Usefulness of the Functional Independence Measure (FIM), its subscales and individual items as outcome measures in Guillain Barr?? syndrome

Introduction With the virtual elimination of poliomyelitis, Guillain Barré syndrome (GBS) has become the most common cause of neuromuscular paralysis in Western countries, with an annual incidence of 0.75 to 2.0 per 100 000 of the population (Ropper, 1992). The condition is characterized by progressive and often profound weakness with those affected reaching the nadir within one month followed by a variable course of recovery over a period of weeks to several months. Even when intensive care facilities are available, up to 10% of patients may die in the acute phase of the illness and 20% are left with some disability one year after onset (Raphael et al., 1984; Winer et al., 1988). Approximately 40% of the patients who are hospitalized with GBS will require inpatient rehabilitation (Zelig et al., 1988). Rehabilitation is directed at managing disability and minimizing handicap and it is imperative that outcome measures used reflect these aims. A review article by Molenaar et al. (1995) has highlighted the lack of the use of disability and handicap measures in peripheral neuropathies generally but described disability measures as being used in the cited references on GBS. However, these papers concentrated solely on ambulation. GBS can result in quadriparesis, cranial nerve weakness with difficulty in communication and upper limb function as well as mobility problems. The Functional Independence Measure (FIM), which rates 18 activities of daily living, has been increasingly adopted as a minimal data set to evaluate progress in rehabilitation. We describe the level of disability on admission and at discharge from inpatient rehabilitation in a consecutive series of GBS patients referred to a regional neurorehabilitation unit. Material and method The neurorehabilitation unit, Astley Ainslie Hospital, Edinburgh, provides inpatient rehabilitation to a population of approximately 1.2 million. This study describes the progress of consecutive patients admitted with a diagnosis of GBS over the three-and-a-half year period of March 1994 to September 1998. A total of 62 patients with polyneuropathy were identified and of these, 29 patients fulfilled the diagnostic criteria for GBS as described by Asbury and adopted by the National Institute of Neurological and Communicative Disorders and Stroke (NINDS), USA (Asbury and Cornblath, 1990). In addition to demographic details, the mode of onset, antecedent infections/inoculation, clinical course prior to rehabilitation and the point of maximum neurologic dysfunction (disease nadir) were recorded. Factors thought to affect outcome, such as the need for ventilation during the initial phase of illness, time to disease nadir, and length of hospital stay (in rehabilitation unit), were analysed to look for correlation, if any, with total FIM score, motor and cognitive subscale scores as well as scores of individual FIM items. The Functional Independence Measure (FIM) instrument is a minimal data set designed to assess functional independence. It consists of 18 individual items (Box 1) arranged in four dimensions (Stineman et al., 1997) as shown in Figure 1.Fig. 1: Dimensionality of the FIM (after Stineman et al., 1997).Box. 1: The Functional Independence Measure: itemsEach individual FIM item is scored on a scale of 1 to 7, depending on the person's level of dependency for each item (Box 2). A minimum score of 1 indicates total dependence and a maximum score of 7 total independence. The FIM was recorded routinely at admission and at intervals of four weeks thereafter until discharge.Box. 2: The Functional Independence Measure: scoring methodAs the FIM is made up of numerically labelled but actually ordinal ratings, nonparametric statistics were used to analyse the data. Results One of the 29 patients with GBS admitted to the unit, a 64-year-old man, was excluded from the study because his condition deteriorated rapidly and he died within 10 days of admission to the neurorehabilitation unit. The remaining 28 comprised a group of 15 men and 13 women. The mean age for men was 54.3 years with a minimum of 18 years and a maximum of 83 years. The mean age for women was 60.2 years with a minimum of 17 years and a maximum of 77 years. The change in individual FIM items over time is reflected in Table 1 and Figure 2.Table 1: . Change in individual FIM items over time (n = 28)Fig. 2: Admission and discharge group mean FIM scores for all patients (n = 28).For self-care items the group mean FIM scores on admission ranged from 3.57 to 4.96 and at the time of discharge varied between 5.64 and 6.50. The low scores for dressing of the lower body, toileting and bathing reflect difficulty not only with ambulation but also with reaching and postural balance, continuing problems which lead to lower discharge FIM scores for these items. Nevertheless, the change in group mean FIM score from admission to discharge is statistically significant for each of the self-care items. For bowel and bladder management the group mean FIM scores on admission (4.79 and 5.07) are indicative of the need for supervision, help to set up equipment or incidental help with placement of clothes. Again, the group mean FIM score on discharge shows a statistically significant increase. On admission, group mean FIM scores are lowest for bath transfer (3.64) followed by toilet transfer (3.86) and bed–chair transfer (3.93) as physical help, with lifting, from the attendant was required. The lower group mean discharge FIM score for bathing (5.64) is owing to the need for supervision or help to set up the necessary equipment despite statistically significant increase in FIM scores across the board for all transfers. As expected, the lowest group mean FIM score on admission is for stairs (1.79) as patients are unable to manage stairs without assistance of two persons and also requiring assistance for ambulation (3.75). Gratifyingly, by the end of inpatient rehabilitation the scores have improved to 4.79 and 6.07 respectively although the need for contact guarding or steadying to go up and down 12 to 14 stairs remains. The group mean FIM scores for items of communication and social cognition varied between 6.14 for problem solving to 6.58 for expression on admission and between 6.68 for problem solving to 6.93 for memory at the time of discharge. The increase was statistically significant for all items except comprehension and expression. FIM scores in ventilated versus not-ventilated patients Those who were ventilated in the acute phase of the illness had lower total FIM scores and Cognitive FIM subscale scores on admission than those who were not ventilated (U = 35.0, P = 0.041;U = 21.5, P = 0.005 respectively). Ventilated patients also had lower motor FIM subscale score on admission than those who were not but the difference was not significant (U = 44.5, P = 0.124). At discharge the difference between the two groups for Total FIM score, Cognitive FIM subscore and Motor FIM subscore was not significant (U = 70.0, P = 0.852;U = 53.0, P = 0.215;U = 72.5, P = 0.957 respectively). Length of stay in ventilated versus not-ventilated patients Ventilated patients had longer inpatient rehabilitation but the difference was not statistically significant. Length of stay and FIM score There was a significant correlation between length of stay in the rehabilitation unit and Total FIM scores on admission and discharge. Patients with longer length of stay had lower admission Total FIM scores and discharge Total FIM scores (rs = – 0.678, P < 0.001; and rs = – 0.581, P = 0.001 respectively). Antecedent infection/inoculation and FIM score There were no significant differences between patients who had antecedent infection/inoculation and those who had none on admission or discharge FIM scores Disease nadir There were no significant correlations with length of time between onset and disease nadir and Total FIM score, Cognitive FIM subscore or Motor FIM subscore either on admission or discharge from the unit. The results show a significant improvement in all areas of function, as measured on the FIM between admission to and discharge from the rehabilitation unit (Total FIM, Cognitive FIM subscore and Motor FIM subscores being Z = – 4.62, P < 0.001; Z = – 3.75, P < 0.001; Z = – 4.54, P < 0.001 respectively). Analysis of motor FIM subscore domains showed an especially significant improvement in function over mobility, self-care and sphincter domains (Mobility items score P < 0.001; self-care items score Z = – 4.29, P < 0.001; Sphincter items score Z = – 3.60, P < 0.001). Discussion Quantification of function has become a basic tool in everyday rehabilitation work, inpatient selection before admission and in monitoring progress during treatment. Unfortunately, textbooks and review articles concentrate on motor impairments, clinical features, complications and treatment modalities in GBS. In an acute rehabilitation setting FIM is one of the most widely used instruments for determining patients’ rehabilitation relevant clinical status (Fiedler et al., 1996). Several studies have demonstrated the interrater reliability of the FIM (Hamilton et al., 1994). Meythaler et al. (1997) have looked at prognostic factors such as anaemia, dysautonomia, peripheral nerve function, disease nadir and ventilator support and their relationship to acute care length of stay, rehabilitation length of stay, FIM Rasch converted scores and cost of acute care and inpatient rehabilitation, while we have focused on inpatient rehabilitation length of stay because of the obvious implication it has on bed occupancy in these days of bed crisis. In agreement with Meythaler et al., we found no correlation between disease nadir and inpatient rehabilitation stay. We also found that patients requiring ventilation had lower motor and cognitive FIM subscale score on admission to inpatient rehabilitation but by the time of discharge the difference was not statistically significant. However, unlike them, we found that although ventilated patients had longer inpatient rehabilitation, this difference was not statistically significant. Some of the discrepancy might be owing to the fact that their patients had both acute care and inpatient rehabilitation in the same centre, implying seamless care, while our cohort had their acute care in the neurology ward of another tertiary care hospital before transfer to us. Additionally, unlike them we have concentrated on the most finely grained individual FIM item score along with scores of the ADL and mobility domains of the motor subscale of FIM as well as cognitive subscale of FIM and their correlation to length of inpatient rehabilitation, as it is more reflective of the evolving functional profile during rehabilitation As expected, activities in the mobility subscale, being dependent on the use of legs, were most severely affected. Not surprisingly, activities of self-care domain, which depend more on the use of arms, were also considerably affected, as were transfers, which depended on the use of both arms and legs. The improvement in the physical functioning had an indirect effect on the cognitive items with the most pronounced result seen in social interaction Change over time was related to degree of disability on admission. As expected, change over time was smallest on the cognitive items but the results still showed a significant improvement. While there has been no statistically significant correlation between factors such as prodromal symptoms, disease nadir, ventilation and outcome, FIM as an instrument is sufficiently sensitive in detecting disability and change over time during the rehabilitation of GBS patients. Moreover, not only Total FIM score but also Cognitive FIM subscore and Motor FIM subscore as well as mobility, self-care and sphincter domains of Motor FIM subscore reflect this in GBS patients in a rehabilitation setting.