Inpatient Rehabilitation Outcome After Hip Fracture Surgery in Elderly Patients: A Prospective Cohort Study of 946 Patients

Methods 

Results 

Nine hundred sixty-two patients over the age of 65 were hospitalized in the geriatric ward for rehabilitation after surgery for hip fracture during the study period. A random sample over a period of 1 year in the orthopedic surgery department showed that the percentage of elderly patients that were not transferred for rehabilitation was 9.8% of all patients in this age group undergoing surgery for hip fracture.

Sixteen (1.7%) of the patients who were transferred for rehabilitation died during its course. The other 946 patients who were discharged at the end of the hospitalization comprised the study group. Table 1 presents the principal characteristics of the study group, in particular sex, age, cognitive state, length of hospitalization in the orthopedic surgery department, length of hospitalization for rehabilitation in the geriatrics ward, and functional status at the 3 time points in relation to the rehabilitation process.

Table 1. Sociodemographic Characteristics, Functional Status, and Hospitalization Variables of the Study Population (N=946)

	Variable	Value	Range
	Women, n (%)	717(76)	NA
	Mean age ± SD (y)	78.3±7.1	65–98
	Mean MMSE score ± SD⁎	24±5.7	10–30
	Mean prefracture FIM score ± SD	115.0±14.7	45–126
	Mean days in orthopedic surgery ward ± SD	10.7±5.1	2–40
	Mean days hospitalized for rehabilitation ± SD	22.1±8.9	6–47
	Mean admission FIM score ± SD	74.0±16.2	25–108
	Mean discharge FIM score ± SD	89.0±19.5	18–113

Abbreviations: NA, not applicable; SD, standard deviation.

⁎ Available for only 937 of the 946 patients.

Only 8 of the 40 tested variables were significantly and independently associated with absolute efficacy of rehabilitation. These 8 variables are listed in table 2, and their order of importance is expressed by the absolute value of the standardized regression coefficient (β). The positive or negative value of this coefficient reflects a corresponding positive or negative contribution of the specific variable to the absolute efficacy of rehabilitation. The total percentage of the explained variance of the absolute efficacy of rehabilitation accounted for by these variables (adjusted R2) was 31.9%.

Table 2. Results of the Multivariate Analysis

	Variable	Regression Coefficient	Standard Error	β	P	Cumulative Adjusted R2
	Prefracture FIM score (recall)	0.326	0.039	.261	<.001	.176
	Serum albumin at discharge (g/dL)	8.418	1.108	.222	<.001	.260
	MMSE	0.565	0.102	.174	<.001	.293
	Dyspnea on mild exertion, NYHA class III (1=yes, 0=no)	−5.247	1.856	−.080	.005	.301
	Visual impairment (1=yes, 0=no)	−0.070	0.022	−.089	.002	.308
	Age (y)	−0.202	0.075	−.080	.007	.312
	Prior stroke with motor impairment (1=yes, 0=no)	−4.683	1.846	−.072	.011	.316
	Decreased serum folic acid (<3μg/L) (1=yes, 0=no)	−3.999	2.009	−.055	.047	.319

NOTE. Variables independently associated with the absolute efficacy of rehabilitation in the order of their adjusted R2 value.

To avoid the pitfall of overlooking or discounting other important modifiable factors that could be lost in the stepwise regression, we looked at each of the other 4 modifiable factors individually to see if any of them predicts the dependent variable after adjusting for the 4 nonmodifiable covariates (prefracture FIM score, MMSE score, age, prior stroke with motor impairment). This analysis showed that hemoglobin concentration at discharge significantly predicted the dependent variable (P=.009), but elevated serum thyroid-stimulating hormone, decreased serum vitamin B12, and hearing impairment did not.

Discussion 

Two methodologic aspects of our study need to be addressed. First, not all patients who underwent surgical repair of hip fracture were included in the study. This situation led to an inevitable selection bias in the study population. Second, we assessed rehabilitation outcome at the time of discharge from the hospital. We chose this particular point from the entire time sequence of the rehabilitation process that continues beyond discharge as well because we believe that it represents the central point in time in the process. In most cases, completion of the inpatient phase of rehabilitation enables continuation of the process in the framework of the community, where the patient returns to his/her natural environment. It also represents the end of the large expenses incurred in the hospital phase of the process.

Of the 8 parameters that were found in this study to be significantly and independently associated with rehabilitation outcome, 5 were identified in previous studies. However, the point in time and the rehabilitation framework in which the rehabilitation outcome was assessed were different among the various studies and from the present one. These 5 parameters include the prefracture functional status,7, 8, 9, 10, 11, 12, 13, 14 the mental status,9, 10, 12, 13, 14, 15, 16 age,13, 14, 16, 17, 18 previous stroke,19, 20 and serum albumin level.21, 22 In relation to the last variable, our study introduced an important new dimension (ie, that serum albumin level at discharge rather than at admission has a significant association with the outcome of rehabilitation). This result does not enable us to determine whether this positive association represents a cause or an effect of the outcome but does enable us to propose interventions to raise the serum albumin level by appropriate dietary adjustments and supplementation.

Dyspnea on mild exertion (NYHA class III), which was identified in this study as a negative, independent factor associated with rehabilitation outcome, was not reported in previous studies. This significant negative association is striking in light of the absence of such an association for cardiovascular and pulmonary diseases, which are usually the clinical cause of dyspnea, and is in contrast with the results of a previous study in which these diseases were found to have a negative prognostic effect on rehabilitation among hip fracture patients.23 We believe that these findings reflect the fact that only the severe functional impairment caused by these diseases is associated with the outcome of rehabilitation and not the diseases per se.

The negative association between visual impairment and rehabilitation outcome is not surprising. However, it should be noted that this association was not found for hearing impairment. This aspect of the association of visual and hearing impairments with the outcome of rehabilitation in hip fracture patients was described and discussed in a previous article that was dedicated to that issue.3

The finding that decreased serum folic acid has a negative association with the success of rehabilitation after hip fracture is interesting and expresses, in our opinion, the influence of the nutritional state of the patients in the weeks before the hip fracture, in contrast to decreased serum vitamin B12 that reflects a more prolonged nutritional deficit that was not found in our study to be an independently significant factor for the success of rehabilitation. During the course of rehabilitation, patients who were found to have decreased serum folic acid levels received supplementation. Despite this strategy, a decreased serum folic acid level at the beginning of rehabilitation had a negative association with its outcome. We assume that the short period of time in which this treatment was given in relation to the length of hospitalization for rehabilitation was not sufficient for the supplementation therapy to affect the outcome of rehabilitation. The interesting association of low folic acid levels with poor functional recovery after hip fracture may be linked, indirectly, to the association that has recently been found between risk for hip fracture and elevated homocysteine in older persons24 and the association between low levels of folic acid and elevated levels of homocysteine.25

The hemoglobin concentration at discharge was also found to have a significant effect on the results of rehabilitation, although this effect was identified only through secondary analyses of the results. The significance of this finding is that this variable has an effect on the results of rehabilitation but is less important than the 4 other modifiable factors that were identified in the primary study analyses. In rehabilitation of elderly patients, it is common clinical practice to correct anemia at the beginning of and throughout the rehabilitation process by transferring blood until a serum hemoglobin concentration of around 10mg/dL is achieved and by stimulating the blood marrow to continue correcting anemia by supplementation with iron and folic acid. It is possible that the finding on the effect of the hemoglobin concentration at discharge on the outcome of rehabilitation indicates a need to increase the hemoglobin concentration to an even higher level at the beginning of and throughout rehabilitation, but this issue should be addressed in a specifically designed study.

In addition to the list of variables that had an independent, significant association with the results of rehabilitation, the 32 variables that did not have an effect are noteworthy. Intuitively, some of those variables were expected to have a significant association, but the results of our study did not support these intuitions. The model that we used to analyze the results negates variables that affect another, more significant variable. This method of analysis led to the situation in which a relatively large number of specific diseases that are common in this age group, the total number of comorbid diseases, the GDS score, hypothyroidism, and a decreased serum vitamin B12 level that have a significant effect on the prefracture functional status were neutralized, in effect, by the recall FIM instrument, which had the most significant association with rehabilitation outcome. This result supports our contention, described previously, that the impaired functional state that stems from certain diseases, rather than the diseases per se, has the greatest association with the results of rehabilitation.

Apparently, the results of our study point to the possibility of improving rehabilitation outcome by therapeutic intervention in its early phases. The aim of this intervention should be to increase the serum albumin level by appropriate dietary adjustments and supplementation, to correct those visual defects that can be corrected such as prescription of suitable eyeglasses, to improve dyspnea by optimal treatment of the diseases that cause it, and to correct decreased serum folic acid levels by supplementation. However, the results of our study can only support an association and not causality between these 4 parameters and rehabilitation outcome. This situation prevents us from concluding that intervening with these factors may alter the outcome. The issue of causality should be investigated in interventional studies specifically designed to address this question.

The other 4 variables that were identified as having a significant association with rehabilitation outcome (prefracture functional state, mental status, age, prior stroke) cannot be changed by intervention during rehabilitation. However, the importance of these variables lies in their value as predictors of rehabilitation outcome. This assessment is important to help patients, families, and staff develop realistic expectations from the process and for directors of health care services for the elderly to reach reasonable decisions relating to rehabilitation strategies. Two of these 4 nonmodifiable variables (prefracture functional state, mental status) might be targets for rehabilitation in patients at high risk. Recipients of these interventions could benefit from such a preventive strategy. In relation to the variable of age, it should be noted that, although age was found to be a negative prognostic factor in this study, successful rehabilitation has been achieved in patients 85 years of age and above.26

Conclusions 

The outcome of rehabilitation of elderly patients after surgical repair of hip fracture is associated with 4 correctable clinical and nutritional parameters. The other 4 associated significant variables cannot be corrected but may help in predicting outcomes and adjusting expectations of all individuals involved in the rehabilitation process.

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