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Biomedical subjects

M L Boey

Publications and source records attributed to M L Boey.

At least 19 recordsLinked to original sources
PubMed2004

Modelling variability of quality of life scores: a study of questionnaire version and bilingualism.

BACKGROUND AND OBJECTIVES: Modelling variability of quality of life scores can not only improve our understanding of the characteristics of the measurement tools, but also shed light on sample size requirements. Although the English and Chinese versions of the Short Form 36 Health Survey (SF-36) are commonly considered equivalent, they have not been compared in terms of variability. Furthermore, bilingual and monolingual persons may differ in cognition and responses to questionnaires. METHODS: In a community-based survey of quality of life in Singapore, a society where both English and Chinese are widely used and bilingualism is prevalent, 2590 respondents answered either version of the SF-36. We studied the impact of questionnaire version and bilingualism on the variability of SF-36 scores by regression modelling, with adjustment for covariates. RESULTS: The Chinese version had smaller variances in the physical functioning (PF) and the physical component summary scores than the English version. The variance ratios (VRs) were respectively 0.32 and 0.60 (each p < 0.01), controlling for covariates. Bilingualism was not associated with variability in SF-36 scores except PF (VR = 0.78; p < 0.05). CONCLUSIONS: As a result of a smaller variance, using the Chinese version of SF-36 among bilingual Chinese people may require a smaller sample size than using the English version.

Adult↗
PubMed2002

A Chinese version of the Rheumatology Attitudes Index is a valid and reliable measure of learned helplessness in patients with SLE.

Despite the prognostic importance of learned helplessness (LH) in rheumatic diseases, there are no validated measures of LH in Chinese or other Asian languages. We therefore assessed the validity of a Chinese translation of the Rheumatology Attitudes Index (CRAI; a widely used measure of LH) and its Helplessness (CHS) and Internality (CIS) subscales in patients with SLE. Chinese-speaking SLE patients (n = 69) completed identical, self-administered questionnaires containing the CRAI and assessing demographic/socio-economic variables twice within 2 weeks. SLE activity, damage and quality of life were assessed using the BILAG, SLICC/ACR Damage Index and SF-36 respectively. Scale psychometric properties were assessed through Cronbach's alpha, intra-class correlations, quantifying test-retest differences, factor analysis and known-groups construct validity. Internal consistency and reliability were acceptable, with Cronbach's alpha for the CHS, CIS and CRAI being 0.70, 0.69 and 0.74, respectively. Mean differences in test-retest scores spanned 1.6-2.4% of possible scale ranges and intra class correlations ranged from 0.72 to 0.88. Factor analysis identified two major factors corresponding to the CHS and CIS subscales of the CRAI. Eight of 10 a priori hypotheses relating the CRAI and CHS to demographic, disease and quality of life variables were confirmed, supporting the construct validity of these scales. The CRAI and its helplessness subscale are valid and reliable measures of learned helplessness in Chinese-speaking SLE patients.

Adolescent↗
PubMed2002

Measuring health-related quality of life in Singapore: normal values for the English and Chinese SF-36 Health Survey.

OBJECTIVE: To determine norms for assessing Health-related Quality of Life (HRQOL) in Singapore using the Short Form 36 Health Survey (SF-36). MATERIALS AND METHODS: Mean SF-36 scores were calculated for 24 population subgroups (categorised by age, gender, ethnicity and questionnaire language) and for subjects with self-reported co-morbid conditions using data from a community-based survey in Singapore. RESULTS: The English and Chinese SF-36 was completed by 4122 and 1381 subjects, respectively, 58% (n = 3188) of whom had self-reported co-morbid conditions. SF-36 scores varied in subgroups differing in age, gender and ethnicity. In general, subjects with self-reported co-morbid conditions had lower SF-36 scores than those without these conditions, the magnitude of which exceeded 20 points in several instances. A method for calculation of SF-36 scores adjusted for age, gender, ethnicity and questionnaire language is described. CONCLUSION: We present norms for English and Chinese SF-36 versions in Singapore and describe potential uses for these data in assessing HRQOL in Singapore.

Adult↗
PubMed2001

A comparative study of the clinical manifestations of systemic lupus erythematosus in Caucasians in Rochester, Minnesota, and Chinese in Singapore, from 1980 to 1992.

OBJECTIVE: To examine the relationship between ethnicity and major organ involvement at and after diagnosis in community-based cohorts of Caucasian and Chinese systemic lupus erythematosus (SLE) patients resident in Rochester, Minnesota, and Singapore, respectively. METHODS: Clinical manifestations at and after diagnosis were compared in Caucasian and Chinese SLE patients. The association between ethnicity and disease manifestations at and after diagnosis was determined using logistic regression and Cox proportional hazards models, respectively, adjusting for the influence of demographic, socioeconomic, disease-related, and therapy-related factors. RESULTS: At diagnosis, Caucasian SLE patients were 3 times more likely than Chinese SLE patients to have serositis (odds ratio [OR] 3.11, 95% confidence interval [CI] 1.01-9.71), nearly 7 times more likely to have a hematologic disorder (OR 6.95, 95% CI 2.20-21.97), and far less likely to have a malar rash (OR 0.19, 95% CI 0.07-0.54) or positive antinuclear antibodies (OR 0.11, 95% CI 0.03-0.52). Ethnicity was not associated with the prevalence of proteinuria or central nervous system (CSN) and other major organ involvement at diagnosis. After diagnosis, there was a trend toward less development of proteinuria and other major organ involvement in Caucasians (relative risk [RR] 0.47, 95% CI 0.19-1.15, and RR 0.22, 95% CI 0.05-1.04, respectively). CONCLUSION: Chinese SLE patients are far less likely to have serositis or a hematologic disorder at diagnosis and may be more likely to develop proteinuria or CNS or other major organ involvement over the course of the disease, compared with Caucasian SLE patients. This may contribute to the increased mortality seen in Chinese SLE patients.

Adolescent↗
PubMed2000

Validation of a Chinese version of the Medical Outcomes Study Family and Marital Functioning Measures in patients with SLE.

The objective was to validate a Chinese translation of the Medical Outcomes Study Family and Marital Functioning Measures (FFM and MFM) in patients with systemic lupus erythematosus (SLE). Chinese-speaking SLE patients (n = 69) completed a self-administered questionnaire containing the FFM and MFM and assessing demographic and socio-economic status twice within a 2 week period. SLE activity, disease-related damage and quality of life were assessed using the BILAG, SLICC/ACR Damage Index and SF-36 Health Survey, respectively. Scale psychometric properties were assessed through factor analysis, Cronbach's alpha, quantifying test-retest differences and known-groups construct validity. Factor analysis identified 1 factor corresponding to the FFM and 2 factors corresponding to the MFM. Internal consistency for the FFM was excellent (alpha = 0.92) while that for the MFM was acceptable (alpha = 0.62). Mean (s.d.) test-retest differences were 0.06 (1.54) points for the FFM and 0.03 (2.08) points for the MFM. 11 and 10 of 13 a priori hypotheses relating the FFM and MFM, respectively, to demographic, disease and quality of life variables were confirmed, supporting the construct validity of these scales. The Chinese FFM and MFM are valid and reliable measures of family and marital functioning in Chinese-speaking SLE patients, with psychometric properties very similar to the source English version.

Adolescent↗
PubMed2000

Validation of the Chinese SF-36 for quality of life assessment in patients with systemic lupus erythematosus.

We studied the reliability and validity of the Chinese Short-Form 36 Health Survey (SF-36) in a cross sectional study of patients with systemic lupus erythematosus (SLE). Sixty-nine consecutive subjects completed a questionnaire containing the Chinese SF-36 twice within 14 d. Disease activity and damage were assessed using the British Isles Lupus Activity Group (BILAG) and SLICC/ACR Damage Index (DI) scales, respectively. Internal consistency was assessed using Cronbach's alpha, reliability using Spearman's correlation and repeatability coefficients, and relationships between SF-36, BILAG and DI scores using Spearman's correlation. The Chinese SF-36 showed high internal consistency (alpha = 0.72-0.91) and good reliability, with correlations exceeding 0.70 for 7 scales and mean scale score differences of < 2 points for 6 scales. SF-36 scores correlated weakly with BILAG scores (-0.27 to -0.41) and DI scores (-0.24 to -0.35), and subjects' mean SF-36 scores were 6-24 points lower than the general population, supporting construct validity of the SP-36. These data suggest that the Chinese SF-36 is a reliable and valid measure of quality of life in patients with SLE.

Adolescent↗
PubMed2000

Primary and secondary pulmonary hypertension in systemic lupus erythematosus.

OBJECTIVES: To describe the aetiology and clinical profile of primary and secondary pulmonary hypertension (PHT) in SLE patients. METHODS: A retrospective study of SLE patients with PHT identified from a cohort of 786 SLE patients seen at Tan Tock Seng Hospital, Singapore. RESULTS: 22 patients had primary and 24 patients had secondary PHT, with similar clinical features at presentation and a similar degree of pulmonary pressure elevation. Secondary PHT was due to valvular heart disease (50%), pulmonary embolism (13%), interstitial lung disease (8%) or a combination of these factors (29%). Primary PHT tended to present after a shorter duration of lupus than secondary PHT (8.8 vs 43.2 months, P=0.118). At presentation, Raynaud's phenomenon was present in 34.8% of subjects with primary or secondary PHT. Among those with secondary PHT, the presence of Raynaud's phenomenon was associated with a trend towards higher pulmonary artery systolic pressures (51.0 vs 40.5 mmHg, P=0. 101). 17% of patients with PHT died, but from causes unrelated to PHT. CONCLUSION: Primary and secondary PHT are equally common in SLE patients. Secondary PHT is often multi-factorial, and Raynaud's phenomenon may be a marker for the severity of PHT in this group of patients.

Adult↗
PubMed2000

Accuracy of medical record scoring of the SLICC/ACR damage index for systemic lupus erythematosus.

OBJECTIVE: To study the accuracy of medical record scoring of the SLICC/ACR Damage Index (DI) for SLE. METHODS: Medical record DI (MDI) scoring of 60 SLE patients by one physician was compared with prospective direct DI (DDI) scoring a median of 2 y earlier. Agreement between DDI and MDI total and organ system scores was compared using Cohen's kappa, the degree of misclassification by MDI and the significance of differences between DDI and MDI scores. RESULTS: The mean duration of SLE at DDI scoring was 5.2 y. The median/mean (SD) DDI and MDI total scores were 0/0.78 (1.38) and 0/0. 85 (1.44). Damage was present on DDI and MDI scoring in 36.7% (22/60) and 38.3% (23/60) of patients. Qualitative MDI and DDI total scores (damage present/absent) showed good agreement (kappa=0.61, 95% CI=0.40-0.82, 18.3% misclassification). Quantitative MDI and DDI total scores (degree of damage) showed moderate agreement (kappa=0. 47, 95% CI=0.28-0.66, 36.7% misclassification). 9 of 12 MDI organ system scores misclassified <10% of subjects. There was no statistically significant difference between DDI and MDI total or organ system scores. CONCLUSION: MDI total scoring is a good qualitative and moderate quantitative reflection of SLE related damage. MDI organ system scores are more accurate than MDI total scores.

Adolescent↗
PubMed2000

A prospective study of factors affecting quality of life in systemic lupus erythematosus.

OBJECTIVE: To prospectively identify factors influencing quality of life (QOL) over 6 months in patients with systemic lupus erythematosus (SLE). METHODS: Ninety ethnically diverse patients with SLE completed questionnaires administered 6 months apart assessing QOL (using the Medical Outcomes Study Short Form-36) and demographic, socioeconomic, psychosocial, and behavioral factors. Disease activity, damage, and treatment were recorded at both evaluations. Multiple linear regression (adjusting for baseline health status) was used to identify factors influencing mental and physical health. RESULTS: Improved physical health after 6 months was associated with reductions in learned helplessness (p = 0.034), improved mental health (p<0.001), longer disease duration (p = 0.009), and better physical health at baseline (p = 0.027). Improved mental health after 6 months was associated with better family support (p = 0.002), improvements in physical health (p<0.001), disease activity, and prednisolone dose (interaction term p = 0.019), less disease related damage (p<0.001), non-use of cytotoxic drugs (p = 0.02), and older age at diagnosis (p = 0.007). CONCLUSION: Potentially modifiable psychosocial, disease, and therapy related factors influence QOL in patients with SLE.

Adolescent↗
PubMed1999

Validation of the medical outcomes study family and marital functioning measures in SLE patients in Singapore.

OBJECTIVE: To validate the Medical Outcomes Study Family and Marital Functioning Measures (FMM and MFM) in a multi-ethnic, urban Asian population in Singapore. METHODS: English speaking Chinese, Malay or Indian SLE patients (n=120) completed a self-administered questionnaire containing the FFM and MFM at baseline, after 2 weeks and after 6 months. Lupus activity, disease-related damage and quality of life were assessed using the British Isles Lupus Assessment Group (BILAG), Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) Damage Index and SF-36 Health Survey respectively. Scale psychometric properties were assessed through factor analysis, Cronbach's alpha, quantifying test-retest differences and known-groups construct validity. RESULTS: Factor analysis of scores obtained at baseline and after 6 months identified 3 factors corresponding to the FFM (1 factor) and the MFM (2 factors). Both scales showed acceptable internal consistency, with Cronbach's alpha of 0.95 for the FFM and 0.70 for the MFM. Mean (s.d.) test-retest differences were -0.31 (3.82) points for the FFM and -0.70 (4.26) points for the MFM. Eleven out of 13 a priori hypotheses relating both the FFM and MFM to demographic, disease and quality of life variables were confirmed, supporting the construct validity of these scales. CONCLUSION: The FFM and MFM are valid and reliable measures of family and marital functioning in a multi-ethnic cohort of Asian SLE patients in Singapore.

Adolescent↗
PubMed1999

The Rheumatology Attitudes Index and its helplessness subscale are valid and reliable measures of learned helplessness in Asian patients with systemic lupus erythematosus.

OBJECTIVE: To assess the internal consistency, reliability, and construct validity of the Rheumatology Attitudes Index (RAI) and its subscales in a cohort of Asian patients with systemic lupus erythematosus (SLE). METHODS: English speaking ethnic Chinese, Malay, or Indian patients with SLE (n = 120) seen at a rheumatology unit completed a questionnaire containing the RAI twice within a 2 week period. Lupus activity was assessed using the British Isles Lupus Activity Group (BILAG) score, disease related damage using the Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) damage index, and quality of life using the Medical Outcome Survey Short Form 36 Health Survey (SF-36). Factor analysis and Cronbach's alpha were used to study the psychometric properties of the RAI. The magnitude of test-retest differences was assessed using the method of Bland and Altman. Relationships between the RAI, its helplessness (HS) and internality (IS) subscales, and BILAG, SLICC/ACR damage index and SF-36 scores were studied using Spearman's rank correlation. RESULTS: Factor analysis (n = 105) identified 2 factors corresponding to the HS and IS subscales of the RAI. All scales showed acceptable internal consistency, with Cronbach's alpha of 0.64 for the HS, 0.77 for the IS, and 0.74 for the RAI. Mean (SD) test-retest differences were 0.85 (3.96) points for the HS (n = 86), 0.81 (4.44) points for the IS (n = 85), and 1.46 (7.88) points for the RAI (n = 74). Six of 10 hypotheses relating the RAI and HS to demographic, disease, and quality of life variables were confirmed, supporting the construct validity of these scales. CONCLUSION: The RAI and its helplessness subscale are valid and reliable measures of learned helplessness in a multiethnic cohort of Asian patients with SLE in Singapore.

Adolescent↗
PubMed1999

Validation of the MOS SF-36 for quality of life assessment of patients with systemic lupus erythematosus in Singapore.

OBJECTIVE: To assess the reliability and construct validity of the Medical Outcomes Study Short Form 36 Health Survey (SF-36) in a multiracial cohort of Asian patients with lupus in Singapore. METHODS: A cross sectional study was performed on 118 English speaking patients with lupus attending a specialist rheumatology unit between March and August 1996. Patients completed a questionnaire containing the UK standard version of the SF-36 twice within a 14 day period. All patients were assessed for disease activity using the British Isles Lupus Assessment Group score (BILAG), and for disease related damage using the Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) damage index (DI). Relationships between SF-36, BILAG, and DI scores were studied using Spearman's rank correlation. Internal consistency of the SF-36 was assessed using Cronbach's alpha, and stability using the repeatability coefficient of Bland and Altman. RESULTS: SF-36 subscales showed high internal consistency, with Cronbach's alpha coefficient ranging from 0.84 to 0.94. Test-retest reliability was acceptable, with Spearman's rank correlation >0.70 for all subscales except role-physical, and mean differences in test scores of <2 points for 5 of 8 subscales. SF-36 subscale scores were weakly correlated with BILAG scores (Spearman's p -0.37 to 0.15) and SLICC/ACR DI scores (Spearman's p -0.25 to 0.23), suggesting divergent construct validity of the SF-36. CONCLUSION: These data suggest the SF-36 is a reliable and valid measure of the quality of life of patients with lupus in Singapore.

Cohort Studies↗
PubMed1998

Ophthalmic manifestations in Asian patients with systemic lupus erythematosus.

AIM OF STUDY: To determine the spectrum and prevalence of ophthalmic manifestations of systemic lupus erythematosus (SLE) in Asian patients. METHODS: We performed a standardised ophthalmic examination on consecutive Asian patients with SLE referred from a tertiary rheumatology unit to an ophthalmology department. RESULTS: Seventy patients were included in the study. There were 66 females (94%) and 4 males (6%). The mean (range) age of the patients was 32.9 (9-67) years. Five patients (7%) had ophthalmic symptoms while 65 (93%) were asymptomatic. Eighty-three eyes of 45 patients had abnormal Schirmer's #1 test and 27 of these eyes of 17 patients also had concomitant rose bengal staining of the cornea and/or conjunctiva. Seventeen eyes of 9 patients had retinal vascular lesions. Fourteen of these eyes had mild microangiopathic retinopathy with best-corrected visual acuity (BCVA) 6/12 or better and 3 had retinal vaso-occlusive disease with BCVA worse than 6/12. Twenty-eight eyes of 14 patients had cataract and 3 eyes of 2 patients had raised intraocular pressure. Twelve eyes of 7 patients had BCVA worse than 6/12 because of optic neuropathy (4 eyes), posterior subscapsular cataract (4 eyes), retinal vaso-occlusive disease (3 eyes) and phthisis bulbi (1 eye). None had any eyelid lesion, extraocular motility disorder or retrochiasmal disorder of vision. CONCLUSIONS: Asymptomatic dry eye is the most common ocular finding in patients with SLE. Sight-threatening complications of SLE include retinal vaso-occlusive disease and optic neuropathy.

Adolescent↗
PubMed1998

Ankylosing spondylitis in Singapore: a study of 150 patients and a local update.

This paper presents the results of a clinical study of 150 patients in Singapore with ankylosing spondylitis (AS) and reviews recent developments locally with regards to the disease. The patients were predominantly males (ratio 7:1) and Chinese (n = 147). The onset of disease is usually in the early twenties and there was a mean delay of 6.3 years before diagnosis was made. Peripheral joint involvement is common but apart from uveitis (17%), extra-articular manifestations are rare. AS patients have abnormal lipid profiles and lower bone mineral density compared to healthy controls. HLA*B2704 is the predominant subtype in our Chinese patients whilst HLA*B2706 was found only in healthy controls. Intensive group physiotherapy is beneficial for patients with spondyloarthropathy.

Adolescent↗
PubMed1998

Clinical predictors of nephritis in systemic lupus erythematosus.

We identified clinical predictors of lupus nephritis presenting more than 6 months after the diagnosis of lupus in a cohort of 335 lupus patients. Almost 24% (80/335) of patients developed nephritis more than 6 months after the diagnosis of lupus. Using a Cox proportional hazards model, we found hypertension, thrombocytopaenia and leukopaenia to be associated with lupus nephritis presenting more than 6 months after diagnosis, with adjusted relative risks of 2.5 (95% CI 1.3 to 4.7), 4.3 (95% CI 1.7 to 10.8) and 3.2 (95% CI 1.7 to 6.2) respectively. In this cohort, hypertension, thrombocytopaenia and leukopaenia were associated with lupus nephritis presenting more than 6 months after the diagnosis of lupus.

Adult↗
PubMed1998

The sensitivity and specificity of autoantibodies to the Sm antigen in the diagnosis of systemic lupus erythematosus.

The anti-Sm test is thought to be specific for the diagnosis of systemic lupus erythematosus (SLE) and is one of the American College for Rheumatology (ACR) criteria for the classification of SLE. Locally, the sensitivity and specificity of this test for the diagnosis of SLE are unknown. We therefore aim to study the sensitivity and specificity of this test in our local context. A total of 1034 patient samples that were sent for routine testing of anti-Sm antibodies over a 30-month period, were included in the study. However, only 1031 patient samples were included in the final analysis as 3 casenotes were not traceable. Clinical diagnoses were obtained through a lupus database and chart review. Quantification of the anti-Sm antibodies was by the enzyme-linked immunosorbent assay (ELISA) technique. Positive anti-Sm test results were present in 165 samples, comprising 156 (94.5%) samples from lupus patients and 9 (5.5%) having diagnoses other than SLE. These diagnoses ranged from arthritis, overlap syndrome, Raynaud's phenomenon and cardiac-related diseases. The calculated sensitivity and specificity of the anti-Sm test, using a positive cut-off value of 20 units/ml, were 39.7% and 98.6%, respectively. If the positive cut-off value is raised to 30 units/ml, the specificity rises marginally to 99.5% but the sensitivity will drop by more than 10 percentage points to 27.2%. The anti-Sm test is not useful as a screening test for lupus but a positive result is highly specific for SLE.

Antigen-Antibody Reactions↗
PubMed1998

Systemic lupus erythematosus in Singapore.

The major initial clinical manifestations of systemic lupus erythematousus (SLE) were skin and mucous membrane involvement (52%), fever and malaise (48%), arthritis and arthralgias (44%). Lupus nephritis was diagnosed in 74% of patients and diffuse proliferative nephritis was the commonest histologic picture encountered. Except for a higher prevalence of anti-SS-A (Ro) (63%), other autoantibodies were within the normal range reported from Western countries. There was no significant association between HLA-A, B or DR specificities in 51 Chinese patients, nor was there any differences seen in the polymorphism of tumour necrosis factor alpha gene (TNF-alpha). Arthritis was less commonly seen in males with SLE. Prevalences of leukopenia and antibodies to anti-SS-A (Ro) and anti-La (SS-B) antigens were lower in men. Late onset lupus patients (> 50 years of age) tended to have more insidious onset of disease, lower female predominance and less frequent complaints of fever, alopecia, arthritis and malar rash at presentation. The causes of death were often treatment related. Survival studies among 183 SLE patients during the period from 1970 to 1980 revealed a 5- and 10-year survival rate of 70% and 60%, respectively. Infections and active lupus disease were 2 major causes of death. Research into SLE is targeted at increasing our understanding of the disease process and improving outcome and prognosis.

Adolescent↗