Findings from this study indicated there was a mobility advantage at 2 months post-hip fracture for patients who received more PT between the day of hip fracture surgery and the first 3 PODs. But the association between early PT and mobility was attenuated at 6 months postfracture. Thus, even with the average 6-day length of stay for hip fracture in this sample, those who received a few days of hospital PT had better mobility, at least in the early postacute period.
These findings are consistent with those of other studies, which found that more PT sessions in the hospital were associated with better early mobility (at time of hospital discharge).7–9
Moreover, they match other findings of no mobility differences at later time points.7,11
To evaluate the clinical significance of the finding that more early PT increased mobility at 2 months, the expected 2-month score was estimated for the average patient (i.e., the patient with mean scores for all the predictor variables except early PT sessions) who received one session compared with three sessions of early PT. The mobility scores were 6.5 versus 7.2, respectively, a difference of 0.7 on the 14-point mobility scale. Consider that a 1-point difference would be equivalent to the patient needing some hands-on human assistance with mobility versus needing only supervision.
The importance of the early PT finding was also evaluated by examining the parameter estimate from the 2-month regression using the FIM locomotion score transformed to the probability of independent mobility (walking 150 feet and climbing stairs without human help) at 6 months. The parameter estimate for early PT indicated that each additional early PT session increased the chances of future independent mobility 2%. Consequently, having three to four postoperative PT sessions increased patients’ chances of independent mobility at 2 months 6% to 8%, all else being equal, over those of patients who did not receive early PT sessions.
The finding that later therapy was not associated with mobility at 2 or 6 months is noteworthy. Fifty-five percent of patients were still receiving therapy 7 weeks after the surgery, and most of it was in post-acute care facilities or at home under the Medicare skilled home health benefit. It is possible that, if skilled care providers saw weak or ambiguous evidence of functional improvement, they continued the therapy up to the maximum amount covered by insurance. If so, duration may be more sensitive to provider reimbursement than to patient outcomes, and this would tend to weaken the relationship between therapy and mobility at later time periods.
The possibility that later therapy moderated the relationship between early PT and mobility or vice versa was considered. In particular, was the early PT relationship weaker for patients who received none or a small amount of later therapy? Or conversely, was later therapy in the absence of early PT too little therapy, too late in the postoperative trajectory to influence 2- and 6-month mobility? The potential interaction of early PT and later therapy was modeled with a product term (early PT measured as 1 or 0 multiplied by the number of therapy sessions from POD4 to week 4) in the regressions of 2- and 6-month mobility on the variables included in , but the interaction term was not significantly different from zero in either model. Thus, early PT mattered, but later therapy did not matter irrespective of whether the patient had early PT. However, the nonsignificant findings for posthospital therapy should also be considered in light of the less accurate and complete measurement of it compared with early PT.
This study has other limitations. It was observational and relied on information about the number and timing of therapy sessions as part of usual care after hip fracture. It is possible that patient receipt of early PT was associated with unmeasured factors related to mobility or rehabilitation prognosis. For example, patients who were expected to recover may have been more likely to receive early PT and conversely, those with a more limited rehabilitation prognosis may not have received early PT. The patients selected for early PT may have improved by 2 months with or without it. Thus, these results may overestimate the relationship between PT and mobility. However, the analysis tried to minimize bias by controlling for factors affecting prognosis, including measures of mobility before the fracture, comorbidity, severity of illness, and new impairments during the hospitalization.
Although this study controlled for patient characteristics at baseline and discharge, the progress patients made during the postacute rehabilitation process was not measured or controlled for. Thus, although there were good control variables for early PT and therapy effects in the first 4 weeks, this is less true for Weeks 4 to 8 because patient characteristics were not measured again at 4 weeks postfracture.
Another limitation arises from the use of the FIM. In particular, the FIM locomotion subscale measures independence in terms of the amount of assistance patients receive from a person or device to walk and climb stairs. If PT were to improve a patient’s gait speed or reduce their fear of falling, these changes might not be directly reflected in the FIM score, but these changes and others, such as less perceived exertion, are aspects of mobility that are important to patients, families, and clinicians.
There is a complex interplay among pain, delirium, and PT in the first few PODs.21–23
Patients with inadequately treated pain may be more likely to refuse or not be offered early PT. At the same time, patients may experience pain after early PT and be more likely to miss the next scheduled session. Moreover, undertreated perioperative pain significantly increases the risk for developing delirium,23
which itself may interfere with early PT. However, these data do not allow us to disentangle these relationships. What seems clear is that the benefits of early PT are more likely to be realized if patients’ pain is managed.
As is true of other longitudinal studies of clinically important conditions associated with high mortality (e.g., hip fracture, cancer, stroke), the analysis reported here was based on a sample of survivors who may have been healthier than the full sample at baseline (including patients who died between discharge and 6-month interview) but could not have been identified prospectively. However, as noted earlier, when the FIM locomotion score (range 2–14) was transformed such that each score represented the chances of future independent mobility (which was 0 for patients who died), the positive relationship between early PT and 2-month mobility and the lack of a relationship at 6 months remained despite including data for patients who died. Also, the lack of a relationship between later therapy and 2- and 6-month mobility persisted using the transformed variable and including patients who died.
As with all observational studies of PT, it was not possible to isolate the role of PT from that of other care received after hip fracture, and like other observational studies, this one lacks detailed information on the timing, intensity, and frequency of PT during hospitalization and postdischarge. Given that PT after hip fracture is standard practice for most patients, well-designed randomized, controlled trials of the effect of varying schedules and amounts of PT on functional status after hip fracture would be informative.
In conclusion, PT immediately after hip fracture surgery was associated with better mobility at 2 months, but the positive relationship was attenuated by 6 months postfracture. Later therapy, from POD4 through 8 weeks postfracture, was not related to 2- and 6-month mobility.
The number of therapy sessions is but one part of the rehabilitative and overall package of services received by patients with hip fracture. In the therapy, little is known about how the timing and intensity of therapy sessions might affect the outcomes. Moreover, reimbursement policy, rather than clinical judgment or evidence of effectiveness, may largely dictate prescription of timing and intensity. Additionally, apart from the therapy sessions, the timing of surgery,9,24–26
management of pain,27
and appropriate nutrition may also affect outcomes.28
Other studies are needed to determine the magnitude and duration of the benefit from PT sessions if other aspects of care were optimized. In the meantime, early mobilization and PT sessions are prudent for patients undergoing surgical repair after fracture of a hip.