tinetti score at discharge, as a result of poor cognition, depression, high comorbidity, and malnutrition, across levels of Tinetti score on admission. These findings indicate that somatic conditions (comorbidity and malnutrition) have a greater impact on mobility than cognitive impairment and depression.