Original article
Performance-Based or Self-Report Measures of Physical Function: Which Should Be Used in Clinical Trials of Hip Fracture Patients?

Presented as an abstract to the American Congress of Rehabilitation Medicine, October 3–7, 2007, Washington DC, and to the Gerontological Society of America, November 17, 2007.
https://doi.org/10.1016/j.apmr.2008.04.016Get rights and content

Abstract

Latham NK, Mehta V, Nguyen AM, Jette AM, Olarsch S, Papanicolaou D, Chandler J. Performance-based or self-report measures of physical function: which should be used in clinical trials of hip fracture patients?

Objectives

To assess the validity, sensitivity to change, and responsiveness of 3 self-report and 4 performance-based measures of physical function: activity measure for postacute care (AM-PAC) Physical Mobility and Personal Care scales, the Medical Outcomes Study 36-Item Short Form Health Survey Physical Function scale (SF-36 PF), the Physical Functional Performance test (PFP-10), the Short Physical Performance Battery (SPPB), a 4-meter gait speed, and the six-minute walk test (6MWT).

Design

A prospective observational study of patients after a hip fracture. Assessments were performed at baseline and 12 weeks postenrollment.

Setting

Inpatient and outpatient rehabilitation facilities in Norway, the United Kingdom, Sweden, Israel, Germany, the United States, Denmark, and Spain.

Participants

A sample of study participants (N=108) who had a hip fracture.

Interventions

Not applicable.

Main Outcome Measures

Assessments of validity (known-groups, concurrent, construct, and predictive), sensitivity to change (effect size, standardized response mean [SRM], SE of measure, minimal detectable change (MDC), and responsiveness (optimal operating cut-points and area under the curve) between baseline and 12-week follow-up.

Results

All physical function measures achieved comparably acceptable levels of validity. Odds ratios in predicting patient Global Assessment of Improvement at 12 weeks were as follows: AM-PAC Physical Mobility scale, 5.3; AM-PAC Personal Care scale, 3.6; SF-36 PF, 4.3; SPPB, 2.0; PFP-10, 2.5; gait speed, 1.9; and 6MWT, 2.4. Effect sizes and SRM exceeded 1 SD for all 7 measures. Percent of patients who exceeded the MDC90 at week 12 were as follows: AM-PAC Physical Mobility scale, 90%; AM-PAC Personal Care scale, 74%; SF-36 PF, 66%; SPPB, 36%; PFP-10, 75%; gait speed, 69%; and 6MWT, 75%. When evaluating responsiveness using the area under receiver operating curves for each measure, all measures had acceptable responsiveness, and no pattern emerged of superior responsiveness depending on the type of measure used.

Conclusions

Findings reveal that the validity, sensitivity, and responsiveness of self-report measures of physical function are comparable to performance-based measures in a sample of patients followed after fracturing a hip. From a psychometric perspective, either type of functional measure would be suitable for use in clinical trials where improvement in function is an endpoint of interest. The selection of the most appropriate type of functional measure as the primary endpoint for a clinical trial will depend on other factors, such as the measure's feasibility or the strength of the association between the hypothesized mechanism of action of the study intervention and a functional outcome measure.

Section snippets

Subjects

Data used for these analyses were obtained from a 24-week, randomized, double-blind, placebo-controlled, multicenter study of an investigational drug to treat muscle wasting among patients recovering from a unilateral hip fracture with noncomplicated surgical repair. The patients were age 65 years or older (men or women), within 17 days of surgical repair of a unilateral hip fracture, and at least partially weight-bearing. Surgical repair occurred no more than 4 days posthip fracture. Prior to

Results

Table 1 shows descriptive statistics of the sample at baseline and week 12. At week 12, there were 26 patients (24.1%) lost to follow-up. The mean age of the sample ± SD (N=108) was 79.4±8.0, with approximately 75% (n=79) women. For all performance and self-report measures, the mean and median scores increased significantly from baseline to week 12.

Discussion

The main finding of this study is that the validity, sensitivity to change, and responsiveness of self-report and performance-based measures of physical function are comparable in a sample of patients with recent hip fracture.

Consistent with previous studies, all measures included in this study of patients recovering from hip fracture had a high degree of concurrent, known-groups, construct, and predictive validity as measures of physical function. When concurrent validity was assessed, all

Conclusions

This study did not support prior findings that performance-based measures of physical function have superior psychometric properties when compared with self-report measures of physical function, and, in particular, did not find evidence that performance measures have superior sensitivity to change. Both measurement approaches (self-report and performance-based) produced similar and acceptable results in terms of validity, sensitivity to change, and responsiveness.

Because the psychometric

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  • Cited by (0)

    Supported by Merck and Co.

    A commercial party having a direct financial interest in the results of the research supporting this article has conferred or will confer a financial benefit on the author or one or more of the authors. Jette has stock interests in CRE Care, LLC, which distributes the activity measure for postacute care products.

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