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Biomedical subjects

Paul W Stratford

Publications and source records attributed to Paul W Stratford.

At least 19 recordsLinked to original sources
PubMed2006

Modeling early recovery of physical function following hip and knee arthroplasty.

BACKGROUND: Information on early recovery after arthroplasty is needed to help benchmark progress and make appropriate decisions concerning patient rehabilitation needs. The purpose of this study was to model early recovery of physical function in patients undergoing total hip (THA) and knee (TKA) arthroplasty, using physical performance and self-report measures. METHODS: A sample of convenience of 152 subjects completed testing, of which 69 (mean age: 66.77 +/- 8.23 years) underwent THA and 83 (mean age: 60.25 +/- 11.19 years) TKA. Postoperatively, patients were treated using standardized care pathways and rehabilitation protocols. Using a repeated measures design, patients were assessed at multiple time points over the first four postoperative months. Outcome measures included the Lower Extremity Function Scale (LEFS), the physical function subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC PF), the 6 minute walk test (6 MWT), timed up and go test (TUG) and a timed stair test (ST). Average recovery curves for each of the measures were characterized using hierarchical linear modeling. Predictors of recovery were sequentially modeled after validation of the basic developmental models. RESULTS: Slopes of recovery were greater in the first 6 to 9 weeks with a second-degree polynomial growth term (weeks squared) providing a reasonable fit for the data over the study interval. Different patterns of recovery were observed between the self-report measures of physical function and the performance measures. In contrast to the models for the WOMAC PF and the LEFS, site of arthroplasty was a significant predictor (p = 0.001) in all of the physical performance measure models with the patients post TKA initially demonstrating higher function. Site of arthroplasty (p = 0.025) also predicted the rate of change for patients post THA and between 9 to 11 weeks after surgery, the THA group surpassed the function of the patients post TKA. CONCLUSION: Knowledge about the predicted growth curves will assist clinicians in referencing patient progress, and determining the critical time points for measuring change. The study has contributed further evidence to highlight the benefit of using physical performance measures to learn about the patients' actual level of disability.

Aged↗
PubMed2006

Simulated computerized adaptive test for patients with lumbar spine impairments was efficient and produced valid measures of function.

OBJECTIVE: To equate physical functioning (PF) items with Back Pain Functional Scale (BPFS) items, develop a computerized adaptive test (CAT) designed to assess lumbar spine functional status (LFS) in people with lumbar spine impairments, and compare discriminant validity of LFS measures (theta(IRT)) generated using all items analyzed with a rating scale Item Response Theory model (RSM) and measures generated using the simulated CAT (theta(CAT)). METHODS: We performed a secondary analysis of retrospective intake rehabilitation data. RESULTS: Unidimensionality and local independence of 25 BPFS and PF items were supported. Differential item functioning was negligible for levels of symptom acuity, gender, age, and surgical history. The RSM fit the data well. A lumbar spine specific CAT was developed that was 72% more efficient than using all 25 items to estimate LFS measures. theta(IRT) and theta(CAT) measures did not discriminate patients by symptom acuity, age, or gender, but discriminated patients by surgical history in similar clinically logical ways. theta(CAT) measures were as precise as theta(IRT) measures. CONCLUSION: A body part specific simulated CAT developed from an LFS item bank was efficient and produced precise measures of LFS without eroding discriminant validity.

Activities of Daily Living↗
PubMed2006

Preoperative function and gender predict pattern of functional recovery after hip and knee arthroplasty.

Gender, preoperative function, and other variables were explored as predictors of recovery after total hip and knee arthroplasty. One hundred fifty-two subjects (63.8 +/- 10.2 years) were repeatedly assessed in the first 4 postoperative months. Average recovery curves for the Western Ontario and McMaster Universities Osteoarthritis Index, 6-minute walk test, and timed up and go test were characterized using hierarchical linear modeling. Recovery predictors were sequentially modeled after validation of the basic developmental models. Gender was a significant predictor (P < or= .003) of physical performance measure scores 1 week after surgery. Thereafter, men and women had similar rates of improvement. Preoperative score was a significant predictor (P < or= .001) in all models. Patients' and surgeons' expectations of outcome need to take preoperative function into account.

Aged↗
PubMed2006

Performance measures provide assessments of pain and function in people with advanced osteoarthritis of the hip or knee.

BACKGROUND AND PURPOSE: Pain and physical function are core outcome measures for people with osteoarthritis, and self-report questionnaires have been the preferred assessment method. There is evidence suggesting that self-reports of physical function represent what people experience when performing activities rather than their ability to perform activities. The purpose of this study was to examine the factorial validity of performance-specific assessments of pain and function. SUBJECTS: The sample consisted of 177 participants who had osteoarthritis of the hip (n=81) or knee (n=96) and who were awaiting total joint arthroplasty. METHODS: Through a cross-sectional design, participants performed 4 performance activities (self-paced walk test, stair test, Timed "Up & Go" Test, and Six-Minute Walk Test). OUTCOMES: were time or distance (function) and pain ratings obtained immediately after each activity. The authors conceptualized 2 correlated factors, with pain items loading uniquely on 1 factor and functional items loading on the second factor, and uncorrelated error terms. Confirmatory factor analysis was applied. RESULTS: Initial analysis yielded results consistent with the conceptualized model in this study with the exception of a nonzero correlation between the stair pain and function error terms. Dropping the stair test provided results consistent with the conceptualized model. DISCUSSION AND CONCLUSION: Given the limitations of self-report alone as a method of obtaining reasonably distinct assessments of pain and function, the extent to which performance-specific assessments could accomplish this goal was examined in this study. It was found that collectively the walk test, Timed "Up & Go" Test, and Six-Minute Walk Test yielded 2 factors consistent with the health concepts of pain and function. The authors believe that the application of these tests may provide clinicians and clinical researchers with more distinct impressions of pain and function that complement information from self-report measures.

Aged↗
PubMed2006

Comparing 2 versions of the Chedoke Arm and Hand Activity Inventory with the Action Research Arm Test.

BACKGROUND AND PURPOSE: The Chedoke Arm and Hand Activity Inventory (CAHAI) is a new, validated upper-limb measure that uses a 7-point quantitative scale in order to assess functional recovery of the arm and hand after a stroke. The purposes of this study were: (1) to determine whether the longitudinal validity of scores on 2 versions of a new upper-limb measure, the CAHAI (CAHAI-9 and CAHAI-13), was greater than that of scores on the Action Research Arm Test (ARAT) and (2) to determine whether the cross-sectional and longitudinal validity of the CAHAI-13 scores was greater than that of the CAHAI-9 scores. SUBJECTS: One hundred five people with upper-limb dysfunction following a stroke were stratified into 2 impairment groups (mild to moderate and severe), which were expected to change by different amounts. METHODS: The CAHAI-13 and ARAT were administered twice (time between assessments varied from 2 to 6 weeks). Receiver operating characteristic curves, Pearson product moment coefficient of correlation, and regression analyses were used. RESULTS: Receiver operating characteristic curve areas (CAHAI-13=0.86, CAHAI-9=0.82, ARAT=0.72) were significantly greater for the CAHAI versions. Scores on both CAHAI versions had identical levels of cross-sectional validity. DISCUSSION AND CONCLUSION: Both CAHAI versions demonstrated more sensitivity to change than the ARAT. It remains unclear whether the CAHAI-9 provides precise estimates of CAHAI-13 scores at the individual level.

Activities of Daily Living↗
PubMed2005

Performance measures were necessary to obtain a complete picture of osteoarthritic patients.

OBJECTIVES: Self-report questionnaires and performance measures represent two methods for assessing physical function. A recurring theme is that self-report measures are superior to performance measures. This study investigated the association between three performance test outcomes of four activities (pain, exertion, and time or distance; for self-paced walk, stair test, timed up-and-go, 6-minute walk) with self-reports of physical function (WOMAC Physical Function subscale and LEFS) and the association between the change scores of the performance tests and those of the self-report measures. STUDY DESIGN AND SETTING: Performance and self-report measures were administered three times (presurgery and at approximately 1 week and approximately 8 weeks post arthroplasty) to 85 patients who underwent total hip or knee arthroplasty. Components of the performance tests were pooled within each domain across the four measures. Multiple regression analyses were applied. Independent variables were performance tests components; dependent variables were self-report measures. Standardized regression coefficients described the cross-sectional and longitudinal associations. RESULTS: Pain was the principal determinant of WOMAC Physical Function subscale scores. Pain, exertion, and time or distance were strongly associated with the LEFS at the first, second, and third assessments, respectively. Change in pain was most strongly associated with change in self-reported physical function. CONCLUSION: Our findings caution against the isolated use of self-report assessments of physical function.

Aged↗
PubMed2005

Assessing sensitivity to change: choosing the appropriate change coefficient.

The past 20-years have seen the development and evaluation of many health status measures. Unlike the high standards demanded of those who conduct and report clinical intervention trials, the methodological rigor for studies examining the sensitivity to change of health status measures are less demanding. It is likely that the absence of a criterion standard for change in health status contributes to this shortcoming. To increase confidence in the results of these types of studies investigators have often calculated multiple change coefficients for the same patient sample. The purpose of this report is to identify the conflict that arises when multiple change coefficients are applied to the same patient sample. Three families of change coefficients based on different assumptions concerning the sample composition are identified: (1) the sample is homogeneous with respect to change; (2) subgroups of patients who truly change by different amounts exist; (3) individual patients, many of whom truly change by different amounts exist. We present several analyses which illustrate a major conceptual conflict: the signal (a measure's true ability to detect change) for some of these coefficients appears in the noise term (measurement error) of the others. We speculate that this dilemma occurs as a result of insufficient preparatory work such as pilot studies to establish the likely change characteristic of the patient population of interest. Uncertainty in the choice of change coefficient could be overcome by conducting pilot studies to ascertain the likely change characteristic of the population of interest. Once the population's change characteristic is identified, the choice of change coefficient should be clear.

Analysis of Variance↗
PubMed2005

Assessing stability and change of four performance measures: a longitudinal study evaluating outcome following total hip and knee arthroplasty.

BACKGROUND: Physical performance measures play an important role in the measurement of outcome in patients undergoing hip and knee arthroplasty. However, many of the commonly used measures lack information on their psychometric properties in this population. The purposes of this study were to examine the reliability and sensitivity to change of the six minute walk test (6MWT), timed up and go test (TUG), stair measure (ST), and a fast self-paced walk test (SPWT) in patients with hip or knee osteoarthritis (OA) who subsequently underwent total joint arthroplasty. METHODS: A sample of convenience of 150 eligible patients, part of an ongoing, larger observational study, was selected. This included 69 subjects who had a diagnosis of hip OA and 81 diagnosed with knee OA with an overall mean age of 63.7 +/- 10.7 years. Test-retest reliability, using Shrout and Fleiss Type 2,1 intraclass correlations (ICCs), was assessed preoperatively in a sub-sample of 21 patients at 3 time points during the waiting period prior to surgery. Error associated with the measures' scores and the minimal detectable change at the 90% confidence level was determined. A construct validation process was applied to evaluate the measures' abilities to detect deterioration and improvement at two different time points post-operatively. The standardized response mean (SRM) was used to quantify change for all measures for the two change intervals. Bootstrapping was used to estimate the 95% confidence intervals (CI) for the SRMs. RESULTS: The ICCs (95% CI) were as follows: 6MWT 0.94 (0.88,0.98), TUG 0.75 (0.51, 0.89), ST 0.90 (0.79, 0.96), and the SPWT 0.91 (0.81, 0.97). Standardized response means varied from .79 to 1.98, being greatest for the ST and 6MWT over the studied time intervals. CONCLUSIONS: The test-retest estimates of the 6MWT, ST, and the SPWT met the requisite standards for making decisions at the individual patient level. All measures were responsive to detecting deterioration and improvement in the early postoperative period.

Aged↗
PubMed2005

Test-retest reliability, validity, and sensitivity of the Chedoke arm and hand activity inventory: a new measure of upper-limb function for survivors of stroke.

OBJECTIVES: To estimate the test-retest reliability and validity of the Chedoke Arm and Hand Activity Inventory (CAHAI) and to test whether the CAHAI was more sensitive to change in upper-limb function than the Impairment Inventory of the Chedoke-McMaster Stroke Assessment (CMSA) and the Action Research Arm Test (ARAT). DESIGN: Construct validation process. SETTING: Inpatient/outpatient rehabilitation facilities. PARTICIPANTS: Stratified sample of 39 survivors of stroke: 24 early (mean age, 71.4 y; mean days poststroke, 27.3) and 15 chronic (mean age, 64.0 y; mean days poststroke, 101.7). INTERVENTION: Regular therapy. MAIN OUTCOME MEASURES: Intraclass correlation coefficients (ICCs), receiver operating characteristic (ROC), standard error of measurement, and correlation coefficients. RESULTS: High interrater reliability was established with an ICC of .98 (95% confidence interval [CI], .96-.99). The minimal detectable change score was 6.3 CAHAI points. Higher correlations were obtained between the CAHAI and the ARAT and CMSA scores compared with the CMSA shoulder pain scores (1-sided, P=.001). Areas under the ROC curves were as follows: CAHAI, .95 (95% CI, 0.87-1.00); CMSA, .76 (95% CI, .61-.92); and ARAT, .88 (95% CI, 0.76-1.00). CONCLUSIONS: High interrater reliability and convergent and discriminant cross-sectional validity were established for the CAHAI. The CAHAI is more sensitive to clinically important change than the ARAT.

Adult↗
PubMed2005

Simulated computerized adaptive tests for measuring functional status were efficient with good discriminant validity in patients with hip, knee, or foot/ankle impairments.

BACKGROUND AND OBJECTIVE: To develop computerized adaptive tests (CATs) designed to assess lower extremity functional status (FS) in people with lower extremity impairments using items from the Lower Extremity Functional Scale and compare discriminant validity of FS measures generated using all items analyzed with a rating scale Item Response Theory model (theta(IRT)) and measures generated using the simulated CATs (theta(CAT)). METHODS: Secondary analysis of retrospective intake rehabilitation data. RESULTS: Unidimensionality of items was strong, and local independence of items was adequate. Differential item functioning (DIF) affected item calibration related to body part, that is, hip, knee, or foot/ankle, but DIF did not affect item calibration for symptom acuity, gender, age, or surgical history. Therefore, patients were separated into three body part specific groups. The rating scale model fit all three data sets well. Three body part specific CATs were developed: each was 70% more efficient than using all LEFS items to estimate FS measures. theta(IRT) and theta(CAT) measures discriminated patients by symptom acuity, age, and surgical history in similar ways. theta(CAT) measures were as precise as theta(IRT) measures. CONCLUSION: Body part-specific simulated CATs were efficient and produced precise measures of FS with good discriminant validity.

Activities of Daily Living↗
PubMed2005

Intra- and inter-rater reliability of the anterior atlantodental interval measurement from conventional lateral view flexion/extension radiographs.

An investigation of intra- and inter-rater reliability anterior atlantodental interval (AADI) measurements was conducted using flexion/extension plain radiographs. Flexion and extension lateral radiographs of individuals investigated for atlantoaxial instability were measured for AADI on three occasions. Intra-rater intraclass correlation coefficients (ICC) were calculated for both flexion (0.99) and extension (0.96). Inter-rater ICCs were 0.93 and 0.84 for flexion and extension, respectively. The AADI measurement proved to be reproducible with a minimal standard of error, between and within raters.

Adolescent↗
PubMed2004

Does parallel item content on WOMAC's pain and function subscales limit its ability to detect change in functional status?

BACKGROUND: Although the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) is considered the leading outcome measure for patients with osteoarthritis of the lower extremity, recent work has challenged its factorial validity and the physical function subscale's ability to detect valid change when pain and function display different profiles of change. This study examined the etiology of the WOMAC's physical function subscale's limited ability to detect change in the presence of discordant changes for pain and function. We hypothesized that the duplication of some items on the WOMAC's pain and function subscales contributed to this shortcoming. METHODS: Two eight-item physical function scales were abstracted from the WOMAC's 17-item physical function subscale: one contained activities and themes that were duplicated on the pain subscale (SIMILAR-8); the other version avoided overlapping activities (DISSIMILAR-8). Factorial validity of the shortened measures was assessed on 310 patients awaiting hip or knee arthroplasty. The shortened measures' abilities to detect change were examined on a sample of 104 patients following primary hip or knee arthroplasty. The WOMAC and three performance measures that included activity specific pain assessments--40 m walk test, stair test, and timed-up-and-go test--were administered preoperatively, within 16 days of hip or knee arthroplasty, and at an interval of greater than 20 days following the first post-surgical assessment. Standardized response means were used to quantify change. RESULTS: The SIMILAR-8 did not demonstrate factorial validity; however, the factorial structure of the DISSIMILAR-8 was supported. The time to complete the performance measures more than doubled between the preoperative and first postoperative assessments supporting the theory that lower extremity functional status diminished over this interval. The DISSIMILAR-8 detected this deterioration in functional status; however, no significant change was noted for the SIMILAR-8. The WOMAC pain scale demonstrated a slight reduction in pain and the performance specific pain measures did not reflect a change in pain. All measures showed substantial improvement over the second assessment interval. CONCLUSIONS: These findings support the hypothesis that activity overlap on the pain and function subscales plays a causal role in limiting the WOMAC physical function subscale's ability to detect change.

Activities of Daily Living↗
PubMed2004

Condition-specific Western Ontario McMaster Osteoarthritis Index was not superior to region-specific Lower Extremity Functional Scale at detecting change.

OBJECTIVE: We determined whether the sensitivity to change of the Western Ontario McMaster Osteoarthritis Index (WOMAC) physical function (PF) subscale, a condition-specific measure for persons with osteoarthritis of the hip or knee, was superior to a lower extremity region-specific measure, the Lower Extremity Functional Scale (LEFS), in persons with osteoarthritis of the hip or knee undergoing total joint arthroplasty. METHODS: The WOMAC and LEFS were administered to 102 patients with osteoarthritis preoperatively, within 16 days of surgery, and >20 days after the first postoperative assessment. These time points enabled the assessment of deterioration and improvement. Two timed performance measures (40 m walk test and the timed-up-and-go test) were also assessed. Change was quantified by the standardized response mean (SRM). RESULTS: WOMAC PF SRMs were not greater than the LEFS SRMs. Performance measures' times increased significantly over the deterioration interval and decreased over the improvement interval. The WOMAC PF and LEFS demonstrated significant improvement over the second assessment interval; only the LEFS showed significant deterioration over the first assessment interval. WOMAC PF scores seem to be strongly influenced by pain. CONCLUSION: The findings do not support the hypothesis that the WOMAC PF subscale is superior to the LEFS in detecting change.

Aged↗
PubMed2004

The evaluation of change in pain intensity: a comparison of the P4 and single-item numeric pain rating scales.

STUDY DESIGN: Prospective observation study. OBJECTIVES: To compare the test-retest reliability and longitudinal validity (sensitivity to change) of 2 single-item numeric pain rating scales (NPRSs) with a 4-item pain intensity measure (P4). BACKGROUND: Pain is a frequent outcome measure for patients seen in physical therapy; however, the error associated with efficient pain measures, such as the single-item NPRS, is greater than for self-report measures of functional status. Initial evaluation of the P4 suggests that it is more reliable and sensitive to change than the NPRS. METHODS AND MEASURES: Two single-item NPRSs and the P4 were administered on 3 occasions--initial visit (n = 220), within 72 hours of baseline (n = 213), and 12 days following baseline assessment (n = 183)--to patients with musculoskeletal problems receiving physical therapy. Reliability was assessed using a type 2,1 intraclass correlation coefficient. Longitudinal validity was assessed by correlating the measures' change scores with a retrospective rating of change that included patients' and clinicians' perspectives. RESULTS: The test-retest reliability and longitudinal validity of the P4 were significantly greater (P1<.05) than both single-item NPRSs. Minimal detectable change of the P4 at the 90% confidence level was estimated to be a change of 22% of the scale range (9 points) compared to 27.3% (3 points) and 31.8% (3.5 points) for the 2-day NPRS and 24-hour NPRS, respectively. CONCLUSIONS: The findings of this study suggest the P4 is more adept at assessing change in pain intensity than popular versions of single-item NPRSs.

Adult↗
PubMed2003

The relationship between self-report and performance-related measures: questioning the content validity of timed tests.

OBJECTIVE: To examine the determinants of the modest correlation between self-report and performance-related measures in patients with osteoarthritis of the hip or knee. METHODS: Measures included the Lower Extremity Functional Scale (LEFS), the self paced walk, timed up-and-go, and stair test. Each performance measure consisted of 3 domains: time, pain (visual analog scale), and exertion (Borg scale). Activity specificity was assessed by examining correlations between the LEFS with single activity and multiple activity time scores. Domain specificity was examined by comparing correlations between the LEFS and single and multiple domain scores. The impact of measurement error was considered. RESULTS: Increasing the number of activity time scores had no effect. Forming a composite performance score based on time, pain, and exertion substantially increased the correlation from 0.44 (composite timed score) to 0.59 (pooled domain and activity score) (P = 0.009). CONCLUSION: Performance scores based on time alone appear to inadequately represent the breadth of health concepts associated with functional status.

Activities of Daily Living↗
PubMed2002

Comparison of gender and group differences in self-report and physical performance measures in total hip and knee arthroplasty candidates.

Functional measures (fast self-paced walk test, stair climb, and timed up and go) and a self-report measure of function (Lower Extremity Activity Profile) were assessed in 1,805 total hip (761) and knee (1044) arthroplasty candidates (1,063 women, 742 men) preoperatively. Women represented 59% of the study subjects and showed greater disability than men (P <or= .001) in the physical performance and self-report measures. Although the hip arthroplasty group perceived greater functional disability and less satisfaction, the impact of osteoarthritis on the hip and knee was similar in terms of walking and stair performance. Overall, there was low-to-moderate correlation between the self-report and physical performance measures (r = .21- .50).

Activities of Daily Living↗