Comparison of logistic regression and neural networks to predict rehospitalization in patients with stroke.

CONTEXT: Rehospitalization following inpatient medical rehabilitation has important health and economic implications for patients who have experienced a stroke. OBJECTIVE: Compare logistic regression and neural networks in predicting rehospitalization at 3-6-month follow-up for patients with stroke discharged from medical rehabilitation. DESIGN: The study was retrospective using information from a national database representative of medical rehabilitation patients across the US. SETTING: Information submitted to the Uniform Data System for Medical Rehabilitation from 1997 and 1998 by 167 hospital and rehabilitation facilities from 40 states was examined. PARTICIPANTS: 9584 patient records were included in the sample. The mean age was 70.74 years (SD = 12.87). The sample included 51.6% females and was 77.6% non-Hispanic White with an average length of stay of 21.47 days (SD = 15.47). MAIN OUTCOME MEASURES: Hospital readmission from 80 to 180 days following discharge. RESULTS: Statistically significant variables (P <.05) in the logistic model included sphincter control, self-care ability, age, marital status, ethnicity and length of stay. Area under the ROC curves were 0.68 and 0.74 for logistic regression and neural network analysis, respectively. The Hosmer-Lemeshow goodness-of-fit chi-square was 11.32 (df = 8, P = 0.22) for neural network analysis and 16.33 (df = 8, P = 0.11) for logistic regression. Calibration curves indicated a slightly better fit for the neural network model. CONCLUSION: There was no statistically significant or practical advantage in predicting hospital readmission using neural network analysis in comparison to logistic regression for persons who experienced a stroke and received medical rehabilitation during the period of the study.

Development of function-related groups version 2.0: a classification system for medical rehabilitation.

OBJECTIVE: To present a new version (2.0) of the Functional Independence Measure-Function Related Group (FIM-FRG) case-mix measure. DATA SOURCE/STUDY SETTING: 85,447 patient discharges from 252 freestanding facilities and hospital units contained in the 1992 Uniform Data System for Medical Rehabilitation. STUDY DESIGN: Patient impairment category, functional status at admission to rehabilitation, and patient age were used to develop groups that were homogeneous with respect to length of stay. Within each impairment category patients were randomly assigned to one data set to create the system (through recursive partitioning) or a second set for validation. Clinical and statistical criteria were used to increase the percentage of patients classified, expand the impairment categories of FIM-FRGs Version 1.1, and evaluate the incremental predictive ability of coexisting medical diagnoses. Predictive stability over time was evaluated using 1990 discharges. PRINCIPAL FINDINGS: In Version 2.0, the percentage of patients classified was increased to 92 percent. Version 2.0 includes two new impairment categories and separate groups for patients admitted to rehabilitation for evaluation only. Coexisting medical diagnoses did not improve LOS prediction. The system explains 31.7 percent of the variance in the logarithm of LOS in the 1992 validation sample, and 31.0 percent in 1990 discharges. CONCLUSIONS: FIM-FRGs Version 2.0 includes more specific impairment categories, classifies a higher percentage of patient discharges, and appears sufficiently stable over time to form the basis of a payment system for inpatient medical rehabilitation.

Noninvasive assessment of internal thoracic artery for reoperative coronary artery surgery.

To determine whether previous sternotomy alters internal thoracic artery (ITA) anatomy and flow characteristics, a duplex scanner was used for noninvasive evaluation of the ITA in 59 patients who were scheduled for reoperative coronary artery bypass surgery. The left ITA was insonated through the third intercostal space by use of a duplex scanner (5.0 MHz probe). Measurements of the ITA diameter (mm) and peak systolic velocity (cm/sec) were obtained; ITA flow was calculated from velocity and cross-sectional area. These findings were compared with the values obtained from 105 patients who were scheduled to undergo first-time (primary) coronary artery surgery during the same time period. In the reoperative group, preoperative mean ITA diameter was 2.26 +/- 0.06 mm; this was not significantly different from the primary group's mean ITA diameter of 2.15 +/- 0.04 mm (p = 0.09). Mean peak systolic velocity was 79.9 +/- 2.4 cm/sec and calculated systolic blood flow was 204.6 +/- 13.1 ml/min in the reoperative patients, as compared with 83.3 +/- 2.1 cm/sec and 189.5 +/- 8.6 ml/min in the primary group, respectively. Values were similar in both groups for the peak systolic velocity (p = 0.31) and calculated systolic blood flow (p = 0.32). These results suggest that previous heart surgery or sternotomy does not adversely affect ITA anatomy and flow characteristics. We conclude that ultrasonic imaging is an easily applicable technique for preoperative assessment of ITA in patients who have undergone previous sternotomy.

The Interest Checklist: a factor analysis.

OBJECTIVE: The purpose of this study was to determine whether the 80 items on the Interest Checklist empirically cluster into the five categories of interests described by Matsutsuyu, the developer of the tool. METHOD: The Interest Checklist was administered to 367 subjects classified in three subgroups: students, working adults, and retired elderly persons. An 80-item correlation matrix was formed from the responses to the Interest Checklist for each subgroup and then used in a factor analysis model to identify the underlying structure or domains of interest. RESULTS: Results indicated that the Social Recreation theoretical category was empirically independent for all three subgroups; the Physical Sports and Cultural/Educational theoretical categories were empirically independent for only the college students and working adults; and the Manual Skills theoretical category was empirically independent for only the working adults. CONCLUSION: Although therapists should continue to be cautious in their interpretation of patients' Interest Checklist scores, the tool is useful for identifying patients' interests in order to choose meaningful activities for therapy.

Mortality of a municipal-worker cohort: IV. Fire fighters.

Morbidity and mortality studies of fire fighters have produced varied and inconsistent findings regarding the potential chronic effects of fire fighting including respiratory disease, cardiovascular disease, and cancer. The mortality experience of 1,867 white male fire fighters who were employed for the City of Buffalo a minimum of five years with at least one year as a fire fighter was studied. Vital status was determined for 99% of the cohort, resulting in 470 observed deaths. The fire fighter cohort was characteristic of a healthy worker population. All-cause mortality was close to the expected standardized mortality ratio (SMR) = 95, and significantly lower than expected mortality was seen for all external causes (SMR = 67)--in particular, for suicide (SMR = 21) and respiratory diseases (SMR = 48). Significantly elevated SMRs were found for benign neoplasms (SMR = 417), cancer of the colon (SMR = 183), and cancer of the bladder (SMR = 286). Cause-specific mortality is presented by number of years employed, calendar year of death, year of hire, and latency. Cancer mortality was significantly higher in the long-term fire fighters, and risk of mortality from all malignant neoplasms tended to increase with increasing latency. Patterns in risk of mortality among fire fighters for cancers of the bladder, colon, and brain are intriguing. Additional follow-up of this cohort and initiation of cancer morbidity studies would be helpful in further clarifying the potential long-term effects of fire fighting on cancer risk.

Functional assessment scales. A study of persons after traumatic brain injury.

The purpose of this study was to investigate disability in persons after traumatic brain injury (TBI) by using combinations of functional assessment item, subscale, domain, and full-scale scores to predict (1) the need for assistance in performance of specific physical care tasks measured in minutes of help per day provided by another person in the home and (2) the subject's level of satisfaction with life in general. This study also sought to account for the amount of supervision that persons with TBI may require beyond that needed for physical care tasks. The Functional Independence Measure (FIM) contributed to prediction of subjects' physical care needs. A single-point change in total FIM score was equivalent to an average of about 5 min of help from another person per day. Satisfaction with life in general was predicted mainly by the depression subscale of the Brief Symptom Inventory. However, this latter prediction was only true when subjects who required constant supervision were removed from analysis. Thus, the amount of supervision required by persons with TBI is an important variable to study in this population. Three categories of supervision were identified: constant (all of the time), periodic (daily or weekly), or not at all. The need for supervision and physical assistance from another person and a subject's satisfaction with life in general are important standards by which functional assessment instruments may be compared to reflect, in pragmatic terms, the impact of disability on the lives of individuals and on human and economic resources of the community.

Discharge outcome after stroke rehabilitation.

BACKGROUND AND PURPOSE: The purpose of this study was to examine the relations between host characteristics (age and side of body affected) and program variables (lengths of stay in acute care and rehabilitation, levels of functional ability at admission and discharge, and rates of community discharge). METHODS: A sample of 7,905 patients was drawn from medical rehabilitation facilities enrolled in the Uniform Data System for Medical Rehabilitation who were admitted and discharged for the first time between January 1988 and June 1989. Data were analyzed using either chi 2 tests or z normal tests of proportions, and analyses of variance (ANOVA) and/or t tests. Significance was set at p less than 0.05, and statistically significant F ratios were examined using Student-Newman-Keuls tests. RESULTS: The average age of patients was 70.7 years (24% less than 65 years, 53% 65-79 years, and 23% greater than 79 years). Lengths of stay in acute care and rehabilitation, admission and discharge functional independence ratings, and rates of community discharge were generally inversely related to patient age. Patients with bilateral paresis had lower rates of community discharge than those with unilateral paresis, although this distinction was not evident in the older group. CONCLUSIONS: Results showed that older age and bilateral paresis are negatively associated with levels of independence at admission and discharge and with rates of community discharge.

A brief outpatient functional assessment measure: validity using Rasch measures.

The Medical Rehabilitation Follow Along (MRFA(TM)) is a brief outpatient functional assessment measure that was developed using Rasch analysis. The MRFA currently has musculoskeletal, neurologic, multiple sclerosis, cardiac, and pulmonary forms. Using Rasch scoring and selected scales, the 31-item musculoskeletal form of the MRFA was compared with and contrasted to a measure of general health status, the Medical Outcomes Trust SF-36. Content, construct, and criterion validity were addressed using scale scores before and after outpatient rehabilitation, as well as therapist ratings of improvement. The results supported the validity of inferences made from the MRFA scales using Rasch measures for persons with musculoskeletal problems. Rasch and raw scoring provided similar results with respect to the validity of the MRFA scales. Implications for the use of Rasch and raw scoring approaches with the MRFA are discussed.

Interrater reliability of the 7-level functional independence measure (FIM)

The Functional Independence Measure (FIM) is an 18-item, 7-level scale developed to uniformly assess severity of patient disability and medical rehabilitation functional outcome. FIM interrater reliability in the clinical setting is reported here. Clinicians from 89 US inpatient comprehensive medical rehabilitation facilities newly subscribing to the uniform Data System for Medical Rehabilitation from January 1988-June 1990 evaluated 1018 patients with the FIM. FIM total, domain and subscale score intraclass correlation coefficients (ICC) were calculated using ANOVA; FIM item score agreement was assessed with unweighted Kappa coefficient. Total FIM ICC was 0.96; motor domain 0.96 and cognitive domain 0.91; subscale score range: 0.89 (social cognition) to 0.94 (self-care). FIM item Kappa range: 0.53 (memory) to 0.66 (stair climbing). A subset of 24 facilities meeting UDSMR data aggregation reliability criteria had Intraclass and Kappa coefficients exceeding those for all facilities. It is concluded that the 7-level FIM is reliable when used by trained/tested inpatient medical rehabilitation clinicians.

Mortality of a municipal worker cohort: III. Police officers.

Very little is known about the long-term health risks associated with the high stress police officer occupation. We report here on a retrospective cohort of 2,376 ever-employed white male police officers employed between January 1950 and October 1979. Vital status was obtained for 96%, the officers accumulating a total of 39,462 person-years. Six-hundred sixty-one deaths were observed. Total mortality from all causes was comparable to that of the overall U.S. white male population (standardized mortality ratio [SMR] = 106). Significantly increased mortality was seen for all malignant neoplasms combined (SMR = 127), cancer of the esophagus (SMR = 286), and cancer of the colon (SMR = 180). Significantly lower than expected mortality was seen for infectious diseases (SMR = 26), respiratory diseases (SMR = 64), and accidents (SMR = 60). Internal cohort comparisons revealed that policeman exhibited significantly higher mortality from suicide compared to all other municipal employees (rate ratio = 2.9). Analysis of mortality by length of service as a police officer showed that those employed 10-19 years were at significantly increased risk of digestive cancers and cancers of the colon and lymphatic and hematopoietic tissues and decreased risk for all diseases of the circulatory system. Policeman employed more than 40 years had significantly elevated SMRs for all causes, all malignant neoplasms combined, digestive cancers, cancers of the bladder and lymphatic and hematopoietic tissues, and arteriosclerotic heart disease. Risk of mortality from arteriosclerotic heart disease tended to increase with increasing years employed. These findings are discussed in light of the police stress literature. The hypotheses generated in this study must be tested through study of the role of important confounders including reactions to stress on the job.

Mortality of a municipal worker cohort: II. Females.

Women have become an increasingly important segment of the total work force, yet there are very few published occupational mortality studies of female workers. This paper reports the findings of a retrospective cohort mortality study of 1,371 full-time female municipal employees of the City of Buffalo, New York, who were employed at least 1 day between January 1, 1950, and October 1, 1979, and who worked a minimum of 5 years. Vital status was ascertained for 88% of the female cohort, resulting in the identification of 214 observed deaths. This predominantly white-collar, service-oriented female cohort demonstrated significantly lower mortality than that expected based on U.S. mortality rates for white females. This strong "healthy-worker effect" was consistent across the time period of the study, across cause-specific mortality especially for all malignant neoplasms and all diseases of the circulatory system, and across different workers groups. Findings are discussed in light of the methodological issues involved in occupational studies of female workers.

Functional assessment scales: a study of persons after stroke.

The purpose of this study was to investigate disability in persons after stroke by using combinations of functional assessment item, subscale, domain, and full-scale scores, to predict (1) the burden of care measured in minutes of assistance provided per day by another person in the home, and (2) the subject's level of satisfaction with life in general. The Functional Independence Measure (FIM) and the Sickness Impact Profile (SIP) each contributed to prediction of the subject's physical care needs. A change in total FIM score of one point (range, 61 to 126) was equivalent to an average of 2.19 minutes of help from another person per day and a change in one point in the SIP physical dysfunction (SIPPHYS) score (range, 4.0% to 57.4%) was equivalent to an average of 3.32 minutes. Along with the Brief Symptom Inventory and a measure of visual ability, the FIM contributed to predicting the patient's general satisfaction as well. The burden of care and subjective satisfaction with life in general are important standards by which functional assessment instruments may be compared to reflect, in pragmatic terms, the impact of disability on the lives of individuals and on the human and economic resources of the community.

The reliability of the functional independence measure: a quantitative review.

OBJECTIVE: The reliability of the Functional Independence Measure (FIMSM) for adults was examined using procedures of meta-analysis. DATA SOURCES: Eleven published studies reporting estimates of reliability for the FIM were located using computer searches of Index Medicus, Psychological Abstracts, the Functional Assessment Information Service, and citation tracking. STUDY SELECTION: Studies were identified and coded based on type of reliability (interrater, test-retest, or equivalence), method of data analysis, size of sample, and training or experience of raters. DATA EXTRACTION: Information from the articles was coded by two independent raters. Interrater reliability for coding all elements included in the analysis ranged from .89 to 1.00. DATA SYNTHESIS: The 11 investigations included a total of 1,568 patients and produced 221 reliability coefficients. The majority of the reliability values (81%) were from interrater reliability studies, and the intraclass correlation coefficient (ICC) was the most commonly used statistical procedure to compute reliability. The reported reliability values were converted to a common correlation metric and aggregated across the 11 studies. The results revealed a median interrater reliability for the total FIM of .95 and median test-retest and equivalence reliability values of .95 and .92, respectively. The median reliability values for the six FIM subscales ranged from .95 for Self-Care to .78 for Social Cognition. For the individual FIM items, median reliability values varied from .90 for Toilet Transfer to .61 for Comprehension. Median and mean reliability coefficients for FIM motor items were generally higher than for items in the cognitive or communication subscales. CONCLUSIONS: Based on the 11 studies examined in this review the FIM demonstrated acceptable reliability across a wide variety of settings, raters, and patients.

Relation of disability costs to function: spinal cord injury.

OBJECTIVE: This study evaluated the validity of the Functional Independence Measure (FIM instrument) in predicting (1) the number of minutes of daily assistance provided, (2) the cost of durable goods currently used, and (3) the number of paid helper hours provided daily to persons with spinal cord injury living in the community. DESIGN: A cross-sectional study. SUBJECTS: One hundred nine persons with spinal cord injury who were a median 6 years postdischarge from initial medical rehabilitation. RESULTS: A significant inverse linear relationship was observed between FIM scores and the square root values of the three cost-related measures. The FIM-18 and the FIM motor scores were the best single predictors of the square root of minutes of assistance (paid and/or unpaid) per day, explaining 85% of variance. The FIM motor measure was the best single predictor of square root of cost of durable goods, explaining 29% of variance. The Self-Care, FIM motor, and FIM-18 scores equally predicted square root of hours of paid help per day, explaining 58% of variance. CONCLUSION: The findings indicate FIM-related scores predict the amount of assistance needed and certain costs for persons with spinal cord injury disability.

Functional task benchmarks for stroke rehabilitation.

OBJECTIVE: To determine typical outcome "benchmarks" for 18 functional tasks in patients undergoing stroke rehabilitation. The benchmarks are intended to serve as points of reference to which the outcomes of patients with similar impairments and degrees of disability can be compared. SUBJECTS: Records from 26,339 stroke patients discharged from 252 inpatient facilities across the United States that submitted 1992 data to the Uniform Data System for Medical Rehabilitation. METHODS: Stroke impairment was detailed as the presence or absence of hemiparesis resulting from stroke and the side(s) of involvement. Within each of five stroke impairment categories, patients were further classified by the Functional Independence Measure-Function-Related Groups (FIM-FRGs) into nine syndromes by degree of disability (admission motor and cognitive FIM scores) and by age. Outcomes were determined for each stroke syndrome at patients' discharge from medical rehabilitation. MAIN OUTCOME MEASURES: Patients' median performance levels on each of the 18 items making up the FIM, length of stay, and community discharge rates. RESULTS: The majority of patients whose admission motor FIM scores were above 37 were able to eat, groom, dress the upper body, and manage bladder and bowel functions independently by discharge. In addition to these tasks, most of those whose motor FIM scores were above 55 were able to dress the lower body, bathe, and transfer onto a chair/bed or toilet. The majority of patients whose initial motor FIM scores were above 62 points and whose cognitive FIM scores were above 30 gained independence in most tasks, including stair climbing and tub transfers. Community discharge rates ranged from 51.6% for the group of patients with the most severe disabilities to 99.2% for the group with the least severe disabilities. CONCLUSION: The clinician can apply these benchmarks to guideline development and quality improvement, and in establishing patient goals.

A prediction model for functional recovery in stroke.

BACKGROUND AND PURPOSE: Stroke-related physical disability can diminish quality of daily living, place care burden on families, and increase need for long-term institutionalization. We developed a prognostic index for use in research and with potential for adaptation to clinical practice that establishes the likelihood of an individual achieving a specific stage of functional recovery after stroke rehabilitation. METHODS: We constructed the index using logistic regression based on 3760 patient records from 96 rehabilitation facilities in 31 states. The stage, as measured by the Functional Independence Measure, includes achievement of the following: independence in eating, grooming, and dressing the upper body; continence in bowel and bladder; and transfer between a bed and chair with supervision only. RESULTS: This stage was achieved by 26.1% of patients functioning below it at rehabilitation admission. Disability onset of less than 60 days was associated with more than a 3-fold increase in the likelihood of achieving the stage (adjusted odds ratio, 3.5; 95% confidence interval, 2.0 to 6.0). Each eight-point increase in an eight-item activities of daily living score, measured at admission to rehabilitation, increased the odds 2.5-fold (95% confidence interval, 2.3 to 2.8). For those living alone or employed before the stroke, the odds of achieving the stage increased by factors of 1.3 and 2.2, respectively. The index showed minimal shrinkage on cross validation. The achievement of this profile of function is important because 95.3% of stroke patients who achieved or exceeded it were discharged home, as opposed to only 66.8% of those who did not achieve it. CONCLUSIONS: The index can be used to establish prognoses for individual stroke patients at admission to rehabilitation with regard to achieving this stage. Achievement of the stage is associated with a high likelihood of discharge to home.

Mortality of workers in an automobile engine and parts manufacturing complex.

A proportionate mortality ratio (PMR) study was conducted using data on workers from three local unions representing an integrated automobile factory composed of forge, foundry, and engine (machine and assembly) plants. Ninety four percent of the death certificates were obtained for all active and non-active workers who died during the period 1 January 1970 to 31 December 1979 and were vested in union and company benefit programmes. Observed numbers of deaths were compared with expected numbers based on two standards, the proportionate mortality among men in the United States 1970-9 and among men in Erie County 1975. There was close agreement between the number of observed and expected deaths by either standard of comparison among white auto workers in the forge and foundry plants. Valid analyses of cause specific mortality among non-whites could be conducted for the foundry plant only. Although there was raised PMR for deaths due to diseases of the circulatory system using the Erie County standard, none of the other cause specific PMRs was significant. Although based on small numbers, the risk of cancer of the lung was significantly high in non-whites under age 50 in the foundry (PMR = 2.6; p less than 0.05). The cause specific PMRs for whites in the engine plant were statistically significant for malignant neoplasms (1.2) and all external causes (0.62) based on the US white male standard. Analysis of cancer specific mortality among white men in the machining/assembly plant showed significant excesses for cancer of the digestive system (PMR=1.5), particularly of the liver (PMR=2.6) and pancreas (PMR=1.9); cancers of the respiratory system (PMR=1.4 using the Erie County standard); and cancer of the urinary bladder (PMR=2.3). Workers employed for more than 20 years showed statistically increased mortality ratios for cancers of the digestive system (1.9), particularly cancer of the pancreas (2.3) and cancer of the rectum (2.8). Individuals whose employment began during or before 1950 exhibited increased PMRs for cancers of the digestive organs (1.8), particularly of the pancreas (2.5) and of the bladder (3.4). Workers whose employment began after 1950, on the other hand, exhibited raised PMRs for cancers of the respiratory system (1.5) and of the kidney (3.2). Since the foundry and forge plants did not start production until 1955, mortality associated with those work settings may be greater in the future.

Length of stay and hospital readmission for persons with disabilities.

OBJECTIVES: Length of stay (LOS) and hospital readmission for persons receiving medical rehabilitation were examined. METHODS: A total of 96,473 patient records (1994-1998) were analyzed. Mean age of patients was 68.97 years; 61% were female and 83% were non-Hispanic White. RESULTS: A decrease in LOS of 6.07 days (SD = 3.23) and increase in hospital readmission were found across all impairment groups (P < .001). Readmission increases ranged from 6.7% for amputations to 1.4% for orthopedic conditions. LOS was longer (2.1 days) for readmitted patients (P < .01). Age was not a significant predictor of rehospitalization. CONCLUSIONS: Understanding variables associated with rehospitalization is important as prospective payment systems are introduced for postacute care.

Intermodal agreement of follow-up telephone functional assessment using the Functional Independence Measure in patients with stroke.

OBJECTIVE: To examine the intermodal agreement of Functional Independence Measure (FIM) ratings when obtained by two commonly used approaches: telephone interview and in-person assessment of functional performance. DESIGN: A random sample of 40 persons with hemiparesis was tested by two registered nurses trained in FIM definitions and telephone interview techniques. The two assessments occurred within 5 days of each other. The raters were blind to previous assessments. The administration of assessments was alternated to minimize bias and order effects. SETTING: All subjects were assessed at home, between 3 and 10 months after discharge from rehabilitation. PATIENTS: The criteria for inclusion were: (1) diagnosis of cerebral vascular accident (CVA); (2) completion of a minimum of 2 weeks in an acute rehabilitation program; (3) currently living at home; (4) living within a 30-mile radius of the hospital; and (5) cognitive and verbal skills adequate to complete a telephone interview. From a population of 103 patients, 40 subjects were randomly selected, 18 women and 22 men ranging in age from 37 to 90 years. MAIN OUTCOME MEASURES: The intermodal agreement between FIM ratings obtained by telephone interview and in-person assessment was examined using the intraclass correlation (ICC). FIM item scores were analyzed for agreement using the Kappa coefficient. The stability of the responses was determined by computing the coefficient of variation and plotting the data to visually examine the relationship between the two methods of administration. RESULTS: Data analysis revealed that there was no statistically significant difference (p > .05) between the two methods of administration for total FIM score. The total FIM ICC was .97. ICC values for FIM subscales ranged from .85 to .98, except for social cognition. Kappa scores for noncognitive items ranged from .49 (bowel movement) to .93 (grooming). The coefficient of variation computed to examine cognitive and communication items with reduced variability indicated good stability across all items. CONCLUSION: The results indicated good intermodal agreement for follow-up telephone assessment using the Functional Independence Measure. The findings were limited to persons with effective communication skills.