Mary S M Ip

The University of Hong Kong, Hong Kong, Hong Kong

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Publications (144)675.84 Total impact

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    ABSTRACT: We previously reported the involvement of serotonin (5-HT) metabolism in cigarette smoke-induced oxidative stress in rat lung in vivo. Here, we report cigarette smoke as a source of serotonin (5-HT) to the airways and aim at investigating the effects of 5-HT on oxidative stress and inflammation in human bronchial epithelial cells (BEAS-2B). A 5-HT analog was identified to be present in aqueous phase cigarette smoke using LC-MS/MS approach, which was later confirmed by a 5-HT enzyme-linked immune assay (EIA). Furthermore, exposure to 5-HT caused a time-dependent elevation of intracellular ROS level, which was blocked in the presence of apocynin (a NOX inhibitor). In support, the immunoblot analysis indicated that there was an increase in the expression of NOX2 time-dependently. 5-HT-induced elevation of IL-8 at both mRNA and protein levels was observed, which was inhibited by TEMPOL (a free radical scavenger), and inhibitors for p38 MAPK (SB203580) and ERK (U0126), in line with the time-dependent phosphorylation of p38 MAPK and ERK. In conclusion, our findings suggest that 5-HT presented in bronchial epithelium of smokers may be involved in cigarette smoke-induced oxidative stress and inflammation via activation of p38 MAPK and ERK pathway after the formation of free radicals.
    No preview · Article · Jan 2016 · Free Radical Research
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    ABSTRACT: Background: Endothelial dysfunction has been recognized to occur in the context of obstructive sleep apnea (OSA) or tobacco smoking. However, the deleterious effect on vascular function with concurrence of both conditions is largely unknown. Objective: To investigate whether the concurrence of OSA and smoking poses an additive detriment to endothelial dysfunction. Methods: Chinese men without a history of chronic medical illness were invited to complete a questionnaire including smoking pack-year exposure, polysomnography and peripheral arterial tonometry (PAT) for endothelial function. Serum 8-isoprostane, advanced oxidation protein products (AOPP) and monocyte chemo-attractant protein-1 (MCP-1) were measured. Results: 114 men were successfully enrolled. PAT ratio, adjusted for age and body mass index, correlated inversely with overall severity of OSA: apnea-hypopnea index (AHI), r = -0.160 (p = 0.092); oxygen desaturation index, r = -0.214 (p = 0.024); duration of oxygen saturation <90%, r = -0.219 (p = 0.020); and minimum oxygen saturation, r = 0.250 (p = 0.008). The PAT ratio decreased with increasing pack-year group (p = 0.018). It was lower with concurrent smoking history and moderate-severe OSA (AHI ≥15/h) compared to having one or neither factor (p = 0.011). Serum levels of 8-isoprostane and AOPP were positively related to severity of OSA, while MCP-1 correlated with smoking quantity. Multiple linear regression analyses showed that severity of intermittent hypoxia, MCP-1 and pack-year exposure were independent predictors of PAT ratio. Conclusion: While OSA, in particular intermittent hypoxemia, and tobacco smoking were independent risk factors, the concurrence of moderate-severe OSA and smoking was associated with the most severe impairment in endothelial function.
    No preview · Article · Jan 2016 · Respiration
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    Mary Y.K. Lee · Yan Wang · Judith C.W. Mak · Mary S.M. Ip
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    ABSTRACT: Aberrant release of adipocytokines from adipose tissues dysregulates cardiometabolic functions. The present study hypothesizes that chronic intermittent hypoxia (IH) present in obstructive sleep apnea leads to adipose tissue dysfunction, which in turn contributes to vascular pathogenesis. The effect of IH was evaluated in adipose depots and aortic tissues in lean rats in vivo. Further, the cellular and molecular mechanisms underlying pathophysiological interactions between adipocytes and endothelial cells were investigated in vitro. The in vivo results showed that IH induced upregulation of IL-6 and MCP-1 in subcutaneous and peri-aortic adipose tissues; and downregulated phosphorylation of endothelial nitric oxide synthase [eNOS (ser1177)] in the aorta with activation of Erk and p38 MAPK. In support, cultured adipocytes demonstrated IH-induced elevations of NADPH oxidase (NOX) 4, phosphorylation of Erk, NFκBp65 and inducible NOS (iNOS); and increased expression of IL-6 and MCP-1. Likewise, endothelial EA.hy926 (EA) cells exposed to IH showed eNOS (ser1177) and [cGMP]i reduction, while MCP-1 and iNOS expression were upregulated. Treatment of EA cells with conditioned media derived from IH-exposed cultured adipocytes caused nuclear translocation of NFκBp65 and elevation of MCP-1, which were prevented by addition of neutralizing IL-6 antibodies to the conditioned media. Recombinant IL-6 in addition to IH induced further MCP-1 release and iNOS protein expression in EA cells, which were prevented by pharmacological inhibition of Erk, p38 and NFκB. These findings suggest that IH could induce adipose tissue inflammation, which may cross-talk with endothelial cells via adipocyte-derived mediators such as IL-6, and promote NFκB-dependent endothelial dysfunction.
    Preview · Article · Jan 2016 · AJP Cell Physiology
  • Mary S M Ip · Reena Mehra · Karen S L Lam

    No preview · Article · Sep 2015 · American Journal of Respiratory and Critical Care Medicine
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    ABSTRACT: The prevalence and severity of sleep apnea (SA) in the chronic kidney disease (CKD) population is not well characterized. Recent studies have yielded highly variable prevalence rates due to cohort heterogeneity and interstudy inconsistencies in defining SA. This study sought to determine the association of SA with CKD by recruiting a uniform cohort to undertake overnight polysomnography (PSG). A total of 141 male Chinese CKD patients, ages 40-60 years, underwent overnight PSG to delineate the prevalence and severity of SA and nocturnal hypoxemia (NH). Body mass index (BMI), neck girth, estimated glomerular filtration rate, urinary protein excretion and Epworth sleepiness scale (ESS) score were collected at baseline to determine associative factors. The prevalence rates of SA and NH were 35.5 and 10.6%, respectively, in this study population [mean (±SD) age 51.44 ± 6.05 years; BMI 26.05 ± 4.22 kg/m(2)]. The adjusted odds ratios (ORs) for SA by BMI and proteinuria were 1.18 [95% confidence interval (CI) 1.02, 1.37; P ≤ 0.05] and 1.57 (95% CI 1.12, 2.46; P ≤ 0.05), respectively. The adjusted ORs for the median cohort oxygen desaturation index (ODI) by BMI and proteinuria were 1.23 (95% CI 1.05, 1.45; P ≤ 0.05) and 1.75 (95% CI 1.12, 2.76; P ≤ 0.05). However, no significant correlation between the prevalence and severity of SA and NH with progressive renal deterioration was observed. Furthermore, no significant mean difference in the apnea-hypopnea index and ODI was observed for an ESS above and below 10. SA is prevalent in CKD patients and strongly correlated with BMI and proteinuria, but not with renal function. The ESS is an investigative tool that lacks discriminatory power in patients with renal insufficiency. Therefore clinical vigilance for SA is paramount when attending to CKD patients with significant proteinuria. © The Author 2015. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.
    No preview · Article · Aug 2015 · Nephrology Dialysis Transplantation
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    ABSTRACT: Our aim was to determine the pathway underlying the effects of continuous positive airway pressure (CPAP) adherence on intimate relationship with bed partner in men with obstructive sleep apnea (OSA). We hypothesized that CPAP with good adherence affected the intimate relationship with bed partner directly and indirectly, and it was mediated through daytime sleepiness and activity level in men with OSA. Data were obtained from an education program for enhancing CPAP adherence. Men who were newly diagnosed of OSA and CPAP therapy naïve were recruited in a tertiary teaching hospital. Self-reported quality of life [Functional Outcomes of Sleep Questionnaire], daytime sleepiness [Epworth Sleepiness Scale (ESS)], and negative emotion symptoms [depression, anxiety, stress scale] were assessed before and after CPAP treatment at 1-year assessment. Seventy-three men were included in the data analysis, with a mean ± SD age of 52 ± 10 years, body mass index of 29.0 ± 5.2 kg/m(2), ESS of 9.5 ± 5.6, and median [interquartile range(IR)] apnea and hypopnea index of 31 (21, 56) events/h. The median (IR) CPAP daily usage was 4.3(0, 6.1) h/day. From the path analysis, CPAP therapy was shown to improve intimate relationship directly (ß = 0.185) and indirectly (ß = 0.050) by reducing daytime sleepiness and increasing activity level. However, negative emotion symptoms were not the mediators between CPAP adherence and the intimate relationship. CPAP therapy with good adherence is related directly and indirectly to a better intimate relationship with bed partner in men with OSA. It was possibly attributed to reduced daytime sleepiness and increased activity level.
    No preview · Article · Aug 2015 · Sleep And Breathing
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    ABSTRACT: Noninvasive detection of epidermal growth factor receptor (EGFR) mutation in plasma is feasible and could be adjunct for therapeutic monitoring especially when repeated biopsy of tumor tissue is challenging. The aims of this study were to establish the diagnostic performance of peptide nucleic acid-locked nucleic acid polymerase chain reaction followed by custom array for plasma EGFR mutation and to evaluate the association of detection with clinical characteristics and survival outcomes. Plasma genomic DNA from consecutive advanced lung cancer subjects was tested for EGFR mutations before anticancer treatment, and compared with mutation status in tumor tissue. Clinical characteristics were compared between patients who were EGFR-mutant and wild type; and within EGFR mutants, whether EGFR mutations could be detected in plasma. In 74 lung cancer patients, the sensitivity, specificity, and positive and negative predictive values of plasma EGFR detection were 79.1%, 96.8%, 97.1%, and 76.9%, respectively. EGFR mutants with concomitant detection of plasma EGFR mutation showed worse survival compared with mutants with no concomitant plasma mutation detected in biopsy specimens. Plasma EGFR mutation detected using this method demonstrated high diagnostic performance. In EGFR mutants, plasma EGFR mutation detection correlated not only EGFR mutation status in biopsy but was also associated with worse prognosis compared with EGFR mutant without plasma EGFR mutation detection. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
    Full-text · Article · Jun 2015 · Clinical Lung Cancer
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    ABSTRACT: The objective of the present study was to establish multiethnic, all-age prediction equations for estimating stature from arm span in males and females. The arm span/height ratio (ASHR) from 13 947 subjects (40.9% females), aged 5-99 years, from nine centres (in China, Europe, Ghana, India and Iran) was used to predict ASHR as a function of age using the lambda, mu and sigma method. Z-scores for forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC in 1503 patients were calculated using measured height and height calculated from arm span and age. ASHR varied nonlinearly with age, was higher in males than in females and differed significantly between the nine sites. The data clustered into four groups: Asia, Europe, Ghana and Iran. Average predicted FEV1, FVC and FEV1/FVC using measured or predicted height did not differ, with standard deviations of 4.6% for FEV1, 5.0% for FVC and 0.3% for FEV1/FVC. The percentages of disparate findings for a low FEV1, FVC and FEV1/FVC in patients, calculated using measured or predicted height, were 4.2%, 3.2% and 0.4%, respectively; for a restrictive pattern, there were 1.0% disparate findings. Group- and sex-specific equations for estimating height from arm span and age to derive predicted values for spirometry are clinically useful.
    Full-text · Article · Oct 2014 · European Respiratory Journal
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    ABSTRACT: Poor adherence to continuous positive airway pressure (CPAP) treatment in obstructive sleep apnea (OSA) adversely affects the effectiveness of this therapy. This randomized controlled trial (RCT) examined the efficacy of a brief motivational enhancement education program in improving adherence to CPAP treatment in OSA subjects. Newly diagnosed OSA subjects were recruited into this RCT. The control group received usual advice on the importance of CPAP therapy and its care. Intervention group received usual care plus brief motivational enhancement education program directed at enhancing the subjects' knowledge, motivation and self-efficacy to use CPAP through the use of a 25-minute video, a 20-minute patient-centered interview and a 10-minute telephone follow up. Self-reported daytime sleepiness adherence-related cognitions and quality of life were assessed at 1 month and 3 months. CPAP usage data was downloaded at the completion of this 3-month study. 100 OSA subjects [mean±SD: age 52±10 years, Epworth Sleepiess Scales (ESS) 9±5, median Apnea Hypopnea Index of 29 (20, 53) events/hour] prescribed CPAP treatment were recruited. The intervention group had better CPAP use [higher daily CPAP usage by 2 hours/day (Cohen d=1.33, p<0.001), a four-fold increase in the number using CPAP for ≥70% of days with ≥4 hours per day (p<0.001)], and greater improvements in daytime sleepiness (ESS) by 2.2 units (p=0.001) and treatment self-efficacy by 0.2 unit (p=0.012) compared to the control group. OSA subjects who received motivational enhancement education in addition to usual care were more likely to show better adherence to CPAP treatment, with greater improvements in treatment self-efficacy and daytime sleepiness.
    No preview · Article · May 2014 · Chest
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    ABSTRACT: Transplantation of mesenchymal stem cells (MSCs) holds great promise in the repair of cigarette smoke (CS)-induced lung damage in chronic obstructive pulmonary disease (COPD). As cigarette smoke leads to mitochondrial dysfunction, we therefore aimed to investigate the potential benefit of mitochondrial transfer from human-induced pluripotent stem cell-derived mesenchymal stem cells (iPSC-MSCs) to CS-exposed airway epithelial cells in vitro and in vivo. Rats were exposed to 4% CS for one hour daily for 56 days. At day 29 and day 43, human iPSC-MSCs or adult bone marrow-MSCs (BM-MSCs) were administered intravenously to CS-exposed rats. CS-exposed rats exhibited severe alveolar destruction with a higher mean linear intercept (Lm) than sham air-exposed rats (p < 0.001) that was attenuated in the presence of iPSC-MSCs or BM-MSCs (p < 0.01). The attenuation of Lm value and the severity of fibrosis was greater in the iPSC-MSC-treated group than the BM-MSC-treated group (p<0.05). This might be contributed to the novel observation of mitochondrial transfer from MSCs to rat airway epithelial cells in lung sections exposed to CS. In vitro studies further revealed that transfer of mitochondria from iPSC-MSCs to bronchial epithelial cells (BEAS-2B) was more effective than from BM-MSCs with preservation of adenosine triphosphate contents. This distinct mitochondrial transfer occurred via the formation of tunneling nanotubes (TNT). Inhibition of TNT formation blocked mitochondrial transfer. Our findings indicate a higher mitochondrial transfer capacity of iPSC-MSCs than BM-MSCs to rescue CS-induced mitochondrial damage. iPSC-MSCs may thus hold promise for the development of cell therapy in COPD.
    Preview · Article · Apr 2014 · American Journal of Respiratory Cell and Molecular Biology
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    ABSTRACT: Background: Surfactant proteins play a key role in alveolar stability. We examined whether single nucleotide polymorphisms (SNPs) related to the surfactant protein genes are associated with severe influenza. Methods: In the first cohort, 12 SNPs related to surfactant protein genes were compared between Chinese patients with severe and mild pandemic 2009 influenza A(H1N1) (A[H1N1]pdm09) infection who were matched for age, sex, and underlying risk conditions. The SNP rs1130866, which was significantly different between the two groups, was further genotyped in a second cohort of patients. Multivariate analysis was performed to control for confounding factors. The genotype frequencies were also compared with those of the general Han Chinese population. Results: This study consisted of 380 patients with A(H1N1)pdm09 infection. In the first cohort of 84 patients, the C allele of rs1130866, an SNP in the surfactant protein B gene (SFTPB), was significantly associated with severe disease (OR = 3.37, P = .0048), although the P value was .057 after Bonferroni correction. In the second cohort of 296 patients, the C/C genotype was confirmed in the univariate analysis to be associated with severe disease. Multivariate analysis of the second cohort showed that genotype C/C was an independent risk factor for severe A(H1N1)pdm09 infection (second cohort: OR = 2.087, P = .023). Compared to the general Han Chinese population, the C/C genotype was overrepresented in patients with severe A(H1N1)pdm09 infection (OR = 3.232, P = .00000056). Conclusions: SFTPB polymorphism is associated with severe influenza. The role of SFTPB in influenza warrants further studies.
    No preview · Article · Dec 2013 · Chest
  • Qian Han · Sze C Yeung · Mary S M Ip · Judith C W Mak
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    ABSTRACT: Obstructive sleep apnea (OSA), characterized by intermittent hypoxia (IH) during sleep, is increasingly recognized as an independent risk factor of cardiovascular diseases. OSA is associated with changes in the levels of circulating oxidative stress/inflammatory markers and dyslipidemia, supporting their mediating roles in cardiovascular pathogenesis. Our aims were to investigate the effect of IH on heart tissue using an IH-exposed rat model and to explore the potential mechanisms involved in the occurrence of cardiac damage. Male Sprague-Dawley rats were exposed to IH and intermittent normoxia as control and sacrificed after 2 or 4 weeks. IH for 4 weeks caused elevation in serum malondialdehyde and cytokine-induced neutrophil chemoattractant-1 and reduction in serum adiponectin levels. In contrast, cardiac oxidative stress and pro-inflammatory markers were suppressed while cardiac adiponectin and cholesterol levels were elevated after IH exposure for 4 weeks. In parallel, there was an increase in apoptosis in the heart of IH-exposed rats, demonstrated by elevations of Bax and cleaved caspase-3 protein and TUNEL staining. Cardiac damage was further evident with decreased arterial vessel and capillary densities, increased cardiac fibrosis, and the loss of troponin I. Our data demonstrated that IH exposure paradoxically caused systemic oxidative and inflammatory responses and cardioprotective responses, i.e., anti-oxidative and anti-inflammatory responses. Despite such a local compensatory protective mechanism, cardiac damage was observed that might be due to IH-induced cholesterol accumulation in the heart and caspase-dependent apoptosis.
    No preview · Article · Oct 2013 · Journal of physiology and biochemistry
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    ABSTRACT: The self-efficacy measure for sleep apnea (SEMSA) questionnaire was shown to be an effective tool to assess adherence-related cognitions on continuous positive airway pressure (CPAP) therapy in obstructive sleep apnea (OSA) subjects. SEMSA helps to solicit fundamental information for formulating strategies to promote CPAP adherence for better treatment outcomes. The objective of our study was to perform a linguistic and psychometric evaluation of a Chinese version of the SEMSA (SEMSA-C). Data were obtained from 100 subjects in a randomized controlled trial (RCT) on CPAP education. Subjects were newly diagnosed of OSA and naïve to CPAP therapy. A 26-item SEMSA-C was obtained by a rigorous linguistic validation process. Internal consistency was high with Cronbach α>0.88. One-week test-retest intraclass correlation coefficient (ICC) ranged from 0.70 to 0.82. Principal component factor analysis identified three of the same hypothesized factors (perceived risks, outcome expectancies, and treatment self-efficacy) as in the original version. CPAP adherence was associated with outcome expectancies and treatment self-efficacy at 3-month assessment. Further, SEMSA-C demonstrated an improvement in self-efficacy after CPAP use. SEMSA-C shows similar psychometric properties as the original English version. It is a reliable and responsive instrument to measure perceived risks, outcome expectancies, and treatment self-efficacy in Chinese subjects with OSA.
    No preview · Article · Sep 2013 · Sleep Medicine
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    ABSTRACT: Oxidative stress has been implicated in the pathogenesis of asthma. We aimed at investigating the biomarkers of oxidative stress, inflammation, and tissue damage in patients with asthma in acute exacerbation and remission. We recruited 18 asthmatics admitted to hospital with acute exacerbation and 18 healthy nonsmoking controls matched for age. We evaluated plasma levels of 8-isoprostane, C-reactive protein (CRP) and total matrix metalloproteinase- (MMP-) 9 by ELISA, and MMP-9 activity by zymographic analysis. Plasma levels of 8-isoprostane and CRP were significantly elevated in acute exacerbation and decreased in remission but remained significantly higher compared to healthy controls. The activities of pro-MMP-9 were also significantly higher in acute exacerbation and decreased in remission but remained significantly higher compared to healthy controls in parallel to plasma levels of total MMP-9. These data suggest that overproduction of MMP-9 along with highly elevated levels of oxidative stress and inflammation is implicated in asthma exacerbation and that measurements of these biomarkers can be a valid index in its management.
    Preview · Article · Aug 2013
  • Qian Han · Sze Chun Yeung · Mary Sau Man Ip · Judith Choi Wo Mak
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    ABSTRACT: Intermittent hypoxia (IH) is a hallmark feature in obstructive sleep apnea (OSA) which is increasingly recognized as an independent risk factor for atherosclerosis. Oxidative stress, inflammation, and cell apoptosis are major pathological events initiating or accelerating atherogenesis. This study addressed whether IH would affect these proatherogenic factors in endothelial cells and the mechanistic pathways involved. EA.hy926 cells were exposed to intermittent normoxia or IH for different numbers of cycles (32, 64, or 96). IH exposure time-dependently raised cellular GSSG/GSH ratio, increased production of IL-6 and IL-8, and accelerated cell apoptosis and death, concurrent with activation of NF-κB and inhibition of Nrf2/HO-1 pathways. At 64 cycles, inhibition of NF-κB attenuated IH-induced cellular oxidative stress and accumulation of inflammatory cytokines in cell culture medium but aggravated IH-induced cell apoptosis, while stimulation of HO-1 suppressed IH-induced cellular oxidative stress and cell apoptosis without affecting accumulation of inflammatory cytokines in cell culture medium. We demonstrated that early stage of exposure to IH-induced oxidative and inflammatory stresses leading to acceleration of cell apoptosis via NF-κB and Nrf2/HO-1 pathways in endothelial cells, suggesting the potential mechanisms for IH-induced vascular pathogenesis, in resemblance to OSA.
    No preview · Article · Dec 2012 · Cell biochemistry and biophysics
  • Y. M. Liang · S. C. Yeung · M. S. M. Ip · J. C. W. Mak

    No preview · Article · Dec 2012 · Respirology
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    ABSTRACT: Our recent study has indicated that Chinese green tea (Lung Chen), in which epigallocatechin-3-gallate (EGCG) accounts for 60% of catechins, protected cigarette smoke-induced lung injury. We now hypothesized that Lung Chen tea may also have potential effect on lung oxidative stress and proteases/anti-proteases in a smoking rat model. Sprague-Dawley rats were exposed to either sham air (SA) or 4% cigarette smoke (CS) plus 2% Lung Chen tea or water by oral gavage. Serine proteases, matrix metalloproteinases (MMPs) and their respective endogenous inhibitors were determined in bronchoalveolar lavage (BAL) and lung tissues by gelatin/casein zymography and biochemical assays. Green tea consumption significantly decreased CS-induced elevation of lung lipid peroxidation marker, malondialdehyde (MDA), and CS-induced up-regulation of neutrophil elastase (NE) concentration and activity along with that of α(1)-antitrypsin (α(1)-AT) and secretory leukoproteinase inhibitor (SLPI) in BAL and lung. In parallel, significant elevation of MMP-12 activity was found in BAL and lung of the CS-exposed group, which returned to the levels of SA-exposed group after green tea consumption but not CS-induced reduction of tissue inhibitor of metalloproteinase (TIMP)-1 activity, which was not reversed by green tea consumption. Taken together, our data supported the presence of local oxidative stress and protease/anti-protease imbalance in the airways after CS exposure, which might be alleviated by green tea consumption through its biological antioxidant activity.
    No preview · Article · May 2012 · Free Radical Research

  • No preview · Conference Paper · May 2012
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    ABSTRACT: Forced expiratory volume in 3 seconds (FEV(3)) and 6 seconds (FEV(6)) could complement FEV(1) and forced vital capacity (FVC) for detecting airflow obstruction. To compare FEV(1)/ FEV(6) and FEV(3)/FVC with FEV(1)/FVC in the detection of airflow obstruction. Previous lung function data were re-analysed to establish reference values for FEV(3) and FEV(6). Data from a separate cohort of male smokers were used as test set. FEV(1), FEV(3), FEV(6), FVC, FEV(1)/FVC, FEV(1)/ FEV(6) and FEV(3)/FVC were regressed against age, standing height, weight and body mass index, and the mean and 95% confidence intervals for the lower limit of normal (LLN) values for these parameters were determined. The percentage of smokers with airflow obstruction in the test population using FEV(1)/FVC < LLN was 15.0%, while using FEV(1)/ FEV(6) < LLN and FEV(3)/FVC < LLN they were respectively 18.5% and 18.1%. Using FEV(1)/FVC < LLN as reference, the sensitivity and specificity of FEV(1)/ FEV(6) < LLN in identifying airflow obstruction were 82.3% and 92.8%, while those for FEV(3)/FVC < LLN were 78.5% and 92.6%; the positive and negative predictive values were 67% and 96.7% for FEV(1)/ FEV(6) < LLN and 65.3% and 96% for FEV(3)/FVC < LLN. FEV(3)/FVC < LLN and FEV(1)/ FEV(6) < LLN are comparable to FEV(1)/FVC < LLN for detecting airflow obstruction. FEV(3)/FVC < LLN could be useful in screening for airflow obstruction, while FEV(1)/ FEV(6) < LLN is useful in detecting airflow limitation in the elderly or in subjects with severe airflow obstruction.
    No preview · Article · May 2012 · The International Journal of Tuberculosis and Lung Disease

  • No preview · Conference Paper · May 2012

Publication Stats

5k Citations
675.84 Total Impact Points


  • 1993-2015
    • The University of Hong Kong
      • Department of Medicine
      Hong Kong, Hong Kong
  • 1989-2015
    • Queen Mary Hospital
      Hong Kong, Hong Kong
  • 2008
    • University of Chicago
      • Department of Medicine
      Chicago, IL, United States
  • 2005
    • Vancouver General Hospital
      Vancouver, British Columbia, Canada
  • 1991
    • UHN: Toronto General Hospital
      Toronto, Ontario, Canada
  • 1986
    • The University of Edinburgh
      Edinburgh, Scotland, United Kingdom