Original Article
Tests of Scaling Assumptions and Construct Validity of the Chinese (HK) Version of the SF-36 Health Survey

https://doi.org/10.1016/S0895-4356(98)00105-XGet rights and content

Abstract

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 fo 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.

Introduction

Rapid economic development in Hong Kong has resulted in an increase in life expectancy and aging of the population. The average life expectancy is 81 years for women and 76 years for men in Hong Kong [1]. The proportion of the population who are 65 years or older has doubled from the 4.5% in 1971 to 9% in 1996. Chronic disabling diseases such as stroke and arthritis have become the major health problems, although they are often not lethal, they can affect the quality of life and place a substantial burden on the health care system. Traditional indicators such as mortality and objective clinical parameters are no longer sufficient to assess the effect of illness and the outcome of treatments. They have to be supplemented with self-rated health-related quality of life (HRQOL) measures 2, 3, 4. The HRQOL measure has been found to be valid and sensitive in predicting mortality in the elderly [5], detecting functional impairment [6], and determining consultation rates [7]. There is an increasing demand for a valid and acceptable HRQOL measure for the people in Hong Kong.

Although many HRQOL measures have been developed in the last two decades in Western countries [8], few are applicable to the people in Hong Kong. The major obstacle is the cultural and language difference between the populations of Hong Kong and Western countries. Ninety-six percent of the population of Hong Kong is Chinese, their written language is Chinese, and the daily spoken language is Cantonese. Only 30% of the population can speak English [1]. Translation into Chinese and testing for cross-cultural validity are required before a HRQOL survey form can be applied to the people in Hong Kong.

The MOS 36-Item Short Form Health Survey (SF-36) developed by Ware et al. in the United States is gaining international popularity 9, 10. It consists of 36 items grouped under 11 questions. The scores of the 36 items are summated into eight multiitem scales: physical functioning (PF), limitations due to physical health problems (role-physical; RP), bodily pain (BP), general health (GH), vitality (VT), social functioning (SF), limitations due to emotional health problems (role-emotional; RE), and mental health (MH) and one single-item scale on health transition. Higher scores represent better health status. The SF-36 captures most of the important concepts of HRQOL 4, 11 and has been shown to be useful in general and clinical populations [9].

At the time of this writing, the SF-36 has been translated and tested in more than 40 countries and normed in 12 countries. Ren et al. [12] developed and tested a Chinese version of the SF-36 on Chinese Americans, but its acceptability or validity on Chinese people living in Asia is not known.

The aim of our study was to test the acceptability, conceptual equivalence, scaling assumptions and construct validity of a Chinese (HK) version of the SF-36. If these tests are met and other tests of validity confirmed, the Chinese (HK) SF-36 would have potential application to Chinese people living in Hong Kong as well as on those who have migrated from Hong Kong to other countries. We hope that our work will stimulate a wider use of HRQOL as a health and outcome indicator in the care of nearly one quarter of the world’s population who is Chinese.

Section snippets

Method

The International Quality of Life Assessment (IQOLA) project has developed a three-stage method for cross-cultural adaptation of the MOS SF-36 Health Survey [10]. The first is translation of the original survey into the native language and evaluation to ensure conceptual equivalence and respondent acceptance, to produce a form that can be used in data collection. The second stage is formal psychometric tests of the assumptions underlying item scoring and construction of multitem scales, to

Sample

Two hundred thirty-six Chinese subjects (185 clinic patients, and 51 university students) were surveyed. There were 184 (78%) females and 52 (22%) males. The mean age of the subjects was 43 years (standard deviation [SD], 18.3; range, 15–93). The social class distribution was 3 (1.3%) professionals (I), 12 (5.1%) associate professionals (II), 115 (48.7%) skilled workers (III), 46 (19.5%) semiskilled workers (IV), and 60 (25,4%) unskilled workers (V). Fifty-two subjects (22%) had no formal

Discussion

We used two sampling frames in our study in order to include subjects from both genders, a wide range of ages, different social classes, and all educational levels in the testing of the Chinese (HK) SF-36. A much larger sample size would be needed if subjects were randomly selected from the general population, in order to include people from extreme age and social groups. We believe that our results on the acceptability, conceptual equivalence, construct validity, and psychometric properties of

Conclusions

The Chinese (HK) version of the SF-36 was found to be equivalent in concepts to the original U.S.-English SF-36. It was well understood and accepted by Chinese people with different demographic characteristics in Hong Kong. Our results confirmed the scaling assumptions and construct validity of the Chinese (HK) SF-36. Therefore, the Chinese (HK) SF-36 scale can be scored using the standard scoring algorithms [9].

The Chinese (HK) SF-36 has completed the first two stages of the IQOLA Project

Acknowledgements

This study was funded by the Committee of Research and Conference Grant, the University of Hong Kong. We are grateful to Dr. William Lin, Miss Ee San Chen, and Mr. Shaoming Lian for reviewing the translation. We thank our research assistants, Cyrina Chan and Ada Au, for their help in data collection and entry. Thanks also go to the staff of the IQOLA Project, the Health Institute, New England Medical Center, Boston, Massachusetts, for their assistance in data analysis.

References (23)

  • X.S. Ren et al.

    Translation and psychometric evaluation of a Chinese version of the SF-36 Health Survey in the United States

    J Clin Epidemiol

    (1998)
  • Census and Statistics Department. Hong Kong 1991 Population Census—Main Report. Hong Kong: Government Printer,...
  • K.N. Lohr

    Outcome measurementConcepts and questions

    Inquiry

    (1988)
  • S. Greenfield et al.

    Recent developments and future issues in the use of health status assessment measures in clinical settings

    Med Care

    (1992)
  • I.B. Wilson et al.

    Linking clinical variables with health-related quality of life

    JAMA

    (1995)
  • E.L. Idler et al.

    Self-evaluated health and mortality among the elderly in New Haven, Connecticut, and Iowa and Washington counties, Iowa, 1982–1986

    Am J Epidemiol

    (1990)
  • C.L.K. Lam

    Health outcome of stroke patients in Hong Kong

    Huisarts Wetenschap

    (1995)
  • C.L.K. Lam et al.

    A study of patients’ subjective perception of their health status

    HK Pract

    (1988)
  • A. Bowling

    Measuring health—A Review of Quality of Life Measurement Scales

    (1991)
  • J.E. Ware et al.

    SF-36 Health Survey—Manual and Interpretation Guide

    (1993)
  • J.E. Ware et al.

    Evaluating translations of health status questionnairesMethods from the IQOLA Project

    Int J Technol Assess Health Care

    (1995)
  • Cited by (393)

    View all citing articles on Scopus
    View full text