1.A practical guide for multivariate analysis of dichotomous outcomes.
James LEE ; Chuen Seng TAN ; Kee Seng CHIA
Annals of the Academy of Medicine, Singapore 2009;38(8):714-719
A dichotomous (2-category) outcome variable is often encountered in biomedical research, and Multiple Logistic Regression is often deployed for the analysis of such data. As Logistic Regression estimates the Odds Ratio (OR) as an effect measure, it is only suitable for case-control studies. For cross-sectional and time-to-event studies, the Prevalence Ratio and Cumulative Incidence Ratio can be estimated and easily interpreted. The logistic regression will produce the OR which is difficult to interpret in these studies. In this report, we reviewed 3 alternative multivariate statistical models to replace Logistic Regression for the analysis of data from cross-sectional and time-to-event studies, viz, Modified Cox Proportional Hazard Regression Model, Log-Binomial Regression Model and Poisson Regression Model incorporating the Robust Sandwich Variance. Although none of the models is without flaws, we conclude the last model is the most viable. A numeric example is given to compare the statistical results obtained from all 4 models.
Cross-Sectional Studies
;
Humans
;
Incidence
;
Models, Statistical
;
Multivariate Analysis
;
Odds Ratio
;
Outcome Assessment (Health Care)
;
methods
;
Poisson Distribution
;
Prevalence
;
Proportional Hazards Models
;
Risk
;
Risk Assessment
3.Surgeon-Performed Ultrasound-Guided Fine-Needle Aspiration Cytology (SP-US-FNAC) Shortens Time for Diagnosis of Thyroid Nodules.
Wei Xiang GU ; Chuen Seng TAN ; Thomas W T HO
Annals of the Academy of Medicine, Singapore 2014;43(6):320-324
INTRODUCTIONUltrasound-guided fine-needle aspiration cytology (US-FNAC) of thyroid nodules is an important diagnostic procedure. In most hospitals, patients are referred to radiologists for US-FNAC, but this often results in a long waiting time before results are available. Surgeon-performed US-FNAC (SP-US-FNAC) during the initial patient consultation attempts to reduce the waiting time but it is not known whether this is as accurate as radiologist-performed US-FNAC (RP-US-FNAC). The aim of this study is to compare the clinical efficiency between SP-US-FNAC and RP-US-FNAC.
MATERIALS AND METHODSA retrospective study was performed on patients from the Department of General Surgery, Tan Tock Seng Hospital (TTSH) who underwent an US-FNAC from August 2011 to May 2012. All cases of SP-US-FNAC were performed by a single surgeon. This study compared the rates of positive diagnoses achieved by SP-US-FNAC and RPUS- FNAC as well as the time interval to reach a cytological diagnosis by each group.
RESULTSA total of 40 cases of SP-US-FNAC and 72 cases of RP-US-FNAC were included in the study. SP-US-FNAC resulted in 28 (70%) positive diagnoses and 12 (30%) nondiagnoses while RP-US-FNAC resulted in 47 (65.3%) positive diagnoses and 25 (34.7%) non-diagnoses. These results were comparable (P=0.678). The median time taken to reach a cytological diagnosis was 1 working day for SP-US-FNAC and 29.5 working days for RP-US-FNAC resulting in a shorter interval to reaching a cytological diagnosis for SP-US-FNAC (P<0.001).
CONCLUSIONIn the workup of thyroid nodules, SP-US-FNAC is as accurate as RP-US-FNAC but significantly reduces the time taken to reach a cytological diagnosis. This leads to greater clinical efficiency in the management of patients with thyroid nodules, which in turn leads to other benefits such as decreased patient anxiety and increased patient satisfaction.
Adult ; Biopsy, Fine-Needle ; methods ; Female ; Humans ; Image-Guided Biopsy ; Male ; Middle Aged ; Retrospective Studies ; Specialties, Surgical ; Thyroid Nodule ; pathology ; Time Factors
4.Incidence, mortality and five-year relative survival ratio of prostate cancer among Chinese residents in Singapore from 1968 to 2002 by metastatic staging.
Sin Eng CHIA ; Chuen Seng TAN ; Gek Hsiang LIM ; Xueling SIM ; Weber LAU ; Kee Seng CHIA
Annals of the Academy of Medicine, Singapore 2010;39(6):466-471
INTRODUCTIONThis paper examines the incidence, mortality and survival patterns among all Chinese residents with prostate cancer reported to the Singapore Cancer Registry in Singapore from 1968 to 2002 by metastatic staging.
MATERIALS AND METHODSThis is a retrospective population-based study including all prostate cancer cases aged over 20 reported to the Singapore Cancer Registry (SCR) from 1968 to 2002 who are Singapore Chinese residents. Follow-up was ascertained by matching with the National Death Register until 2002. Metastatic status was obtained from the SCR. Age-standardised incidence and mortality rates, as well as the 5-year relative survival ratios (RSRs), were obtained for each 5-year period and grouped by metastatic stage. A weighted linear regression was performed on the log-transformed age-standardised incidence and mortality rates over the study period.
RESULTSIn the most recent period of 1998 to 2002, the age-standardised incidence and mortality rates (per 100,000) for prostate cancer among the Chinese were 30.9 (95% CI, 29.1 to 32.8) and 9.6 (95% CI, 8.6 to 10.7), respectively. The percentage increase in the age-standardised incidence and age-standardised mortality rates per year were 5.6% and 6.0%, respectively, for all Chinese Singapore residents. There was an improvement in the 5-year RSRs for Chinese diagnosed with non-metastatic cases from 51.3% in 1973 to 1977, to 76.1% in 1998 to 2002. However, the RSR remains poor (range, 11.1% to 49.7%) for Chinese diagnosed with metastatic prostate cancer.
CONCLUSIONSBoth age-standardised incidence and mortality rates for prostate cancer among Chinese Singapore residents are still on the rise especially since the 1990s. Since the 1990s, the improvement in RSRs was substantial for the Chinese non-metastatic cases.
Adult ; Aged ; Aged, 80 and over ; China ; epidemiology ; ethnology ; Humans ; Male ; Middle Aged ; Neoplasm Metastasis ; diagnosis ; Prostatic Neoplasms ; epidemiology ; ethnology ; mortality ; Registries ; Retrospective Studies ; Singapore ; epidemiology ; Survival Rate ; trends ; Young Adult
5.Severe COVID-19 and coagulopathy: A systematic review and meta-analysis.
Saikat MITRA ; Ryan Ruiyang LING ; Isabelle Xiaorui YANG ; Wynne Hsing POON ; Chuen Seng TAN ; Paul MONAGLE ; Graeme MACLAREN ; Kollengode RAMANATHAN
Annals of the Academy of Medicine, Singapore 2021;50(4):325-335
INTRODUCTION:
Coronavirus disease 2019 (COVID-19)-induced coagulopathy (CIC) has been widely reported in the literature. However, the spectrum of abnormalities associated with CIC has been highly variable.
METHODS:
We conducted a systematic review of the literature (until 1 June 2020) to assess CIC and disease severity during the early COVID-19 pandemic. Primary outcomes were pooled mean differences in platelet count, D-dimer level, prothrombin time, activated partial thromboplastin time (aPTT) and fibrinogen level between non-severe and severe patients, stratified by degree of hypoxaemia or those who died. The risk factors for CIC were analysed. Random-effects meta-analyses and meta-regression were performed using R version 3.6.1, and certainty of evidence was rated using the Grading of Recommendation, Assessment, Development, and Evaluation approach.
RESULTS:
Of the included 5,243 adult COVID-19 patients, patients with severe COVID-19 had a significantly lower platelet count, and higher D-dimer level, prothrombin time and fibrinogen level than non-severe patients. Pooled mean differences in platelet count (-19.7×109/L, 95% confidence interval [CI] -31.7 to -7.6), D-dimer level (0.8μg/mL, 95% CI 0.5-1.1), prothrombin time (0.4 second, 95% CI 0.2-0.6) and fibrinogen level (0.6g/L, 95% CI 0.3-0.8) were significant between the groups. Platelet count and D-dimer level were significant predictors of disease severity on meta-regression analysis. Older men had higher risks of severe coagulopathic disease.
CONCLUSION
Significant variability in CIC exists between non-severe and severe patients, with platelet count and D-dimer level correlating with disease severity. Routine monitoring of all coagulation parameters may help to assess CIC and decide on the appropriate management.
6.Clinical Prevalence and Associated Factors of Erectile Dysfunction in Patients Undergoing Haemodialysis.
Lang Chu LAU ; P Ganesan ADAIKAN ; Anantharaman VATHSALA ; Balasubramanian SRILATHA ; Mee Lian WONG ; Chuen Seng TAN ; Xiaodong DENG ; Hersharan Kaur SRAN ; Lee Hwee KOH ; Valerie MA
Annals of the Academy of Medicine, Singapore 2018;47(2):78-81
7.Epidemiological and pathophysiological evidence supporting links between obstructive sleep apnoea and Type 2 diabetes mellitus.
Chuen Peng LEE ; Clete A KUSHIDA ; John Arputhan ABISHEGANADEN
Singapore medical journal 2019;60(2):54-56
Obstructive sleep apnoea (OSA) and Type 2 diabetes mellitus (T2DM) are common diseases. The global prevalence of OSA is between 2% and 7% in general population cohorts. The worldwide prevalence of T2DM among adults (aged 20-79 years) was estimated to be 6.4%. The concurrent presence of OSA and T2DM can be expected in the same patient, given their high prevalence and similar predisposition. We reviewed the overlapping pathophysiology of OSA and T2DM in this article.
Adult
;
Aged
;
Continuous Positive Airway Pressure
;
Diabetes Mellitus, Type 2
;
complications
;
epidemiology
;
physiopathology
;
Female
;
Humans
;
Male
;
Middle Aged
;
Sleep Apnea, Obstructive
;
complications
;
epidemiology
;
physiopathology
;
therapy
;
Young Adult
8.Merits of a harmonised system to classify drug-related problems in Singapore.
Tat Ming NG ; Wee Chuan HING ; Tsing Yi KOH ; Wei Terk CHANG ; Grace S W CHANG ; Jian Wei HENG ; Isnarti Bte ABUAMAN ; Beng Yi SIA ; Yik Chuen SAW ; Daphne CHAN ; Chwee Huat TAN ; Wei Shan FAN ; Franky FRANKY ; Poh Ching TAN ; Cheryl W Y TAN ; Joanne H L SNG ; Chun Wei YAP ; Shanti Uma Devi GNANAMANI ; Doreen S Y TAN
Annals of the Academy of Medicine, Singapore 2021;50(7):572-577
9.A systematic review of the association of obesity with the outcomes of inflammatory rheumatic diseases.
Yi Xuan LEE ; Yu Heng KWAN ; Ka Keat LIM ; Chuen Seng TAN ; Nai Lee LUI ; Jie Kie PHANG ; Eng Hui CHEW ; Truls OSTBYE ; Julian THUMBOO ; Warren FONG
Singapore medical journal 2019;60(6):270-280
This was a systematic review of the literature on the association between obesity and the outcome of inflammatory rheumatic diseases. We conducted a literature search using PubMed®, Embase and PsycINFO®. Articles were classified into three categories based on the effects of obesity on the outcomes of inflammatory rheumatic diseases. The subject population, country, type of studies, number of patients, measurement of obesity and outcomes assessed were presented. Quality was appraised using Kmet et al's criteria. 4,331 articles were screened and 60 were relevant to the objective. Obesity had a negative, positive and neutral association with outcomes of inflammatory rheumatic diseases in 38 (63.3%) studies with 57,612 subjects, 11 (18.3%) studies with 3,866 subjects, and 11 (18.3%) studies with 3,834 subjects, respectively. In most studies, the disease population had been diagnosed with rheumatoid arthritis (RA). Tumour necrosis factor-α inhibitors were mostly associated with negative outcomes. More studies examining subjects outside Europe and North America and diseases other than RA are warranted.
10.Body mass index and the risk of postoperative cerebrospinal fluid leak following transsphenoidal surgery in an Asian population.
Ira SUN ; Jia Xu LIM ; Chun Peng GOH ; Shiong Wen LOW ; Ramez W KIROLLOS ; Chuen Seng TAN ; Sein LWIN ; Tseng Tsai YEO
Singapore medical journal 2018;59(5):257-263
INTRODUCTIONPostoperative cerebrospinal fluid (CSF) leak is a serious complication following transsphenoidal surgery for which elevated body mass index (BMI) has been implicated as a risk factor, albeit only in two recent North American studies. Given the paucity of evidence, we sought to determine if this association holds true in an Asian population, where the BMI criteria for obesity differ from the international standard.
METHODSA retrospective study of 119 patients who underwent 123 transsphenoidal procedures for sellar lesions between May 2000 and May 2012 was conducted. Univariate and multivariate logistic regression analyses were performed to investigate the impact of elevated BMI and other risk factors on postoperative CSF leak.
RESULTS10 (8.1%) procedures in ten patients were complicated by postoperative CSF leak. The median BMI of patients with postoperative leak following transsphenoidal procedures was significantly higher than that of patients without postoperative CSF leak (27.0 kg/m vs. 24.6 kg/m; p = 0.018). Patients categorised as either moderate or high risk under the Asian BMI classification were more likely to suffer from a postoperative leak (p = 0.030). Repeat procedures were also found to be significantly associated with postoperative CSF leak (p = 0.041).
CONCLUSIONElevated BMI is predictive of postoperative CSF leak following transsphenoidal procedures, even in an Asian population, where the definition of obesity differs from international standards. Thus, BMI should be considered in the clinical decision-making process prior to such procedures.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Anthropometry ; Asian Continental Ancestry Group ; Body Mass Index ; Body Weight ; Cerebrospinal Fluid Leak ; diagnosis ; Cerebrospinal Fluid Rhinorrhea ; diagnosis ; Female ; Humans ; Male ; Middle Aged ; Multivariate Analysis ; Neurosurgical Procedures ; adverse effects ; Obesity ; classification ; Postoperative Complications ; Postoperative Period ; Regression Analysis ; Retrospective Studies ; Risk Factors ; Singapore ; Young Adult