Displaying publications 1 - 20 of 189 in total

  1. Fang YY, Suraiya Kassim
    Sains Malaysiana, 2013;42:673-683.
    In competing risks analysis, the primary interest of researchers is the estimation of the net survival probability (NSP) if a cause of failure could be eliminated from a population. The Kaplan-Meier product-limit estimator under the assumption that the eliminated risk is non-informative to the other remaining risks, has been widely used in the estimation of the NSP. The assumption implies that the hazard of the remaining risks before and after the elimination are equal and it could be biased. This paper addressed this possible bias by proposing a non-parametric multistate approach that accounts for an informative eliminated risk in the estimation procedure, whereby the hazard probabilities of the remaining risks before and after the elimination of a risk are not assumed to be equal. When a non-informative eliminated risk was assumed, it was shown that the proposed multistate estimator reduces to the Kaplan-Meier estimator. For illustration purposes, the proposed procedure was implemented on a published dataset and the change in hazard after elimination of a cause is investigated. Comparing the results to those obtained from using the Kaplan-Meier method, it was found that in the presence of (both constant and non-constant) informative eliminated risk, the proposed multistate approach was more sensitive and flexible.
    Matched MeSH terms: Survival Analysis
  2. Bader Ahmad Aljawadi, Mohd Rizam Abu Bakar, Noor Akma
    This study deals with the analysis of the cure rate estimation based on the Bounded Cumulative Hazard (BCH) model using interval censored data, given that the exact distribution of the data set is unknown. Thus, the non-parametric estimation methods are employed by means of the EM algorithm. The Turnbull and Kaplan Meier estimators were proposed to estimate the survival function, even though the Kaplan Meier estimator faces some restrictions in term of interval survival data. A comparison of the cure rate estimation based on the two estimators was done through a simulation study.
    Matched MeSH terms: Survival Analysis
  3. Kiani K, Arasan J, Habshah Midi
    Sains Malaysiana, 2012;41:471-480.
    There are numerous parametric models for analyzing survival data such as exponential, Weibull, log-normal and gamma. One of such models is the Gompertz model which is widely used in biology and demography. Most of these models are extended to new forms for accommodating different types of censoring mechanisms and different types of covariates. In this paper the performance of the Gompertz model with time-dependent covariate in the presence of right censored data was studied. Moreover, the performance of the model was compared at different censoring proportions (CP) and sample sizes. Also, the model was compared with fixed covariate model. In addition, the effect of fitting a fixed covariate model wrongly to a data with time-dependent covariate was studied. Finally, two confidence interval estimation techniques, Wald and jackknife, were applied to the parameters of this model and the performance of the methods was compared.
    Matched MeSH terms: Survival Analysis
  4. Phang KC, Hussin NH, Abdul Rahman F, Tizen NMS, Mansoor A, Masir N
    Malays J Pathol, 2019 Aug;41(2):101-124.
    PMID: 31427546
    INTRODUCTION: Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive type of non-Hodgkin lymphoma with variable clinical outcomes. The immunogenotypic features of this heterogeneous disease in Malaysia were not well characterized.

    MATERIALS & METHODS: In total 141 local series of DLBCL cases from UKM Medical Centre were retrospectively studied.

    RESULTS: Of these cases, we classified our patients into two subtypes: 32.7% (37/113) GCB and non-GCB 67.3% (76/113) by Hans algorithm and the results showed strong agreement with the results by Choi algorithm (κ = 0.828, P<0.001). Survival analysis indicated significant difference in between GCB and non-GCB subtypes (P=0.01), elevated serum LDH (P=0.016), age more than 60-year-old (P=0.021) and the presence of B symptoms (P=0.04). We observed 12% DLBCL cases were CD5 positive and 81.8% of them died of the disease (P=0.076). Analysis on the dual expression of MYC/BCL2 revealed that there is no significant difference in DE and non-DE groups (P=0.916). FISH study reported there were 9.22% (13/141) rearranged cases observed in our population at which highest frequency of BCL6 gene rearrangement (76.9%), followed by MYC (15.4%) and BCL2 (7.7%); no BCL10 and MALT-1 gene rearrangement found regardless of using TMAs or whole tissue samples. More cases of MYC protein overexpression observed compared to MYC translocation.

    CONCLUSION: Relatively lower frequency of GCB tumours and low gene rearrangement rates were observed in Malaysian population. A national study is therefore warranted to know better the immunogenotypic characteristics of DLBCL in Malaysia and their implications on the survival.

    Matched MeSH terms: Survival Analysis
  5. Kong YC, Bhoo-Pathy N, Subramaniam S, Bhoo-Pathy N, Taib NA, Jamaris S, et al.
    PMID: 28420149 DOI: 10.3390/ijerph14040427
    Background: Survival disparities in cancer are known to occur between public and private hospitals. We compared breast cancer presentation, treatment and survival between a public academic hospital and a private hospital in a middle-income country. Methods: The demographics, clinical characteristics, treatment and overall survival (OS) of 2767 patients with invasive breast carcinoma diagnosed between 2001 and 2011 in the public hospital were compared with 1199 patients from the private hospital. Results: Compared to patients in the private hospital, patients from the public hospital were older at presentation, and had more advanced cancer stages. They were also more likely to receive mastectomy and chemotherapy but less radiotherapy. The five-year OS in public patients was significantly lower than in private patients (71.6% vs. 86.8%). This difference was largely attributed to discrepancies in stage at diagnosis and, although to a much smaller extent, to demographic differences and treatment disparities. Even following adjustment for these factors, patients in the public hospital remained at increased risk of mortality compared to their counterparts in the private hospital (Hazard Ratio: 1.59; 95% Confidence Interval: 1.36-1.85). Conclusion: Late stage at diagnosis appears to be a major contributing factor explaining the breast cancer survival disparity between public and private patients in this middle-income setting.
    Matched MeSH terms: Survival Analysis*
  6. Guure CB, Ibrahim NA, Adam MB
    Comput Math Methods Med, 2013;2013:849520.
    PMID: 23476718 DOI: 10.1155/2013/849520
    Interval-censored data consist of adjacent inspection times that surround an unknown failure time. We have in this paper reviewed the classical approach which is maximum likelihood in estimating the Weibull parameters with interval-censored data. We have also considered the Bayesian approach in estimating the Weibull parameters with interval-censored data under three loss functions. This study became necessary because of the limited discussion in the literature, if at all, with regard to estimating the Weibull parameters with interval-censored data using Bayesian. A simulation study is carried out to compare the performances of the methods. A real data application is also illustrated. It has been observed from the study that the Bayesian estimator is preferred to the classical maximum likelihood estimator for both the scale and shape parameters.
    Matched MeSH terms: Survival Analysis*
  7. Go KW, Teo SM
    Transplant. Proc., 2004 Sep;36(7):2046-7.
    PMID: 15518740
    To compare patient graft survival between various subgroups among renal transplant patients.
    Matched MeSH terms: Survival Analysis*
  8. Szulkin R, Karlsson R, Whitington T, Aly M, Gronberg H, Eeles RA, et al.
    Cancer Epidemiol Biomarkers Prev, 2015 Nov;24(11):1796-800.
    PMID: 26307654 DOI: 10.1158/1055-9965.EPI-15-0543
    BACKGROUND: Unnecessary intervention and overtreatment of indolent disease are common challenges in clinical management of prostate cancer. Improved tools to distinguish lethal from indolent disease are critical.

    METHODS: We performed a genome-wide survival analysis of cause-specific death in 24,023 prostate cancer patients (3,513 disease-specific deaths) from the PRACTICAL and BPC3 consortia. Top findings were assessed for replication in a Norwegian cohort (CONOR).

    RESULTS: We observed no significant association between genetic variants and prostate cancer survival.

    CONCLUSIONS: Common genetic variants with large impact on prostate cancer survival were not observed in this study.

    IMPACT: Future studies should be designed for identification of rare variants with large effect sizes or common variants with small effect sizes.

    Matched MeSH terms: Survival Analysis
  9. Tay JW, Lee CY
    Trop Biomed, 2015 Sep;32(3):453-62.
    PMID: 26695205 MyJurnal
    To evaluate the effects of the juvenile hormone analogue pyriproxyfen on colonies of the Pharaoh ant Monomorium pharaonis (L.), peanut oil containing different concentrations (0.3, 0.6, or 0.9%) of pyriproxyfen was fed to monogynous (1 queen, 500 workers, and 0.1 g of brood) and polygynous (8 queens, 50 workers, and 0.1 g of brood) laboratory colonies of M. pharaonis. Due to its delayed activity, pyriproxyfen at all concentrations resulted in colony elimination. Significant reductions in brood volume were recorded at weeks 3 - 6, and complete brood mortality was observed at week 8 in all treated colonies. Brood mortality was attributed to the disruption of brood development and cessation of egg production by queens. All polygynous colonies exhibited significant reduction in the number of queens present at week 10 compared to week 1. Number of workers was significantly lower in all treated colonies compared to control colonies at week 8 due to old-age attrition of the workers without replacement. At least 98.67 ± 1.33% of workers were dead at week 10 in all treated colonies. Thus, treatment with slow acting pyriproxyfen at concentrations of 0.3 - 0.9% is an effective strategy for eliminating Pharaoh ant colonies.
    Matched MeSH terms: Survival Analysis
  10. Loke SR, Sing KW, Teoh GN, Lee HL
    Trop Biomed, 2015 Mar;32(1):76-83.
    PMID: 25801256 MyJurnal
    Space spraying of chemical insecticides is still an important mean of controlling Aedes mosquitoes and dengue transmission. For this purpose, the bioefficacy of space-sprayed chemical insecticide should be evaluated from time to time. A simulation field trial was conducted outdoor in an open field and indoor in unoccupied flat units in Kuala Lumpur, to evaluate the adulticidal and larvicidal effects of Sumithion L-40, a ULV formulation of fenitrothion. A thermal fogger with a discharge rate of 240 ml/min was used to disperse Sumithion L-40 at 3 different dosages (350 ml/ha, 500 ml/ha, 750 ml/ha) against lab-bred larvae and adult female Aedes aegypti and Aedes albopictus. An average of more than 80% adult mortality was achieved for outdoor space spray, and 100% adult mortality for indoor space spray, in all tested dosages. Outdoor larvicidal effect was noted up to 14 days and 7 days at a dosage of 500 and 750 ml/ha for Ae. aegypti and Ae. albopictus, respectively. Indoor larvicidal effect was up to 21 days (500 ml/ha) and 14 days (750 ml/ha), respectively, after spraying with larval mortality > 50% against Ae. aegypti. This study concluded that the effective dosage of Sumithion L-40 thermally applied against adult Ae. aegypti and Ae. albopictus indoor and outdoor is 500 and 750 ml/ha. Based on these dosages, effective indoor spray volume is 0.4 - 0.6 ml/m³. Additional indoor and outdoor larvicidal effect will be observed at these application dosages, in addition to adult mortality.
    Matched MeSH terms: Survival Analysis
  11. Thomas R, Hamat RA, Neela V
    J. Med. Microbiol., 2013 Nov;62(Pt 11):1777-1779.
    PMID: 23988629 DOI: 10.1099/jmm.0.063230-0
    Matched MeSH terms: Survival Analysis
  12. Dieng H, Rajasaygar S, Ahmad AH, Ahmad H, Rawi CS, Zuharah WF, et al.
    Acta Trop, 2013 Dec;128(3):584-90.
    PMID: 23999373 DOI: 10.1016/j.actatropica.2013.08.013
    Annually, 4.5 trillion cigarette butts (CBs) are flicked into our environment. Evidence exists that CB waste is deadly to aquatic life, but their lethality to the aquatic life of the main dengue vector is unknown. CBs are full of toxicants that occur naturally, during planting and manufacturing, which may act as larvicidal agents. We assessed Aedes aegypti vulnerability to Marlboro butts during its development. Overall, CBs showed insecticidal activities against larvae. At early phases of development, mortality rates were much higher in two CBs solution (2CBSol) and 3CBSol microcosms (MICRs). Larval survival gradually decreased with development in 1CBSol-MICRs. However, in great presence of CBs, mortality was high even for the late developmental stages. These results suggest that A. aegypti larvae are vulnerable to CB presence in their habitats, but this effect was seen most during the early developmental phases and in the presence of increased amounts of cigarette remnants. CB filters are being used as raw material in many sectors, i.e., brick, art, fashion, plastic industries, as a practical solution to the pollution problem, the observed butt waste toxicity to mosquito larvae open new avenues for the identification of novel insecticide products.
    Matched MeSH terms: Survival Analysis
  13. Mohammed R, Goh KL, Wong NW
    Med J Malaysia, 1996 Mar;51(1):99-102.
    PMID: 10967987
    Primary biliary cirrhosis is an uncommon disease amongst Malaysians. Over a 12-year period, between 1979 and 1991, only seven patients with clinical, biochemical and histologic evidence of primary biliary cirrhosis were identified in University Hospital Kuala Lumpur. All were Chinese females between the ages of 30 to 55 years. The presenting complaint was pruritus in 5 patients. All except one patient was jaundiced when the diagnosis was made. These patients were followed up from 1 to 11 years. Three deaths were reported, one from massive hemetemesis and two from liver failure.
    Matched MeSH terms: Survival Analysis
  14. Santika T, Ancrenaz M, Wilson KA, Spehar S, Abram N, Banes GL, et al.
    Sci Rep, 2017 07 07;7(1):4839.
    PMID: 28687788 DOI: 10.1038/s41598-017-04435-9
    For many threatened species the rate and drivers of population decline are difficult to assess accurately: species' surveys are typically restricted to small geographic areas, are conducted over short time periods, and employ a wide range of survey protocols. We addressed methodological challenges for assessing change in the abundance of an endangered species. We applied novel methods for integrating field and interview survey data for the critically endangered Bornean orangutan (Pongo pygmaeus), allowing a deeper understanding of the species' persistence through time. Our analysis revealed that Bornean orangutan populations have declined at a rate of 25% over the last 10 years. Survival rates of the species are lowest in areas with intermediate rainfall, where complex interrelations between soil fertility, agricultural productivity, and human settlement patterns influence persistence. These areas also have highest threats from human-wildlife conflict. Survival rates are further positively associated with forest extent, but are lower in areas where surrounding forest has been recently converted to industrial agriculture. Our study highlights the urgency of determining specific management interventions needed in different locations to counter the trend of decline and its associated drivers.
    Matched MeSH terms: Survival Analysis
  15. Landoni G, Lomivorotov V, Pisano A, Nigro Neto C, Benedetto U, Biondi Zoccai G, et al.
    Contemp Clin Trials, 2017 08;59:38-43.
    PMID: 28533194 DOI: 10.1016/j.cct.2017.05.011
    OBJECTIVE: There is initial evidence that the use of volatile anesthetics can reduce the postoperative release of cardiac troponin I, the need for inotropic support, and the number of patients requiring prolonged hospitalization following coronary artery bypass graft (CABG) surgery. Nevertheless, small randomized controlled trials have failed to demonstrate a survival advantage. Thus, whether volatile anesthetics improve the postoperative outcome of cardiac surgical patients remains uncertain. An adequately powered randomized controlled trial appears desirable.

    DESIGN: Single blinded, international, multicenter randomized controlled trial with 1:1 allocation ratio.

    SETTING: Tertiary and University hospitals.

    INTERVENTIONS: Patients (n=10,600) undergoing coronary artery bypass graft will be randomized to receive either volatile anesthetic as part of the anesthetic plan, or total intravenous anesthesia.

    MEASUREMENTS AND MAIN RESULTS: The primary end point of the study will be one-year mortality (any cause). Secondary endpoints will be 30-day mortality; 30-day death or non-fatal myocardial infarction (composite endpoint); cardiac mortality at 30day and at one year; incidence of hospital re-admission during the one year follow-up period and duration of intensive care unit, and hospital stay. The sample size is based on the hypothesis that volatile anesthetics will reduce 1-year unadjusted mortality from 3% to 2%, using a two-sided alpha error of 0.05, and a power of 0.9.

    CONCLUSIONS: The trial will determine whether the simple intervention of adding a volatile anesthetic, an intervention that can be implemented by all anesthesiologists, can improve one-year survival in patients undergoing coronary artery bypass graft surgery.

    Matched MeSH terms: Survival Analysis
  16. Bhoo-Pathy NT, Inaida S, Tanaka S, Taib NA, Yip CH, Saad M, et al.
    Cancer Epidemiol, 2017 06;48:56-61.
    PMID: 28371729 DOI: 10.1016/j.canep.2017.03.007
    BACKGROUND: The benefit of adjuvant chemotherapy in women with T1N0M0 breast cancers is unclear. While gene expression-based prognostic assays may aid management of women with early estrogen receptor (ER) positive tumors, therapeutic decision-making in women with early stage ER negative tumors remains fraught with difficulties. We investigated the association between adjuvant chemotherapy and overall survival in women with T1N0M0, hormone receptor negative breast cancers.

    METHOD: All newly diagnosed breast cancer patients with node-negative and hormone receptor negative tumors measuring≤2cm at the University Malaya Medical Centre (Malaysia) from 1993 to 2013 were included. Mortality of patients with and without adjuvant chemotherapy were compared and adjusted for possible confounders using propensity score.

    RESULTS: Of 6732 breast cancer patients, 341 (5.1%) had small (≤2cm), node-negative and hormone receptor negative tumors at diagnosis. Among them, only 214 (62.8%) received adjuvant chemotherapy. Five-year overall survival was 88.1% (95% confidence interval (CI): 82.0%-94.2%) for patients receiving chemotherapy and 89.6% (95% CI: 85.1%-94.1%) for patients without chemotherapy. Chemotherapy was not associated with survival following adjustment for age, ethnicity, tumor size, tumor grade, HER2 status, lympho-vascular invasion, type of surgery and radiotherapy administration. However, chemotherapy was associated with a significant survival advantage (adjusted hazard ratio: 0.35, 95%CI: 0.14-0.91) in a subgroup of women with high-grade tumors.

    CONCLUSION: Adjuvant chemotherapy does not appear to be associated with a survival benefit in women with T1N0M0, hormone receptor negative breast cancer except in those with high-grade tumors.

    Matched MeSH terms: Survival Analysis
  17. Choudhury A, Jindal A, Maiwall R, Sharma MK, Sharma BC, Pamecha V, et al.
    Hepatol Int, 2017 Sep;11(5):461-471.
    PMID: 28856540 DOI: 10.1007/s12072-017-9816-z
    BACKGROUND AND AIMS: Acute-on-chronic liver failure (ACLF) is a progressive disease associated with rapid clinical worsening and high mortality. Early prediction of mortality and intervention can improve patient outcomes. We aimed to develop a dynamic prognostic model and compare it with the existing models.

    METHODS: A total of 1402 ACLF patients, enrolled in the APASL-ACLF Research Consortium (AARC) with 90-day follow-up, were analyzed. An ACLF score was developed in a derivation cohort (n = 480) and was validated (n = 922).

    RESULTS: The overall survival of ACLF patients at 28 days was 51.7%, with a median of 26.3 days. Five baseline variables, total bilirubin, creatinine, serum lactate, INR and hepatic encephalopathy, were found to be independent predictors of mortality, with AUROC in derivation and validation cohorts being 0.80 and 0.78, respectively. AARC-ACLF score (range 5-15) was found to be superior to MELD and CLIF SOFA scores in predicting mortality with an AUROC of 0.80. The point scores were categorized into grades of liver failure (Gr I: 5-7; II: 8-10; and III: 11-15 points) with 28-day cumulative mortalities of 12.7, 44.5 and 85.9%, respectively. The mortality risk could be dynamically calculated as, with each unit increase in AARC-ACLF score above 10, the risk increased by 20%. A score of ≥11 at baseline or persisting in the first week was often seen among nonsurvivors (p = 0.001).

    CONCLUSIONS: The AARC-ACLF score is easy to use, dynamic and reliable, and superior to the existing prediction models. It can reliably predict the need for interventions, such as liver transplant, within the first week.

    Matched MeSH terms: Survival Analysis
  18. Mohd Suan MA, Tan WL, Soelar SA, Ismail I, Abu Hassan MR
    Epidemiol Health, 2015;37:e2015017.
    PMID: 25868638 DOI: 10.4178/epih/e2015017
    OBJECTIVES: The goal of this study was to assess the relationship between intestinal obstruction and the prognosis of colorectal carcinoma.

    METHODS: Data pertaining to 4,501 colorectal carcinoma patients were extracted from the national colorectal registry and analysed. Survival analysis was performed using the Kaplan-Meier method. The log-rank test was used to compare the survival rate between patients with intestinal obstruction and those without intestinal obstruction. The p-values<0.05 were considered to indicate statistical significance. Simple Cox proportional hazards regression analysis was used to estimate the crude hazard ratio of mortality from colorectal cancer.

    RESULTS: Intestinal obstruction was reported in more than 13% of patients. The 3-year survival rate after treatment was 48.3% (95% confidence interval [CI], 43.9 to 52.8) for patients with intestinal obstruction (n=593) and 54.9% (95% CI, 53.1 to 56.6) for patients without intestinal obstruction (n=3,908). The 5-year survival rate for patients with intestinal obstruction was 37.3% (95% CI, 31.9 to 42.8), which was lower than that of patients without intestinal obstruction (45.6%; 95% CI, 43.5 to 47.7). After adjusting the hazard ratio for other prognostic variables, intestinal obstruction had a statistically significant negative correlation with the survival rate of colorectal cancer patients, with an adjusted hazard ratio of 1.22 (p=0.008).

    CONCLUSIONS: The presence of intestinal obstruction is associated with a lower survival rate among colorectal cancer patients.

    Matched MeSH terms: Survival Analysis
  19. Leong PK, Sim SM, Fung SY, Sumana K, Sitprija V, Tan NH
    PLoS Negl Trop Dis, 2012;6(6):e1672.
    PMID: 22679522 DOI: 10.1371/journal.pntd.0001672
    Snake envenomation is a serious public health threat in the rural areas of Asian and African countries. To date, the only proven treatment for snake envenomation is antivenom therapy. Cross-neutralization of heterologous venoms by antivenom raised against venoms of closely related species has been reported. The present study examined the cross neutralizing potential of a newly developed polyvalent antivenom, termed Neuro Polyvalent Snake Antivenom (NPAV). NPAV was produced by immunization against 4 Thai elapid venoms.
    Matched MeSH terms: Survival Analysis
  20. Kuze N, Sipangkui S, Malim TP, Bernard H, Ambu LN, Kohshima S
    Primates, 2008 Apr;49(2):126-34.
    PMID: 18297473 DOI: 10.1007/s10329-008-0080-7
    We analysed the reproductive parameters of free-ranging female orangutans at Sepilok Orangutan Rehabilitation Centre (SORC) on Borneo Island, Sabah, Malaysia. Fourteen adult females produced 28 offspring in total between 1967 and 2004. The average censored interbirth interval (IBI) (i.e. offspring was still alive when mother produced a next offspring) was 6 years. This was shorter than censored IBIs reported in the wild but similar to IBIs reported for those in captivity. The nonparametric survival analysis (Kaplan-Meier method) revealed a significantly shorter IBI at SORC compared with wild orangutans in Tanjung Putting. The infant (0-3 years) mortality rate at SORC of 57% was much higher than rates reported both in the wild and captivity. The birth sex-ratio was significantly biassed toward females: 24 of the 27 sex-identified infants were females. The average age at first reproduction was 11.6 years, which is younger than the age in the wild and in captivity. The high infant mortality rate might be caused by human rearing and increased transmission of disease due to frequent proximal encounters with conspecifics around the feeding platforms (FPs). This young age of first reproduction could be because of the uncertainty regarding estimated ages of the female orangutans at SORC. It may also be affected by association with other conspecifics around FPs, which increased the number of encounters of the females with males compared with the number of encounters that would take place in the wild. Provision of FPs, which improves the nutritional condition of the females, caused the shorter IBI. The female-biassed birth sex-ratio can be explained by the Trivers and Willard hypothesis. The female-biassed sex ratio could be caused by the mothers being in poor health, parasite prevalence and/or high social stress (but not food scarcity) due to the frequent encounters with conspecifics around FPs.
    Matched MeSH terms: Survival Analysis
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