Cut‐off values of Functional Independence Measure scores for discharge destination

The number of hospitalized elderly patients has been steadily increasing. Ideally, elderly inpatients are rehabilitated by physiatrists to improve their functional capacity during their hospital stay, and then discharged back to their homes. Clinically, it is important to predict whether such elderly patients are able to return home after discharge. The Functional Independence Measure (FIM) motor scale is used clinically to measure patient progress and to assess rehabilitation outcome. We focused on elderly inpatients who received comprehensive rehabilitation services during their hospital stay, and calculated statistically the cut-off values of FIM scores for inpatients to return home after discharge. A total of 725 elderly patients admitted to Tottori Municipal Hospital, Tottori, Japan, between January 2013 and December 2013 were enrolled (men n = 256, mean age 81.3 ± 6.4 years; women n = 469, mean age 83.8 ± 6.8 years; P < 0.05, Mann–Whitney U-test). All patients had received standard rehabilitation treatment by attending physicians, including range-of-motion exercises, resistance training, physical restoration, movement exercises and ambulation exercises. Physical ability was assessed using FIM scores at admission and again at discharge. FIM scores to predict whether the patient was able to return home after discharge were examined by receiver operating characteristic (ROC) curve, and their respective areas under the curve (AUC), in which sensitivity is plotted as a function of 1-specificity. This study was approved by the ethics committee of Tottori Municipal Hospital (no. 1153). As shown in AUC values of Figure 1, all curves provided only moderate sensitivity or specificity in predicting discharge destination for elderly inpatients. Cut-off values of FIM score to return home at admission were calculated (men 54, sensitivity 0.71, specificity 0.83; women 51, sensitivity 0.74, specificity 0.76). Next, cutoff values of FIM score to return home at discharge were calculated (men 76, sensitivity 0.75, specificity 0.82; women 85, sensitivity 0.71, specificity 0.80). Finally, cut-off values of FIM efficiency to return home were calculated (men 0.80, sensitivity 0.54, specificity 0.79; women 0.32, sensitivity 0.75, specificity 0.55). FIM scores reflect the change in performance of activities of daily living, and can help determine the patient’s discharge destination. It has been reported that patients with low FIM scores at discharge were likely to be discharged to a care facility, and those with high FIM scores at discharge usually returned home. In the present study, we statistically calculated FIM scores to determine the cut-off values that determined whether elderly inpatients were able to return home after discharge. We have considered that it is difficult to prove the clinical significance of FIM score at admission, as the cause of hospitalization should differ among elderly patients. Therefore, we focused on FIM score at discharge, because all elderly patients had received standard rehabilitation treatment during their hospital stay. We found for the first time that the FIM scores of elderly women who returned home after discharge were higher than those of elderly men (at discharge, men score 76, women score 85); this suggests higher FIM scores might be required for female patients to return home. In Japan, a wife’s duties, such as taking care of one’s family including one’s husband, are generally still an accepted concept. Women might thus be tacitly required to take care of their family despite a weakened state. We found a difference between men and women in the cut-off values of FIM efficiency to return home (men 0.80; women 0.32). We have considered that one of the reasons for this is the statistically significant difference in age, as described above (P < 0.05, Mann–Whitney U-test). The age of inpatients is an important factor when physicians estimate FIM efficiency by rehabilitation in a hospital stay. Although the present study is inherently limited by its single-center selection bias, as all patients were assessed at our hospital, the cut-off values obtained might be useful information for elderly inpatients and physiatrists working together toward their return home after discharge.