Cross-Cultural Use of Measurements:Development of the Chinese SF-36 Health Survey

Xinhua S. Ren, Ph.D.

• Boston University School of Public Health, Boston, MA

• Center for Health Quality, Outcomes, and Economic Research, Bedford Veterans Hospital, Bedford, MA

Funded by the Agency for Health Care and Policy Research

Outline

• Background• Need for non-English survey instruments• Strategies • Development of the Chinese SF-36 Health Survey • Psychometric testing• Application among elderly Chinese Americans

Introduction

• Health-related quality of life (HRQoL) measures are rapidly becoming standard tools

– assess health status– monitor patient health status – evaluate the quality, efficiency, and effectiveness of

patient care

Introduction (cont.)

• HRQoL measures are reliable and valid

• Easy to collect and for less cost

Demographic Transition and Cross-Cultural Use of Health Status Measures

• Ethnic diversity is transforming America into a multicultural society– By 2000, 25% minority populations– By 2050, > 50% minority populations

• An increased interest in providing culturally appropriate health care services

Demographic Transition and Cross-Cultural Use of Health Status Measures (cont.)

• Most HRQoL instruments have been developed in English

• The absence of information makes it difficult to plan and implement culturally responsive health care programs

Developing a Culturally-AppropriateHealth Status Measure

• To construct a new HRQoL measure– advantage: cultural specific

• To translate and adapt HRQoL measures previously developed and validated in English– advantage: appropriate for cross-cultural comparison

Two different strategies:

Translation and Adaptation ofHRQoL Measures

• Selection of health related quality of life measures

• Use of systematic approaches

Selection of Health Status Measures

• Reliability– produces consistent results

• Validity – measures what it is supposed to measure

• Easy administration– the amount of time required to complete the

instrument)

Three criteria:

Why SF-36?

Three considerations:

• SF-36 contains fewer questions to be administered

• SF-36 has been proven to be psychometrically sound

• SF-36 is based on a multidimensional model of health

MOS SF-36

– physical functioning (PF)– role limitations due to physical health (RP)– bodily pain (BP)– general health perceptions (GH)

• SF-36 measures 8 different domains of health

MOS SF-36 (cont.)

• SF-36 measures 8 different domains of health (cont.)

– vitality (VT)– social functioning (SF)– role limitations due to emotional problems (RE)– mental health (MH)

MOS SF-36 (cont.)

• The 8 scales are scored from 0 (worst health) to 100 (best health)

• The 8 scales can be combined into 2 summary scales– physical (PCS) & mental (MCS)– scored using a linear t score transformation, normed to

a general US population with a mean of 50 and a standard deviation of 10

Approach of Translation and Adaptation

• Two general principles– replicate the original as closely as possible– be sensitive to cultural adaptations

• Systematic protocols– Three forward translations– Committee review– Two back-ward translations– Committee review

Adaptation of MOS SF-36

• Adaptations on items that make little sense in Chinese– “full of pep” “liveliness” or “vigor”– “down in the dumps” “low in mood”– “downhearted and blue” “sadness”– “a mile” “a kilometer”– “several blocks” “several hundred meters”– “playing golf” “practicing Tai Chi”

Testing the Reliability and Validity of the Translation • Item-internal consistency

– the correlation between an item and its hypothesized scale > 0.40

• Internal consistency reliability (Cronbach’s alpha)– real variation as opposed to random error

• Test-retest reliability– consistent scores on two or more administrations

• Equivalent-Forms Reliability– agreement between the scores– consistent ordering of item mean scores

Testing the Reliability and Validity of the Translation (cont.)

• Construct validity (known-groups validity)– discriminating among various groups

Data

– A convenience sample of 156 respondents in Boston, Massachusetts (Sample 1)

– A convenience sample of 321 subjects from Tucson, Arizona (Sample 2)

– A convenience sample of 219 elderly Chinese in Boston, Massachusetts (Sample 3)

• Three data sources

Item-Internal Consistency (Sample 1) Vitality PF RP BP GH VT SF RE MH

VT1 .27 .44 .33 .38 .55* .40. .37 .41 VT2 .31 .52 .41 .50 .64* .46 .46 .51 VT3 .26 .35 .28 .41 .51* .48 .46 .58+ VT4 .20 .34 .22 .41+ .39* .34 .47+ .52+

SocialFunction

SF1 .22 .35 .40+ .34 .37 .39* .43+ .39+ SF2 .35 .46 .37 .48+ .54+ .39* .33 .50+

Internal Consistency Reliability(Cronbach’s alpha) (Sample 1)

SF-36 scales Cronbach’s alphaPF .92RP .82BP .78GH .82VT .73SF .54RE .88MH .74

One-Week Test-Retest Reliability (Sample 2)

Product-moment correlations

SF-36 Chinese-Chinese English-English (n = 77) (n = 78)

PF 0.90 0.81RP 0.69 0.70BP 0.68 0.83GH 0.74 0.78VT 0.83 0.79SF 0.67 0.80RE 0.78 0.84MH 0.86 0.87

Equivalent-forms Reliability (Sample 2)

SF-36 English-Chinese Chinese-English z-score(n = 75) (n = 79)

PF 0.98 0.82 6.93RP 0.81 0.92 -2.80BP 0.92 0.95 -1.47GH 0.88 0.88 0.00VT 0.97 0.88 4.35SF 0.90 0.87 0.84RE 0.94 0.99 -5.52MH 0.95 0.92 1.47

Construct Validity: Quality of the Translation Item means

SF-36 PF Chinese U.S.

Vigorous activities 1.87 2.17

Climb several flights 2.50 2.54

Bend, kneel 2.59 2.59

Walk mile 2.57 2.55

Moderate Activities 2.44 2.65

Lift, carry groceries 2.67 2.72

Walk several blocks 2.67 2.69

Climb one flight 2.83 2.78

Walk one block 2.86 2.82

Bathe, dress 2.89 2.88

Construct Validity: SF-36 health profile for various Chinese groups and U.S. norm

0

25

50

75

100

PF RP BP GH VT SF RE MHGeneral patients Dialysis patientsStudents Community subjectsElderly U.S. Norm

Applying the Chinese SF-36 among Elderly Chinese

• Limited Health Status Data

– The myth of a healthy minority model– Inappropriateness of using mortality to

assess health status– A high risk and high need population

Characteristics (N=219)Percent / Mean

• Age (range: 55-96) 69 (s.d.=7.6)• Female 61%• Married 68% • < Middle school 59%• Income

< $9,999 59%$10,000-29,999 31%$30,000 10%

• Length of stay, y 13 (s.d.=10.7)• Number of medical symptoms 1.6 (s.d.=1.4)

SF-36 Health Profiles for Elderly Chineseand U.S. Norm

SF-36 Chinese elderly U.S. norm U.S. normscales (mean age = 69) (ages 65-74) (ages 75)

(n = 219) (n = 442) (n = 264)

PCS 43.3 (9.0) 43.5 (11.2) 38.0 (11.2)*MCS 47.1 (10.9) 52.6 (9.3)* 50.8 (11.7)*

* P < 0.001 level.

Conclusions

– selection of currently available instrument over the development of new instruments

– need to conduct psychometric tests

• To develop valid and reliable cross-cultural measures

Conclusions (cont.):

• The translation and adaptation of the SF-36 into Chinese is successful– it satisfies conventional psychometric criteria– It discriminates well healthy populations from sick patients– It is valuable in general population surveys as well as

clinical practice or research– assisting doctors understand better about the feelings of

their Chinese patients– improving quality of patient care