Psychometric Evaluation of Joint-Specific Patient-Reported Outcome Measures Before and After Total Knee Replacement: A Dissertation

Background: Patient reports of pain and function are used to inform the need for and timing of total knee replacement (TKR) and evaluate TKR outcomes. This dissertation compared measurement properties of commonly-used patient surveys in TKR and explored ways to develop more efficient knee-specific function measures. Methods: 1,179 FORCE-TJR patients (mean age=66.1, 61% female) completed questionnaires before and 6 months after TKR. Patient surveys included the knee-specific Knee injury and Osteoarthritis Outcome Score (KOOS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and generic SF-36 Health Survey. Tests of KOOS and WOMAC measurement properties included evaluations of scaling assumptions and reliability. Item response theory methods were used to calibrate 22 KOOS function items in one item bank; simulated computerized adaptive tests (CAT) then were used to evaluate shorter function scores customized for each patient. Validity and responsiveness of measures varying in attributes (knee-specific versus generic, longer versus shorter, CAT versus fixed-length) were compared. Results: KOOS and WOMAC scales generally met tests of scaling assumptions, although many pain items were equally strong measures of pain and physical function. Internal consistency reliability of KOOS and WOMAC scales exceeded minimum levels of 0.70 recommended for group-level comparisons across sociodemographic and clinical subgroups. Function items could be calibrated in one item bank. CAT simulations indicated that reliable knee-specific function scores could be estimated for most patients with a 55-86% reduction in respondent burden, but one-third could not achieve a reliable (≥ 0.95) CAT score post-TKR because the item bank did not include enough items vi measuring high function levels. KOOS and WOMAC scales were valid and responsive. Short function scales and CATs were as valid and responsive as longer KOOS and WOMAC function scales. The KOOS Quality of Life (QOL) scale and SF-36 Physical Component Summary discriminated best among groups evaluating themselves as improved, same or worse at 6 months. Conclusions: Results support use of the KOOS and WOMAC in TKR. Improved knee-specific function measures require new items that measure higher function levels. TKR outcomes should be evaluated with a knee-specific quality of life scale such as KOOS QOL, as well as knee-specific measures of pain and function and generic health measures

Cross-cultural adaptation of the SF-36 and SF-12 Physical and Mental Summary Scales on a Chinese Population

Abstractpreprin

Is the standard SF-12 Health Survey valid and equivalent for a Chinese population?

Introduction: Chinese is the world's largest ethnic group but few health-related quality of life (HRQoL) measures have been tested on them. The aim of this study was to determine if the standard SF-12 was valid and equivalent for a Chinese population. Methods: The SF-36 data of 2410 Chinese adults randomly selected from the general population of Hong Kong (HK) were analysed. The Chinese (HK) specific SF-12 items and scoring algorithm were derived from the HK Chinese population data by multiple regressions. The SF-36 PCS and MCS scores were used as criteria to assess the content and criterion validity of the SF-12. The standard and Chinese (HK) specific SF-12 PCS and MCS scores were compared for equivalence. Results: The standard SF-12 explained 82% and 89% of the variance of the SF-36 PCS and MCS scores, respectively, and the effect size differences between the standard SF-36 and SF-12 scores were less than 0.3. Six of the Chinese (HK) specific SF-12 items were different from those of the standard SF-12, but the effect size differences between the Chinese (HK) specific and standard SF-12 scores were mostly less than 0.3. Conclusions: The standard SF-12 was valid and equivalent for the Chinese, which would enable more Chinese to be included in clinical trials that measure HRQoL. © Springer 2005.postprin

Population based norming of the Chinese (HK) version of the SF-36 health survey

Objective: The aim of this study was to establish normative values of the SF-36 Health Survey of the Chinese adult population in Hong Kong so that local references for meaningful interpretation of health-related quality of life (HRQOL) measurements would be available. Design: A cross-sectional telephone survey. Subject: Chinese adults aged 18 years or above randomly selected from the general population in Hong Kong. Main outcome measures: The Chinese (HK) SF-36 Health survey and demographic variables. The normative values of the SF-36 of the general population and different age/sex groups. Results: 2410 subjects completed the survey. The SF-36 scores on Physical Functioning, Role-physical, Bodily Pain and Social Functioning of the study sample were higher but the scores on General Health, Role-emotional and Mental Health were lower than those of the US norms. Age and gender had significant and substantial effects on the SF-36 scores. There was a social class gradient on the General Health, Vitality and Mental Health scores. Other demographic factors had little or no effects on the SF-36 scores. Conclusion: The Chinese (HK) version of the SF-36 is, at present, the only HRQOL measure that has been both validated and normed on Chinese adults in Hong Kong. It can be used as a standard HRQOL instrument to measure the impact of illnesses and the effect of interventions on the quality of life of our Chinese population.published_or_final_versio

Psychometrics and population norm of the Chinese (HK) SF-36 Health Survey_version 2

Objective: To establish the psychometric properties and norm of the Chinese (HK) SF-36 version 2 Health Survey for the adult population in Hong Kong (HK) to facilitate its application and interpretation. Design: A cross-sectional random telephone survey of the general adult population. Subjects: 2410 Chinese adults randomly selected from the general Chinese adult population in Hong Kong. The mean age of the subjects was 42.9 (S.D. 17.3) years, 48% were men and 38% had one or more chronic disease. Main outcome measures: Responses to the SF-36v2 Health Survey questions were extracted. Item-scale correlations, internal and test-retest reliabilities, and the factor structure of the SF-36v2 Health Survey scores were analysed. The SF-36v2 Health Survey scores were calculated by the standard algorithm to establish the population norm. Results: All items had 100% scaling success indicating discriminant validity. Internal consistency and test-retest reliabilities of all scales were good (coefficients 0.66 to 0.89). The hypothesized two-factor structure underlying construction of the physical and mental health summary scales was confirmed. The psychometric properties of the SF-36v2 Health Survey were generally better than version 1. There were significant differences in the population norms between versions 1 and 2 of the Chinese (HK) SF-36 Health Survey, especially in the role-physical and role-emotional scales. Conclusion: The Chinese (HK) SF-36v2 Health Survey is valid and reliable for measuring HRQOL of Chinese adults in Hong Kong, and population norm is now available to support the interpretation of its scores.published_or_final_versio

Tests of scaling assumptions and construct validity of the Chinese (HK) version of the SF-36 Health Survey

Few health-related quality of life (HRQOL) survey instruments are available to the Chinese, although many have been developed for Western populations. This article describes the testing of the acceptability, conceptual equivalence, scaling assumptions and construct validity of a Chinese (HK [Hong Kong]) version of the MOS SF-36 Health Survey. A Chinese (HK) SF-36 survey form was developed by an iterative translation process. It was administered to 236 Chinese subjects who also rated the understanding, difficulty, relevance, and acceptability of each question. The scores were tested against the original scaling assumptions. The SF-36 profile of our subjects was compared to U.S. results for conceptual equivalence. Most subjects did not have any problem in understanding and answering the SF-36. Item means were generally clustered as hypothesized. All but a few items satisfied all scaling assumptions. The shape of the eight-scale SF-36 profile was similar to that of American patients, suggesting conceptual equivalence. We conclude that the Chinese (HK) version of the SF-36 Health Survey has achieved conceptual equivalence and satisfied the psychometric scaling assumptions well enough to warrant further use and testing, using the standard scoring algorithms.postprin

The SF-36 summary scales were valid, reliable, and equivalent in a Chinese population

Objectives: To find out whether the SF-36 physical and mental health summary (PCS and MCS) scales are valid and equivalent in the Chinese population in Hong Kong (HK). Study Design and Setting: The SF-36 data of a cross-sectional study on 2,410 Chinese adults randomly selected from the general population in HK were analyzed. Results: The hypothesized two-factor structure of the physical and mental health summary scales (PCS and MCS) was replicated and the expected differences in scores between known morbidity groups were shown. The internal reliability coefficients of the PCS and MCS scales ranged from 0.85 to 0.87. The effect size differences between the U.S. standard and HK-specific PCS and MCS scores were mostly <0.5. The effect size differences in the standard PCS and MCS scores of specific groups between the U.S. and H.K. populations were all <0.5. Conclusion: The PCS and MCS scales were applicable to the Chinese population in HK. The high level of measurement equivalence of the scales between the U.S. and H.K. populations suggests that data pooling between the two populations could be possible. To our knowledge, this is the first study to show that the SF-36 summary scales are valid and equivalent in an Asian population. © 2005 Elsevier Inc. All rights reserved.postprin

A Comparison of Cellular Uptake Mechanisms, Delivery Efficacy, and Intracellular Fate between Liposomes and Extracellular Vesicles

A key aspect for successful drug delivery via lipid-based nanoparticles is their internalization in target cells. Two prominent examples of such drug delivery systems are artificial phospholipid-based carriers, such as liposomes, and their biological counterparts, the extracellular vesicles (EVs). Despite a wealth of literature, it remains unclear which mechanisms precisely orchestrate nanoparticle-mediated cargo delivery to recipient cells and the subsequent intracellular fate of therapeutic cargo. In this review, internalization mechanisms involved in the uptake of liposomes and EVs by recipient cells are evaluated, also exploring their intracellular fate after intracellular trafficking. Opportunities are highlighted to tweak these internalization mechanisms and intracellular fates to enhance the therapeutic efficacy of these drug delivery systems. Overall, literature to date shows that both liposomes and EVs are predominantly internalized through classical endocytosis mechanisms, sharing a common fate: accumulation inside lysosomes. Studies tackling the differences between liposomes and EVs, with respect to cellular uptake, intracellular delivery and therapy efficacy, remain scarce, despite its importance for the selection of an appropriate drug delivery system. In addition, further exploration of functionalization strategies of both liposomes and EVs represents an important avenue to pursue in order to control internalization and fate, thereby improving therapeutic efficacy

Cultural Issues in Using the SF-36 Health Survey in Asia: Results from Taiwan

BACKGROUND: The feasibility of using the SF-36 in non-Western cultures is important for researchers seeking to understand cultural influences upon health status perceptions. This paper reports on the performance of the Taiwan version of the SF-36, including the implications of cultural influences. METHODS: A total of 1191 volunteered subjects from the general population answered the translated SF-36 Taiwan version, which was developed following IQOLA project protocols. RESULTS: Results from tests of scaling assumptions and reliability generally were satisfactory. Convergent validity, as assessed by comparing the SF-36 to a mental health oriented inventory, was acceptable. Results of principal components analysis were similar to US results for many scales. However, differences were seen for the Vitality scale which was a stronger measure of mental health than physical health in Taiwan. Results are compared to those from other Asian studies and the U.S. CONCLUSION: The results raise important questions regarding cultural influences in international studies of health status assessment. Further research into the conceptualization and components of mental health in Asian countries is warranted