Relative and absolute test-retest reliabilities of biomechanical risk factors for knee osteoarthritis progression: benchmarks for meaningful change

OBJECTIVE

Biomechanical factors are important treatment targets in knee osteoarthritis. The knee adduction (KAM) and flexion (KFM) moments, quadriceps strength and power, load frequency, and body mass index (BMI) all have the potential to affect knee articular cartilage integrity by modulating forces across the joint. To identify clinically meaningful change, however, these measurements must be reliable and sensitive to change. This study estimated relative and absolute test-retest reliabilities over long periods of biomechanical risk factors for knee osteoarthritis progression.

METHOD

Data from a longitudinal, observational study were analyzed for knee osteoarthritis patients with data at baseline, 6-month and 24-month follow-ups. Gait kinematics and kinetics, quadriceps strength and power, daily load frequency and BMI were collected. Relative and absolute test-retest reliabilities of these measures were estimated using intraclass correlation coefficients (ICCs) and standard errors of measurement (SEMs), respectively. Minimal detectable change at the 95% confidence level (MDC95) was also calculated.

RESULTS

Data from 46 participants [36 women; age 61.0 (6.6) years] were included. Good-to-excellent relative reliabilities (ICC ≥ 0.80) indicated that KAM peak and impulse, quadriceps strength and power, and BMI had a strong ability to discriminate amongst participants. Absolute reliabilities were high for quadriceps strength and BMI, which demonstrated reasonable within-participant variability (SEMs ≤ 11% of the mean). The MDC95 values supported use of clinical interventions effective in reducing BMI and KAM, and increasing quadriceps strength.

CONCLUSION

These data are useful in interpreting findings from interventional or longitudinal investigations by determining whether observed changes are beyond measurement error and interpretable as true change.

Reliability and measurement error of the Osteoarthritis Research Society International (OARSI) recommended performance-based tests of physical function in people with hip and knee osteoarthritis

OBJECTIVE

To estimate the reliability and measurement error of performance-based tests of physical function recommended by the Osteoarthritis Research Society International (OARSI) in people with hip and/or knee osteoarthritis (OA).

DESIGN

Prospective repeated measures between independent raters within a session and within-rater over a week interval. Relative reliability was estimated for 51 people with hip and/or knee OA (mean age 64.5 years, standard deviation (SD) 6.21 years; 47% females; 36 (70%) primary knee OA) on the 30s Chair Stand Test (30sCST), 40m Fast-Paced Walk Test (40mFPWT), 11-Stair Climb Test (11-step SCT), Timed Up and Go (TUG), Six-Minute Walk Test (6MWT), 10m Fast-Paced Walk Test (10mFPWT) and 20s Stair Climb Test (20sSCT) using intra-class correlation coefficients (ICC). Absolute reliability was calculated using standard error of measurement (SEM) and minimal detectable change (MDC).

RESULTS

Measurement error was acceptable (SEM < 10%) for all tests. Between-rater reliability was: optimal (ICC > 0.9, lower 1-sided 95% CI > 0.7) for the 40mFPWT, 6MWT and 10mFPWT; sufficient (ICC >0.8, lower 1-sided 95% CI > 0.7) for 30sCST, 20sSCT; unacceptable (lower 1-side 95% CI < 0.7) for 11-step SCT and TUG. Within-rater reliability was optimal for 40mFPWT, and 6MWT; sufficient for 30sCST and 10mFPWT and unacceptable for 11-step SCT, TUG and 20sSCT.

CONCLUSIONS

The 30sCST, 40mFPWT, 6MWT and 10mFPWT, demonstrated, at minimum, acceptable levels of both between and within-rater reliability and measurement error. All tests demonstrated sufficiently small measurement error indicating they are adequate for measuring change over time in individuals with knee/hip OA.

Measurement properties of the WOMAC LK 3.1 pain scale

OBJECTIVE

The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) is applied extensively to patients with osteoarthritis of the hip or knee. Previous work has challenged the validity of its physical function scale however an extensive evaluation of its pain scale has not been reported. Our purpose was to estimate internal consistency, factorial validity, test-retest reliability, and the standard error of measurement (SEM) of the WOMAC LK 3.1 pain scale.

METHOD

Four hundred and seventy-four patients with osteoarthritis of the hip or knee awaiting arthroplasty were administered the WOMAC. Estimates of internal consistency (coefficient alpha), factorial validity (confirmatory factor analysis), and the SEM based on internal consistency (SEM(IC)) were obtained. Test-retest reliability [Type 2,1 intraclass correlation coefficients (ICC)] and a corresponding SEM(TRT) were estimated on a subsample of 36 patients.

RESULTS

Our estimates were: internal consistency alpha=0.84; SEM(IC)=1.48; Type 2,1 ICC=0.77; SEM(TRT)=1.69. Confirmatory factor analysis failed to support a single factor structure of the pain scale with uncorrelated error terms. Two comparable models provided excellent fit: (1) a model with correlated error terms between the walking and stairs items, and between night and sit items (chi2=0.18, P=0.98); (2) a two factor model with walking and stairs items loading on one factor, night and sit items loading on a second factor, and the standing item loading on both factors (chi2=0.18, P=0.98).

CONCLUSION

Our examination of the factorial structure of the WOMAC pain scale failed to support a single factor and internal consistency analysis yielded a coefficient less than optimal for individual patient use. An alternate strategy to summing the five-item responses when considering individual patient application would be to interpret item responses separately or to sum only those items which display homogeneity.

Protocol of the COSMIN study: COnsensus-based Standards for the selection of health Measurement INstruments

BACKGROUND

Choosing an adequate measurement instrument depends on the proposed use of the instrument, the concept to be measured, the measurement properties (e.g. internal consistency, reproducibility, content and construct validity, responsiveness, and interpretability), the requirements, the burden for subjects, and costs of the available instruments. As far as measurement properties are concerned, there are no sufficiently specific standards for the evaluation of measurement properties of instruments to measure health status, and also no explicit criteria for what constitutes good measurement properties. In this paper we describe the protocol for the COSMIN study, the objective of which is to develop a checklist that contains COnsensus-based Standards for the selection of health Measurement INstruments, including explicit criteria for satisfying these standards. We will focus on evaluative health related patient-reported outcomes (HR-PROs), i.e. patient-reported health measurement instruments used in a longitudinal design as an outcome measure, excluding health care related PROs, such as satisfaction with care or adherence. The COSMIN standards will be made available in the form of an easily applicable checklist.

METHOD

An international Delphi study will be performed to reach consensus on which and how measurement properties should be assessed, and on criteria for good measurement properties. Two sources of input will be used for the Delphi study: (1) a systematic review of properties, standards and criteria of measurement properties found in systematic reviews of measurement instruments, and (2) an additional literature search of methodological articles presenting a comprehensive checklist of standards and criteria. The Delphi study will consist of four (written) Delphi rounds, with approximately 30 expert panel members with different backgrounds in clinical medicine, biostatistics, psychology, and epidemiology. The final checklist will subsequently be field-tested by assessing the inter-rater reproducibility of the checklist.

DISCUSSION

Since the study will mainly be anonymous, problems that are commonly encountered in face-to-face group meetings, such as the dominance of certain persons in the communication process, will be avoided. By performing a Delphi study and involving many experts, the likelihood that the checklist will have sufficient credibility to be accepted and implemented will increase.

Analysis of a phosphorylcholine-based polymer coating on a coronary stent pre- and post-implantation

There has been a move towards surface treatments for metallic coronary stents in an effort to improve their compatibility within the body and to provide a vehicle for the delivery of therapeutics. The Biodiv Ysio range of stents is characterised by a biocompatible coating comprised of a crosslinked phosphorylcholine (PC)-based polymer. In addition to a review of some of the data collected to support safety and efficacy of this device, this paper also describes a number of techniques that have been employed to both visualise and quantify the coating on the stent. Explantation of both coated and uncoated stents from porcine coronary arteries revealed that both coated and uncoated stents were >90% endothelialised after 5 days. Typical histological analysis of stented vessel sections after 4 and 12 weeks implantation showed the presence of cell types characteristic of the inflammatory response associated with the trauma caused by stent placement, with no evidence for any additional coating-related adverse inflammatory sequelae. Finally, it was demonstrated by AFM and SEM that both the thickness and force required to remove the coating were essentially unchanged after 6 months implantation. Thus, both the long-term stability and relative biological inertness of the coating has been confirmed in vivo, supporting its use as a vehicle for local drug delivery.

A novel phosphorylcholine-coated contact lens for extended wear use

The preparation and characterisation of a new phosphorylcholine (PC)-coated silicone hydrogel contact lens for use in extended wear is described. The Michael-type addition of amines to acrylates forms the basis of the synthesis of a novel silicone-based macromer with hydrophilic functionality. It is demonstrated that this macromer can be combined with other silicone-based monomers, hydrophilic monomers and crosslinker to produce a contact lenses formulation. Examples of lenses with water contents of 33% and 46% are illustrated and their properties compared to other commercially available lenses. Materials with comparatively low modulus (<0.3 MPa) and adequate tear strength (>2-4MPa) with excellent elongation to break (>200%) can be obtained using this technology. In addition to the mechanical aspects. both the oxygen and solute permeabilities of the material can be controlled by the hydrophilic: hydrophobic monomer balance in the formulation. to obtain materials with attributes suitable for extended wear use. The PC coating is achieved by means of an in-mould coating (IMC) technique that produces a uniform and stable surface as determined by staining and XPS. The coating imparts both improved lens wettability (advancing contact angle of approximately 50 with virtually no hysteresis) and lower protein adsorption relative to the uncoated lens.

Phosphorylcholine-based polymer coatings for stent drug delivery

Phosphorylcholine-based polymers have been used commercially to improve the biocompatibility of coronary stents. In this study, one particular polymer is assessed for its suitability as a drug delivery vehicle. Membranes of the material are characterized in terms of water content and molecular weight cut-off, and the presence of hydrophilic and hydrophobic domains investigated by use of the hydrophobic probe pyrene. The in vitro loading and elution of a variety of drugs was assessed using stents coated with the polymer. The rate of a drug's release was shown not to be simply a function of its water solubility, but rather more closely related to the drug oil/water partition coefficient. This finding was explained in terms of the more hydrophobic drugs partitioning into, and interacting with, the hydrophobic domains of the polymer coating. The suitability of the coated stent as a drug delivery vehicle was assessed in vivo using a radiolabeled analog of one of the more rapidly eluting drugs, angiopeptin. Autoradiography showed that the drug was released locally to the wall of the stented artery, and could be detected up to 28 days after implantation.

Use of SF-36 and SF-12 health status measures: a quantitative comparison for groups versus individual patients

BACKGROUND

The extent to which SF-12 scores reflect SF-36 scores has not been well studied.

OBJECTIVES

One purpose was to compare the sensitivity to change of the SF-36 Physical Function sub-score, and the Physical Component Summary Scores (PCS) of the SF-36 and SF-12 on patients with low back pain (LBP). A second purpose was to determine if the SF-12 could serve as a surrogate measure for the SF-36 when making decisions about individual patients.

SUBJECTS

The sample consisted of 101 consecutive patients.

MEASURES

SF-36 questionnaires were completed by patients at both initial and discharge examinations. SF-12 scores were calculated from the completed SF-36 questionnaires. Therapists' judgments of whether patients were judged to have returned to premorbid function served as the construct for meaningful clinical change.

ANALYSIS

Receiver Operating Characteristic (ROC) curve analysis and repeated measures MANCOVA were used to assess sensitivity to change. Linear regression and 95% prediction bands described the extent to which SF-12 scores predict individual SF-36 scores.

RESULTS

No significant differences were found between the ROC curve areas for the Physical Function sub-scale, the PCS-36 and PCS-12. No significant differences were found for the comparison of change scores between PF-36, PCS-36 and PCS-12 scores.

CONCLUSION

The findings suggest that Physical Function sub-scores, SF-36 and SF-12 PCS scores are equally sensitive to change. SF-12 PCS scores do not adequately predict SF-36 PCS scores for individual patients. The PCS-12 should probably not be used to make judgments about the health status of individual patients with LBP.

Crosslinkable coatings from phosphorylcholine-based polymers

2-Methacryloyloxyethyl phosphorylcholine (MPC) was synthesised and then used in the preparation of crosslinked polymer membranes with lauryl methacrylate, hydroxypropyl methacrylate and trimethoxysilylpropyl methacrylate (crosslinker) comonomers. Some physical aspects of the membrane properties were evaluated in order to establish the basis for the synthesis of a series of post-crosslinkable polymers. These materials were made by copolymerisation of the constituent monomers via a free radical method, and characterised using NMR, FT-IR, viscometry and elemental analysis. The optimum crosslink density and conditions required for curing coatings of these polymers were investigated using atomic force microscopy (AFM) and showed the inclusion of 5 mol% silyl crosslinking agent to be ideal. A nanoindentation technique was employed to determine if the coating developed elasticity upon crosslinking. The biological properties of the coatings were evaluated using a variety of protein adsorption assays and blood contacting experiments, and an enzyme immunoassay was developed to detect E. coli in order to assess the level of bacterial adhesion to these biomaterials. Polymers of this type were shown to be very useful as coating materials for improving the biocompatibility of, or reducing the levels of adherent bacteria to medical devices.

Synthesis and characterisation of phosphorylcholine-based polymers useful for coating blood filtration devices

Copolymers of 2-methacryloyloxyethylphosphorylcholine (MPC) and lauryl methacrylate (LMA) of molar ratios MPC: LMAX where x = 1, 2 or 4, have been synthesised by two different free-radical polymerisation techniques. The solubility characteristics of the resulting materials were investigated in a variety of water: alcohol solvent mixtures and found to be influenced not only by the molar ratio of MPC: LMA, but also the method of synthesis. A window of solubility was observed for certain copolymers and the alcohol used in the solvent mixture was also found to have a profound influence on the solubility profile of the polymers. These materials were soluble in a wider range of aqueous methanol mixtures compared to aqueous mixtures of higher aliphatic alcohols, such as ethanol or isopropyl alcohol, which was rationalised in terms of the affinity of the phosphorylcholine headgroup for the various alcohols relative to water. 1H nuclear magnetic resonance spectroscopy was used to further examine the solution properties of the copolymers in various solvents. The copolymer MPC: LMA2 was coated onto a variety of substrates from both alcohol-only and water: alcohol solvent systems and the surface properties of the films compared by static and dynamic contact angle, atomic force microscopy (AFM) and attenuated internal reflectance Fourier transform infrared spectroscopy (ATR-IR). The coating formed from the water: alcohol solvent was found to be hydrophilic in nature, possessing spontaneous wettability, whereas films formed from alcohol-only solvents were hydrophobic, and only on conditioning with water were more wettable surfaces attained. This phenomenon was applied in the coating of leukocyte filtration material, where the aqueous-based systems demonstrated lower critical wetting surface tension (CWST) and shorter wetting times relative to both uncoated filters and those coated from alcohol-only systems. The haemocompatibility of the coated filters was equivalent for both coating solvent systems. employed, and far superior when compared to the uncoated control.

Development and initial validation of the back pain functional scale

STUDY DESIGN

A prospective repeated-measures design was applied.

OBJECTIVES

To examine the measurement properties of the Back Pain Functional Scale (BPFS) and the Roland-Morris Questionnaire (RMQ) and to formulate hypotheses and sample size estimates for a subsequent comparison study.

SUMMARY OF BACKGROUND DATA

Although there are numerous functional status measures for patients with low back pain, most have been conceived of and validated with a group rather than an individual patient as the unit of interest. Also, little has been done to formally compare-this includes the generation of a priori hypotheses, followed by statistical hypotheses testing-the many competing measures.

METHODS

Subjects were 77 patients with low back pain who were referred by physicians to 10 outpatient physical therapy clinics located in Canada and the United States. The questionnaires were administered at patients' initial visits, within 48 hours of the initial visit, and at 1-, 2-, and 3-week follow-up visits. Reliability, cross-sectional validity, and longitudinal validity (sensitivity to change) coefficients were calculated.

RESULTS

Test-retest reliability estimates of 0.81 and 0. 88 were obtained for the RMQ and BPFS, respectively. The measures demonstrated similar levels of cross-sectional validity. Correlations of 0.56 and 0.65 were noted between a prognostic rating of change and the RMQ and BPFS, respectively. The RMQ demonstrated a ceiling effect. Approximately 180 patients are needed for a subsequent head-to-head comparison study of the measures.

CONCLUSIONS

The BPFS appears to have sound measurement properties, and a formal head-to-head comparison study with the RMQ is warranted.

A comparison study of the back pain functional scale and Roland Morris Questionnaire. North American Orthopaedic Rehabilitation Research Network

OBJECTIVE

To determine whether the measurement properties of the Back Pain Functional Scale (BPFS) are superior to the Roland-Morris Questionnaire (RMQ).

METHODS

The BPFS and RMQ were administered on multiple occasions to 153 patients with low back pain attending physical therapy. Eleven Canadian clinics and 8 American clinics participated in the study. Ceiling effects, internal consistency, test-retest reliability, cross sectional discriminant validity, and sensitivity to change were investigated. Error estimates in scale points were obtained.

RESULTS

A ceiling effect was noted for 6 patients' RMQ scores compared to 3 patients' BPFS scores. Internal consistency for the RMQ and BPFS were 0.87 and 0.93, respectively. The error (95% CI) for a patient's score was +/- 15.5% of the scale range for the RMQ and +/- 10.5% for the BPFS. The test-retest reliability was 0.79 for the RMQ and 0.82 for the BPFS. The error associated with a patient's change score (95% CI) was 27.7% of the scale range for the RMQ and 22.2% for the BPFS. The measures showed similar levels of discriminant validity with respect to physical findings, work status, and education level. The BPFS was more adept at detecting different amounts of change in patients with back pain of less than 2 weeks' duration compared to patients with back pain of 2 or more weeks' duration.

CONCLUSION

The BPFS is a competitive functional status measure for patients with low back pain.

Interpreting validity indexes for diagnostic tests: an illustration using the Berg balance test

Physical therapists routinely make diagnostic and prognostic decisions in the course of patient care. The purpose of this clinical perspective is to illustrate what we believe is the optimal method for interpreting the results of studies that describe the diagnostic or prognostic accuracy of examination procedures. To illustrate our points, we chose the Berg Balance Test as an exemplar measure. We combined the data from 2 previously published research reports designed to determine the validity of the Berg Balance Test for predicting risk of falls among elderly people. We calculated the most common validity indexes, including sensitivity, specificity, predictive values, and likelihood ratios for the combined data. Clinical scenarios were used to demonstrate how we believe these validity indexes should be used to guide clinical decisions. We believe therapists should use validity indexes to decrease the uncertainty associated with diagnostic and prognostic decisions. More studies of the accuracy of diagnostic and prognostic tests used by physical therapists are urgently needed.

Applying the results of self-report measures to individual patients: an example using the Roland-Morris Questionnaire

Information concerning a patient's functional status is often obtained by asking the patient about activities that cannot be assessed directly in the clinical setting. This information is usually acquired through a verbal exchange between the clinician and patient. The measurement properties of the verbal exchange are unknown. An alternate method of obtaining this information is when patients self-report their functional status. The measurement properties of self-report questionnaires are well known; however, these measures are used infrequently for the evaluation of functional status, progress, and outcome in the clinic. Two reasons are possible for the infrequent use of self-report questionnaires: (1) values obtained from self-report measures have not been used to guide the care of the patient, and (2) a perception exists that these measures take a great deal of time to administer and score. The purpose of this clinical commentary was to describe the application, scoring, and use of a functional status measure (the Roland-Morris Questionnaire) for persons with low back pain and to illustrate how this questionnaire can be efficiently incorporated into clinical practice to aid decision making concerning individual patients. Three patient scenarios are used to illustrate the issues raised in this paper.

The prevalence of low back pain in adults: a methodological review of the literature

The prevalence of low back pain (LBP) has been reported in the literature for different populations. Methodological differences among studies and lack of methodological rigor have made it difficult to draw conclusions from these studies. A systematic review was done for adult community prevalence studies of LBP published from 1981 to 1998. The technique of capture-recapture was performed to estimate the completeness of the search strategy used. Established guidelines and a methodological scoring system were used to critically appraise the studies. Thirteen studies were deemed methodologically acceptable. Differences in the duration of LBP used in the studies appeared to affect the prevalence rates reported and explain much of the variation seen. It was estimated that the point prevalence rate in North America is 5.6%. Further studies using superior methods are needed, however, before this estimate can be used with confidence to make health care policies and decisions relating to physical therapy.

The Lower Extremity Functional Scale (LEFS): scale development, measurement properties, and clinical application. North American Orthopaedic Rehabilitation Research Network

BACKGROUND AND PURPOSE

The purpose of this study was to assess the reliability, construct validity, and sensitivity to change of the Lower Extremity Functional Scale (LEFS).

SUBJECTS AND METHODS

The LEFS was administered to 107 patients with lower-extremity musculoskeletal dysfunction referred to 12 outpatient physical therapy clinics.

METHODS

The LEFS was administered during the initial assessment, 24 to 48 hours following the initial assessment, and then at weekly intervals for 4 weeks. The SF-36 (acute version) was administered during the initial assessment and at weekly intervals. A type 2,1 intraclass correlation coefficient was used to estimate test-retest reliability. Pearson correlations and one-way analyses of variance were used to examine construct validity. Spearman rank-order correlation coefficients were used to examine the relationship between an independent prognostic rating of change for each patient and change in the LEFS and SF-36 scores.

RESULTS

Test-retest reliability of the LEFS scores was excellent (R = .94 [95% lower limit confidence interval (CI) = .89]). Correlations between the LEFS and the SF-36 physical function subscale and physical component score were r=.80 (95% lower limit CI = .73) and r = .64 (95% lower limit CI = .54), respectively. There was a higher correlation between the prognostic rating of change and the LEFS than between the prognostic rating of change and the SF-36 physical function score. The potential error associated with a score on the LEFS at a given point in time is +/-5.3 scale points (90% CI), the minimal detectable change is 9 scale points (90% CI), and the minimal clinically important difference is 9 scale points (90% CI).

CONCLUSION AND DISCUSSION

The LEFS is reliable, and construct validity was supported by comparison with the SF-36. The sensitivity to change of the LEFS was superior to that of the SF-36 in this population. The LEFS is efficient to administer and score and is applicable for research purposes and clinical decision making for individual patients.

Critical appraisal of the health research literature: prevalence or incidence of a health problem

This article identifies and discusses criteria that can be used by health professionals to critically appraise research articles that estimate the prevalence or incidence of a disease or health problem. These guidelines will help determine the validity and usefulness of such community assessment studies. The criteria relate to the validity of the study methods (design, sampling frame, sample size, outcome measures, measurement and response rate), interpretation of the results and applicability of the findings. The research question "What is the prevalence of dementia in Canada?" is used as an example for this paper.

Sensitivity to change of the Roland-Morris Back Pain Questionnaire: part 1

BACKGROUND AND PURPOSE

This study estimated the Roland-Morris Back Pain Questionnaire's (RMQ) change score that best classified patients as those who had achieved an important change and those who had not achieved an important change. The study also investigated whether the estimate of change was dependent on patients' initial scores.

SUBJECTS AND METHODS

The RMQ was administered to 226 patients with low back pain of less than 6 weeks' duration during their initial visit for physical therapy and following 3 to 6 weeks of treatment. A global rating of change was used to classify patients as those who had changed an important amount and those who had not changed. Receiver operating characteristic curves were used to identify the RMQ change score that most accurately classified patients with respect to important change. This analysis was repeated for 5 overlapping subsamples of patients with initial scores 0 to 8, 5 to 12, 9 to 16, 13 to 20, and 17 to 24.

RESULTS

The area under the receiver operating characteristic curves increased when patients' initial scores were taken into account. Estimates of important change were 2, 4, 5, 8, and 8 for the initial score intervals mentioned above.

CONCLUSION AND DISCUSSION

Important change appears to be dependent on patients' initial RMQ scores. Subsequent inquiry using different hypotheses would add support to the estimates of important change found in this study.

Sensitivity to change of the Roland-Morris Back Pain Questionnaire: part 2

BACKGROUND AND PURPOSE

One purpose of this study was to determine whether the Roland-Morris Back Pain Questionnaire (RMQ) could be used to detect clinically meaningful change in individual patients. The construct that served as the basis for this study was that RMQ change scores should be greater for patients meeting their treatment goals than for patients who did not meet their goals. The second purpose of the study was to determine whether sensitivity to change (STC) varies depending on the magnitude of the initial RMQ score.

SUBJECTS AND METHODS

Of the 143 patients with low back pain who completed the study, 104 patients achieved their goals and 39 patients did not achieve their goals. Receiver operating characteristic (ROC) curve analysis and likelihood ratios were used to determine the RMQ change scores that best classify patients as having met or not met their goals.

RESULTS

The area under the ROC curve for the entire RMQ scale was 0.68, while the curve areas for smaller RMQ intervals varied from 0.80 to 0.97.

CONCLUSION AND DISCUSSION

The STC for the entire RMQ scale was poor for the construct examined in this study. The likelihood ratios for smaller RMQ intervals support the construct validity of the RMQ for assessing change in disability. Initial RMQ score magnitudes must be taken into account to improve the rate of making correct predictions about whether meaningful change in disability will occur following treatment.

Comparison of two outcome measures for infants with cerebral palsy and infants with motor delays

BACKGROUND AND PURPOSE

The purpose of this study was to compare the Gross Motor Function Measure (GMFM) and the Peabody Developmental Gross Motor Scale (PDMS-GM) as measures of change in infants with cerebr-al palsy (CP) and infants with motor delays. We hypothesized that mean change scores would be greater for the GMFM than for the PDMS-GM.

SUBJECTS AND METHODS

Subjects were 42 infants with a mean adjusted age of 13.9 months (SD=6.1, range=4.2-24.2). Twenty-four infants had CP, and 18 infants had motor delays. The GMFM and the PDMS-GM were administered to the infants 3 times over a 6-month period. Raw scores were standardized for data analysis. Data were analyzed using a 3-factor repeated-measures analysis of variance.

RESULTS

For the 6-month period, mean PDMS-GM age-equivalent scores increased 3.8 months and mean scaled scores increased 35 points for infants with motor delays compared with increased scores of 1.8 months and 13 points for infants with CP. Mean GMFM scores increased by 12.2% for infants with rmotor delays and by 4.2% for infants with CP. The diagnosis X time interaction was significant. Infants with motor delays had a greater change in motor development compared with the infants with CP. The hypothesis that the GMFM is more responsive to change than the PDMS-GM was not supported.

CONCLUSION AND DISCUSSION

The findings suggest that the GMFM and the PDMS-GM are comparable in measuring change in infants with CP or motor delays. Implications for selection and use of either measure are discussed.

Use of generic versus region-specific functional status measures on patients with cervical spine disorders

BACKGROUND AND PURPOSE

Few data exist to support the use of functional status measures on patients with disorders of the cervical spine. This study was designed to compare the construct validity and sensitivity to change of the Neck Disability Index (NDI) and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36).

SUBJECTS AND METHODS

Patients (N = 146) with a variety of disorders of the cervical spine completed the NDI and the SF-36 prior to treatment. Following discharge from treatment, 69 of these patients completed a second NDI and SF-36.

RESULTS

There was evidence for the construct validity and sensitivity to change of the NDI and the physical and mental component scores of the SF-36. The ability of the NDI and SF-36 to detect change varied, depending on the construct tested. The SF-36 was superior in some instances, and the NDI was superior in other instances. The NDI appears to measure both mental and physical health-related factors.

CONCLUSION AND DISCUSSION

There appears to be substantial overlap between the 2 measures. The use of both measures, therefore, is probably not necessary. [Riddle DL, Stratford PW. Use of generic versus region-specific functional measures on patients with cervical spine disorders.

The patient-specific functional scale: validation of its use in persons with neck dysfunction

Self-report measures of disability are being used more frequently to assess patients' outcomes in clinical practice. This study examines the reliability, validity, and sensitivity to change of the Patient-Specific Functional Scale when applied to persons with neck dysfunction. The Patient-Specific Functional Scale and Neck Disability Index were applied at the initial visit, within 72 hours of the initial visit, and following 1-4 weeks of treatment in 31 patients with cervical dysfunction. At the time of the initial visit, the clinician made an estimate of patients' prognoses on a five-point scale. This estimate served as an priori construct for change: patients with better ratings would change more. The results demonstrate excellent reliability (R = .92) validity (r = .73-.83 compared with the Neck Disability Index, and r = .52-.64 compared with the prognosis rating), and sensitivity of change (r = .79-.83 compared with Neck Disability Index change scores, and r = .46-.53 compared with the prognosis rating). No difference was found between the Patient-Specific Functional Scale and Neck Disability Index in their ability to detect change over time. The results of this study are consistent with previous investigations which have concluded that the Patient-Specific Functional Scale is an efficient and valid measure for assessing disability and change in disability in persons with low back pain and knee dysfunction.

Measurement properties of the RM-18. A modified version of the Roland-Morris Disability Scale

STUDY DESIGN

This investigation had two components: one was an item analysis that examined data obtained at the initial patient assessment, and the second was a validation study that used a pretest-posttest design.

OBJECTIVES

The authors' goal, in this study, was to determine whether a shorter version of the Roland-Morris Questionnaire could be developed with measurement properties equal to or better than the original 24-item questionnaire.

SUMMARY OF BACKGROUND DATA

The measurement properties of the Roland-Morris Questionnaire have been shown to be better than or equal to competing measures. A number of studies have reported modified versions of the Roland-Morris without providing the measurement properties of the modified tool.

METHODS

The item analysis investigated endorsement frequency, interitem correlations, item-corrected item total correlations, and coefficient alpha with various combinations of items deleted. The validation study examined reliability, concurrent validity, and longitudinal validity (sensitivity to change). The analyses included comparisons with the Oswestry and Jan van Breeman Pain Questionnaires.

RESULTS

The item analysis suggested than six items could be detected from the Roland-Morris Questionnaire. The validation study demonstrated that the shorter version, named the RM-18, has measurement properties that are equal to those of the longer version.

CONCLUSIONS

The RM-18 can be used as an outcome measure in clinical trials or as a tool to aid in decision making concerning individual patients. In either case, its measurement properties are equal to those of the 24-item Roland-Morris Questionnaire.

The Patient-Specific Functional Scale: measurement properties in patients with knee dysfunction

BACKGROUND AND PURPOSE

Assessing disability is important, and numerous interviewer-assisted and self-report questionnaires are used to accomplish this task. These questionnaires can be classified as being generic, condition or disease specific, or patient specific. The purpose of this study was to determine test-retest reliability, construct validity, and sensitivity to change of the Patient-Specific Functional Scale (PSFS) when applied to patients with knee dysfunction.

SUBJECTS

Subjects were 38 physician-referred patients with knee dysfunction.

METHODS

The PSFS and the Medical Outcomes Study 36-Item Short-Form Health Survey were administered at a patient's initial visit and following 2 to 3 weeks of treatment. An assessment of global change was also made by the patient and clinician at follow-up. These measures allowed the assessment of construct validity and sensitivity to change. To obtain an estimate of reliability, the PSFS was also administered within 72 hours of the initial assessment.

RESULTS

Test-retest reliability and sensitivity to change were excellent (intraclass correlation coefficient [type 2,1] R = .84 and Pearson's r = .78, respectively). Validity was also confirmed.

CONCLUSION AND DISCUSSION

Previous investigation on persons with low back pain suggested that the PSFS has promising measurement properties. The results of this study provide further evidence supporting the reliability, validity, and efficiency of the PSFS. Further investigation is needed to determine the extent to which the PSFS can be applied across a variety of conditions and age groups.

Use of the standard error as a reliability index of interest: an applied example using elbow flexor strength data

The intraclass correlation coefficient (ICC) and the standard error of measurement (SEM) are two reliability coefficients that are reported frequently. Both measures are related; however, they define distinctly different properties. The magnitude of the ICC defines a measure's ability to discriminate among subjects, and the SEM quantifies error in the same units as the original measurement. Most of the statistical methodology addressing reliability presented in the physical therapy literature (eg, point and interval estimations, sample size calculations) focuses on the ICC. Using actual elbow flexor make and break strength measurements, this article illustrates a method for estimating a confidence interval for the SEM, shows how an a priori specification of confidence interval width can be used to estimate sample size, and provides several approaches for comparing error variances (and square root of the error variance, or the SEM).

Phosphorylcholine coating of ePTFE grafts reduces neointimal hyperplasia in canine model

This study attempts to prevent neointimal hyperplasia by coating the graft luminal surface with a derivative of phosphorylcholine (PC), thereby providing a biocompatible surface with the assumption of limiting pannus tissue ingrowth from the graft anastomoses. Bilateral carotid artery bypass grafts were placed in six dogs using expanded polytetrafluoroethylene (ePTFE). In each animal, one carotid arterial-arterial conduit was constructed using a graft having a PC coating over the entire luminal surface of the graft. On the contralateral side, uncoated graft served as a control. The processed specimens were analyzed for graft neointimal area and neointimal thickness. Cell proliferation was assessed by staining for bromodeoxyuridine (BrdU) incorporation. All grafts were patent except one control graft that was occluded at 4 weeks. There was a significant reduction in the anastomotic graft neointimal area between the treated and control groups (0.27 +/- 0.17 mm2 versus 0.53 +/- 0.13 mm2, respectively; p = 0.008). Furthermore, the BrdU labeling index in the graft neointimal tissues was significantly smaller (p < 0.001) in the treated group (2.64 +/- 0.77%) as compared with the control group (5.07 +/- 0.83%). These data demonstrate that PC coating of ePTFE significantly reduces graft neointimal hyperplasia and cell proliferation in a canine carotid artery bypass model. The application of PC within the ePTFE graft effectively blocks tissue ingrowth from the adjacent native vessel, thereby preserving the anastomosis luminal diameter.

Health status measures: strategies and analytic methods for assessing change scores

Over the last 15 years, numerous self-report health status measures have appeared in the literature. An important parallel development has been the development of numerous strategies for assessing change in health status over time. The purpose of this article is to summarize and critique the more common design and analytic strategies for assessing the meaningfulness of change over time. Five commonly reported designs are presented, critiqued, and depicted using examples from the literature. Methods for analyzing results are reviewed and illustrated using two data sets. Insights into comparing competing health status measures are provided. In summary, the article suggests that some designs and analytic strategies are more adept than others at assessing change and that these methods should be considered when planning sensitivity-to-change studies.

Defining the minimum level of detectable change for the Roland-Morris questionnaire

BACKGROUND AND PURPOSE

The Roland-Morris Questionnaire (RMQ) is a self-administered disability measure in which greater levels of disability are reflected by higher numbers on a 24-point scale. The RMQ has been shown to yield reliable measurements, which are valid for inferring the level of disability, and to be sensitive to change over time for groups of patients with low back pain. Little is known about the usefulness of this instrument in aiding decision making regarding individual patients. The purpose of this study was to determine the minimum level of detectable change when the RMQ is applied to individual patients.

SUBJECTS

The study sample consisted of 60 outpatients with low back pain.

METHODS

The RMQ was administered at the subjects' initial visit and again 4 to 6 weeks later. Conditional standard errors of measurement (CSEMs) were computed for initial and follow-up RMQ scores, and these values were used to estimate the minimum level of detectable change. Results. Minimum levels of detectable change at the 90% confidence level varied from 4 to 5 RMQ points.

CONCLUSION AND DISCUSSION

The magnitude of CSEMs is sufficiently small to detect change in patients with initial scores in the central portion of the scale (4-20 RMQ points); however, the magnitude is too large to detect improvement in patients with scores of less than 4 and deterioration in patients who have scores greater than 20.

A review of the McMurray test: definition, interpretation, and clinical usefulness

Clinicians frequently use the results of clinical diagnostic tests to make decisions concerning patients. The intent of this paper is to review the technical aspects and measurement properties of the McMurray test and, more globally, to illustrate the impact that indiscriminate test application has on test interpretation. The literature shows that diagnostic accuracy studies, which evaluate the test described by McMurray, yield remarkably similar estimates of sensitivity (about 26%) and specificity (about 94%). These test characteristics are applied to three case scenarios to illustrate the impact that history-specific prevalence (i.e., the likelihood a patient has the condition based on the history) has on the predictive values. The results show a high false positive rate when applied to patients who, based on the history, have a low pre-physical examination likelihood for the condition of interest and a higher false negative rate when applied to patients who have a high history-specific prevalence. Readers are warned that the exhaustive examination approach effectively lowers the prevalence and results in a high false positive rate. The impact that the exhaustive approach has on increasing the false positive rate is universal to all diagnostic investigations and is not unique to the McMurray test.

Interrater reliability of lumbar accessory motion mobility testing

BACKGROUND AND PURPOSE

This study examined the interrater agreement, or reliability, of accessory motion mobility testing of the lumbar spine in patients with low back pain.

SUBJECTS

Subjects were 18 patients with low back pain referred to the physical therapy outpatient department of a university teaching hospital.

METHODS

Six orthopedic physical therapists evaluated the posterior-anterior (P-A) accessory motion mobility at each of six levels, L-1 to the sacral base, on each subject. The mobility was recorded on a nine-point scale, and reproduction of pain was noted. The physical therapists noted any level at which mobility or pain findings were of significance to treat. To evaluate agreement on the identification of spinal levels, therapists were asked to identify one spinous process, which was arbitrarily marked on each subject. Kappa analyses and intraclass correlation coefficients (ICCs) were calculated to evaluate agreement on the level of the marked segment and the mobility at that level, respectively.

RESULTS

The ICC for determination of the marked level was R(2,1) = .69 (95% confidence interval = .53-.82). The ICC for mobility findings at the marked level was R(2,1) = .25 (95% confidence interval = 0-.44). A secondary Kappa analysis to determine agreement on treatment decision making demonstrated similarly low levels of agreement.

CONCLUSION AND DISCUSSION

There is poor interrater agreement on determination of the segmental level of a marked spinous process. There is poor interrater reliability of P-A accessory mobility testing in the absence of corroborating clinical data. Caution should be exercised when physical therapists make clinical decisions related to the evaluation of motion at a specific spinal level using P-A accessory motion testing.

Biocompatible surfaces using methacryloylphosphorylcholine laurylmethacrylate copolymer

Many materials used in the medical device industry were not originally developed for these applications. In general, these materials elicit adverse biologic responses when in contact with body fluids such as blood, and the mechanisms of the response of blood to an artificial surface are well characterized. Protein adsorption, platelet adhesion, and activation of the coagulation pathway can subsequently lead to thrombus formation with grave clinical consequences in the absence of anticoagulant. However, the use of anticoagulants can result in complications. In recent years various approaches for overcoming these problems by improvement of the biocompatibility of materials have been advocated. One approach is that of biomembrane mimicry, whereby the surface of a material is coated with a derivative of phosphorylcholine (PC). PC is the major lipid head group component found in the outer surface of biologic cell membranes. In this paper, the application of PC coatings to a range of materials is discussed together with characterization of the surfaces using in vitro biocompatibility tests. Studies of fibrinogen and platelet binding have shown significant reductions in adsorption of these components to various PC coated materials relative to uncoated controls. Materials tested, amongst others, include PVC, polyethylene, polycarbonate, and nylon. The stability of the PC coatings has been studied using radiolabeled derivatives. Results using several materials show that physiadsorbed PC coatings are extremely stable, thus making the coatings suitable for use in a wide variety of medical applications. Extensive biologic evaluations to assess the toxicologic profile of PC derivatives and coated devices have also been carried out and in all tests the materials have been shown to be nontoxic, thus making them suitable for human use. Ex vivo animal and human studies performed support the in vitro data.

Assessing change over time in patients with low back pain

BACKGROUND AND PURPOSE

This study compared the ability of the Roland-Morris (RM), Oswestry (OSW), and Jan van Breemen Institute (JVB) pain and function questionnaires to detect change over time.

SUBJECTS

The sample consisted of 88 patients with mechanical low back pain who were referred by physicians to the outpatient physical therapy department of a teaching hospital.

METHODS

Questionnaires were completed by the subjects at their initial visit and 4 to 6 weeks later. Clinically important change was estimated by having the subject and the clinician independently complete two rating scales. Sensitivity to change was assessed using receiver operating characteristic (ROC) curve analysis.

RESULTS

The ROC curve areas for the RM (0.79), OSW (0.78), and JVB pain (0.79) questionnaires were significantly greater than for the JVB function questionnaire (0.66). Blank and multiple responses per item were present on approximately 20% of the OSW questionnaires and 14% of the JVB questionnaires. Words rather than checks were evident on 3% of the RM questionnaires.

CONCLUSION AND DISCUSSION

Based on the latter finding, we believe the RM questionnaire may be the preferred instrument for assessing change over time in patients with low back pain.

A comparison of make and break tests using a hand-held dynamometer and the Kin-Com

The assessment of muscle strength is a task performed frequently by physical therapists. The purposes of this study were to determine whether intrasession test-retest reliability differs between make and break tests and strength tests that do not require an assessor (eg., isometric Kin-Com test) and hand-held dynamometer (HHD) assessments. The elbow flexor strength of 32 healthy, female volunteers was measured under four test conditions: Kin-Com make and break, and HHD make and break. Two measurements were performed for each test condition by the same rater. The results showed: 1) measurements obtained using the HHD deviated from a normal distribution, 2) comparable reliability coefficients for the make and break tests were obtained from the Kin-Com device, 3) there was a higher reliability coefficient for the make test compared with the break test for the HHD tests, and 4) the measured forces for the break tests were higher than the make tests. The results support the premise that hand-held dynamometry is a viable alternative to more costly modes of isometric strength measurements, provided the assessor's strength is greater than that of the specific muscle group being measured.

Reliability of the Fugl-Meyer assessment for testing motor performance in patients following stroke

BACKGROUND AND PURPOSE

The purpose of this study was to establish the interrater reliability of assessments made with the Fugl-Meyer evaluation of physical performance in a rehabilitation setting.

SUBJECTS

Twelve patients (7 male, 5 female), aged 49 to 86 years (mean = 66), who had sustained a cerebrovascular accident participated in the study. All patients were admitted consecutively to a rehabilitation center and were between 6 days and 6 months poststroke.

METHODS

Three physical therapists, each with more than 10 years of experience, assessed the patients in a randomized and balanced order using this assessment. The therapists standardized the assessment approach prior to the study but did not discuss the procedure once the study began.

RESULTS

The overall reliability was high (overall intraclass correlation coefficient = .96), and the intraclass correlation coefficients for the subsections of the assessment varied from .61 for pain to .97 for the upper extremity.

CONCLUSION AND DISCUSSION

The relative merits of using the Fugl-Meyer assessment as a research tool versus a clinical assessment for stroke are discussed.

Grading written essays: a reliability study

The purpose of this study was to examine the interrater reliability of grades obtained by physical therapy and occupational therapy tutors in rating their students' term papers. This study was carried out in two phases. In phase 1, four student essay papers (two physical therapy students' papers and two occupational therapy students' papers) with grades that had been assigned from the previous year's course were randomly selected from a bank of papers. These papers were independently rated by three course planners (who were responsible for planning, coordinating, and tutoring in the course), and agreement as to the assignment of grades for each paper was established. In phase 2, the same students' essays were rated independently by eight course tutors. To test for differences among students' written essay papers and for differences among the raters in the subcategories of discipline (physical therapy versus occupational therapy) and level of expertise (novice versus experienced) in grading essays, a three-way analysis of variance was performed. An intraclass correlation coefficient (ICC) was calculated for interrater reliability. Although there were no statistically significant differences among the tutors with regard to their discipline and expertise, the reliability analysis produced an ICC of .79. Strategies to enhance the reliability of grading essays are discussed.

Effect of station examination item sampling on generalizability of student performance

This article may be of interest to physical therapy educators who are responsible for structuring station or practical examinations used to evaluate physical therapy students. The global intent of the article is to provide information that may be useful in selecting test items. Specifically, the purposes of this study were 1) to examine how two item-sampling strategies (one based on different diagnostic concepts, or diagnostic probes, and the other based on different anatomical sites) influenced the generalizability of a station examination, 2) to determine the interrater reliability during the station examination, and 3) to determine whether the status of the rater (that of observer or simulated patient) influenced the rating. Using a nested study design, 24 physical therapy students were assessed by eight raters. The raters were randomly and equally assigned to four teams. Each team assessed six students. One rater acted as the simulated patient for the first three students in each group, and the other rater acted as observer. This order was reversed for the last three students. Each student performed nine mini-diagnostic patient cases consisting of three diagnostic probes reproduced at three different anatomical sites. The results demonstrate that 1) similar diagnostic concepts can be generalized across anatomical sites, although different concepts or skills cannot be generalized at a given anatomical site or across sites; 2) interrater reliability was excellent; and 3) the status of the raters (ie, simulated patient or observer) did not bias the ratings.(ABSTRACT TRUNCATED AT 250 WORDS)

Generalizability of grip strength measurements in patients with tennis elbow

The purpose of this study was to determine the interrepetition and interoccasion generalizability of grip strength measurements in patients with the diagnosis of proximal extensor carpi radialis brevis tendinitis. Thirty-five consecutive patients (mean age = 44.5 +/- 8.6 years; mean duration of symptoms = 3.9 +/- 3.5 months) fulfilling the eligibility criteria participated in the study. Measurements of pain-free grip strength and maximum grip strength for the involved limb and maximum grip strength for the uninvolved limb were taken on two test dates within seven days of each other. We calculated the variation between measurements within a test session and the variation from one session to the next using generalizability coefficients based on the mean of the six measurements. The coefficients for interrepetition, interoccasion, and overall generalizability were .99, .97, and .96, respectively. The clinical implication of these findings is that the overall generalizability can best be enhanced by averaging grip strength measurements recorded from multiple test sessions rather than by increasing the number of repetitions during a single test session.

Efficiency analysis of two written short-answer student evaluation formats

The purpose of this study was to compare the efficiency of two written short-answer student evaluation formats. Efficiency was defined in this study as reliability per unit of examination time. Twenty second-year physical therapy students enrolled in the soft tissue injuries portion of the orthopedic course completed a 12-item quiz consisting of two formats (diagnosis and response set) with six parallel content items per format. The outcome measures of interest were 1) students' score, 2) amount of time required to complete each item, and 3) amount of time required by the faculty members to grade each item. The results indicated that a greater reliability per unit of examination time was achieved for the diagnosis format than for the response set format and that the diagnosis format could be graded more rapidly and with a higher level of interrater agreement than the response set format. Students' grades on the diagnosis format items tended to be higher (although not statistically significant) than the grades on the response set format items, suggesting that when a criterion-referenced system is used, the minimal acceptable baseline score should be raised when using the diagnosis format. Further study is required to evaluate the validity of the diagnosis format.