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Dr. Tiffany  Chan  Dds image

Dr. Tiffany Chan Dds

100 W El Camino Real Ste 63A
Mountain View CA 94040
650 642-2626
Medical School: Other - Unknown
Accepts Medicare: No
Participates In eRX: No
Participates In PQRS: No
Participates In EHR: No
License #: 61792
NPI: 1558601583
Taxonomy Codes:
122300000X

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Publications

Equating Visual Function Scales to Facilitate Reporting of Medicare Functional G-Code Severity/Complexity Modifiers for Low Vision Patients. - Archives of physical medicine and rehabilitation
To present a method of estimating and equating scales across functional assessment instruments that appropriately represent changes in a patient's functional ability and can be meaningfully mapped to changes in Medicare G-code severity modifiers.Previously published measures of patients' overall visual ability, estimated from low vision patient responses to seven different visual function rating scale questionnaires, are equated and mapped onto Medicare G-code severity modifiers SETTING: Outpatient low vision rehabilitation clinics.The analyses presented in this paper were performed on raw or summarized low vision patient ratings of visual function questionnaire (VFQ) items obtained from previously published research studies.Previously published visual ability measures from Rasch analysis of low vision patent ratings of items in different visual function questionnaires (NEI VFQ, VF-14, ADVS, and VAQ) were equated with the Activity Inventory (AI) scale - the 39 items in the SRAFVP and the 48 items in the VA LV VFQ were paired with similar items in the AI in order to equate the scales.Tests using different observation methods and indicators cannot be directly compared on the same scale. All test results would have to be transformed to measures of the same functional ability variable on a common scale as described here, before a single measure could be estimated from the multiple measures.Bivariate regression analysis was performed to linearly transform the SRAFVP and VA LV VFQ item measures to the AI item measure scale. The nonlinear relationship between person measures of visual ability on a logit scale and item response raw scores was approximated with a logistic function, and the two regression coefficients were estimated for each of the seven VFQs. These coefficients can be used with the logistic function to estimate functional ability on the same interval scale for each VFQ and for transforming raw VFQ responses to Medicare's G-code severity modifier categories.The principle of using equated interval scales allows for comparison across measurement instruments of low vision functional status and outcomes, but can be applied to any area of rehabilitation.Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.
Breast cancer screening controversies: who, when, why, and how? - Clinical imaging
Mammographic screening is effective in reducing mortality from breast cancer. The issue is not whether mammography is effective, but whether the false positive rate and false negative rates can be reduced. This review will discuss controversies including the reduction in breast cancer mortality, overdiagnosis, the ideal screening candidate, and the optimal imaging modality for breast cancer screening. The article will compare and contrast screening mammography, tomosynthesis, whole-breast screening ultrasound, magnetic resonance imaging, and molecular breast imaging. Though supplemental imaging modalities are being utilized to improve breast cancer diagnosis, mammography still remains the gold standard for breast cancer screening.Copyright © 2015. Published by Elsevier Inc.
Molecular subgroups of atypical teratoid rhabdoid tumours in children: an integrated genomic and clinicopathological analysis. - The Lancet. Oncology
Rhabdoid brain tumours, also called atypical teratoid rhabdoid tumours, are lethal childhood cancers with characteristic genetic alterations of SMARCB1/hSNF5. Lack of biological understanding of the substantial clinical heterogeneity of these tumours restricts therapeutic advances. We integrated genomic and clinicopathological analyses of a cohort of patients with atypical teratoid rhabdoid tumours to find out the molecular basis for clinical heterogeneity in these tumours.We obtained 259 rhabdoid tumours from 37 international institutions and assessed transcriptional profiles in 43 primary tumours and copy number profiles in 38 primary tumours to discover molecular subgroups of atypical teratoid rhabdoid tumours. We used gene and pathway enrichment analyses to discover group-specific molecular markers and did immunohistochemical analyses on 125 primary tumours to evaluate clinicopathological significance of molecular subgroup and ASCL1-NOTCH signalling.Transcriptional analyses identified two atypical teratoid rhabdoid tumour subgroups with differential enrichment of genetic pathways, and distinct clinicopathological and survival features. Expression of ASCL1, a regulator of NOTCH signalling, correlated with supratentorial location (p=0·004) and superior 5-year overall survival (35%, 95% CI 13-57, and 20%, 6-34, for ASCL1-positive and ASCL1-negative tumours, respectively; p=0·033) in 70 patients who received multimodal treatment. ASCL1 expression also correlated with superior 5-year overall survival (34%, 7-61, and 9%, 0-21, for ASCL1-positive and ASCL1-negative tumours, respectively; p=0·001) in 39 patients who received only chemotherapy without radiation. Cox hazard ratios for overall survival in patients with differential ASCL1 enrichment treated with chemotherapy with or without radiation were 2·02 (95% CI 1·04-3·85; p=0·038) and 3·98 (1·71-9·26; p=0·001). Integrated analyses of molecular subgroupings with clinical prognostic factors showed three distinct clinical risk groups of tumours with different therapeutic outcomes.An integration of clinical risk factors and tumour molecular groups can be used to identify patients who are likely to have improved long-term radiation-free survival and might help therapeutic stratification of patients with atypical teratoid rhabdoid tumours.C17 Research Network, Genome Canada, b.r.a.i.n.child, Mitchell Duckman, Tal Doron and Suri Boon foundations.Copyright © 2015 Elsevier Ltd. All rights reserved.
The structure of SAV1646 from Staphylococcus aureus belonging to a new `ribosome-associated' subfamily of bacterial proteins. - Acta crystallographica. Section D, Biological crystallography
The crystal structure of the SAV1646 protein from the pathogenic microorganism Staphylococcus aureus has been determined at 1.7 Å resolution. The 106-amino-acid protein forms a two-layer sandwich with α/β topology. The protein molecules associate as dimers in the crystal and in solution, with the monomers related by a pseudo-twofold rotation axis. A sequence-homology search identified the protein as a member of a new subfamily of yet uncharacterized bacterial `ribosome-associated' proteins with at least 13 members to date. A detailed analysis of the crystal protein structure along with the genomic structure of the operon containing the sav1646 gene allowed a tentative functional model of this protein to be proposed. The SAV1646 dimer is assumed to form a complex with ribosomal proteins L21 and L27 which could help to complete the assembly of the large subunit of the ribosome.
Review of a medical student-run surgery lecture series and skills lab curriculum. - Canadian journal of surgery. Journal canadien de chirurgie
Evidence suggests that early exposure to surgical techniques, surgical knowledge and mentors strongly correlates with students’ interest, knowledge and confidence in general surgery as a postgraduate career choice. Preclerkship exposure to surgery and implementation of a formal surgical curriculum is often restricted owing to attending surgeon time commitments and cost limitations. To promote earlier exposure to surgery, a group of senior medical students at McMaster University, Hamilton, Ont., developed and implemented a novel pilot program with a surgical lecture series and a surgical skills laboratory for preclerkship students. This commentary discusses the effectiveness of these initiatives.
Breast abscess: evidence based management recommendations. - Expert review of anti-infective therapy
Literature review was carried out and studies reporting on treatment of breast abscesses were critically appraised for quality and their level of evidence using the Strength of Recommendation Taxonomy guidelines, and key recommendations were summarized. Needle aspiration either with or without ultrasound guidance should be employed as first line treatment of breast abscesses. This approach has the potential benefits of: superior cosmesis, shorter healing time, and avoidance of general anaesthesia. Multiple aspiration sessions may be required for cure. Ultrasound-guided percutaneous catheter placement may be considered as an alternative approach for treatment of larger abscesses (>3 cm). Surgical incision and drainage should be considered for first line therapy in large (>5 cm), multiloculated, or long standing abscesses, or if percutaneous drainage is unsuccessful. All patients should be treated concurrently with antibiotics. Patients with recurrent subareolar abscesses and fistulas should be referred for consideration of surgical treatment.
Characterizing functional complaints in patients seeking outpatient low-vision services in the United States. - Ophthalmology
To characterize functional complaints of new low-vision rehabilitation patients.Prospective observational study.The Low Vision Rehabilitation Outcomes Study recruited 819 patients between 2008 and 2011 from 28 clinical centers in the United States.New patients referred for low-vision rehabilitation were asked, "What are your chief complaints about your vision?" before their appointment. Full patient statements were transcribed as free text. Two methods assessed whether statements indicated difficulty in each of 13 functional categories: (1) assessment by 2 masked clinicians reading the statement, and (2) a computerized search of the text for specific words or word fragments. Logistic regression models were used to predict the influence of age, gender, and visual acuity on the likelihood of reporting a complaint in each functional category.Prevalence and risk factors for patient concerns within various functional categories.Reading was the most common functional complaint (66.4% of patients). Other functional difficulties expressed by at least 10% of patients included driving (27.8%), using visual assistive equipment (17.5%), mobility (16.3%), performing in-home activities (15.1%), lighting and glare (11.7%), and facial recognition and social interactions (10.3%). Good agreement was noted between the masked clinician graders and the computerized algorithm for categorization of functional complaints (median κ of 0.84 across the 13 categories). Multivariate logistic regression models demonstrated that the likelihood of reading difficulties increased mildly with age (odds ratio, 1.4 per 10-year increment in age; 95% confidence interval, 1.3-1.6), but did not differ with visual acuity (P = 0.09). Additionally, men were more likely to report driving difficulties and difficulties related to lighting, whereas women were more likely to report difficulty with either in-home activities or facial recognition or social interaction (P<0.05 for all). Mobility concerns, defined as walking difficulty and out-of-home activities, showed no relationship to gender, age, or visual acuity.Reading was the most commonly reported difficulty, regardless of the patient's diagnosis. Neither visual acuity nor gender were predictive of reading concerns, although, age showed a small effect. Addressing reading rehabilitation should be a cornerstone of low-vision therapy.Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.
A NSQIP risk assessment for thyroid surgery based on comorbidities. - Journal of the American College of Surgeons
Thyroid surgery is associated with low mortality and morbidity and often is performed in an ambulatory setting. The majority of patients undergoing thyroidectomy have an uncomplicated outcome, but common comorbidities may increase mortality and morbidity. Due to low complication rates, studies using single surgeon or single institutional data to identify risk factors for adverse outcomes may be limited by inadequate patient volume.This retrospective cohort study used data from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP). The study group included all thyroidectomy patients over a 6-year period (2005 to 2010). Common patient comorbidities were identified and analyzed using logistic regression. Risk of adverse outcomes was calculated for single and multiple comorbidities. Statistical significance was set at p < 0.05.The study group included 38,577 consecutive patients. Thirty-day mortality and postoperative morbidity were 0.06% and 1.49%, respectively. The risk factors independently associated with morbidity included hypertension, diabetes, advanced age greater than 70 years, COPD, dialysis, malignant thyroid disease, and surgical approach (total thyroidectomy). Substernal thyroidectomy, hypertension, diabetes, age greater than 70 years, COPD, and dialysis were significant predictors (unadjusted) of mortality. Multiple comorbidities resulted in significant cumulative risk. The presence of 3 or more comorbidities was associated with a postoperative morbidity of 5.1% (p < 0.001) and mortality as high as 12.5%.Thyroid surgery is generally safe. Common comorbidities significantly increase the risk of adverse outcomes and death. Clinically applicable risk calculation based on overall health may improve patient selection, surgical management, and informed consent.Copyright © 2014 American College of Surgeons. Published by Elsevier Inc. All rights reserved.
A survey of the current status of coronary CT angiography using 64-slice multidetector CT in Taiwan. - Journal of the Formosan Medical Association = Taiwan yi zhi
The 64-slice multidetector CT (64-MDCT) has bolstered the sensitivity and specificity of coronary CT angiography (CCTA) for detecting coronary artery disease. We performed this study to understand the current status of CCTA using 64-MDCT, so as to determine further promotion and optimal regulation schemes of CCTA in Taiwan.Information about CCTA from 68 domestic hospitals with 64-MDCT was collected by means of a questionnaire from July 2009 to January 2010. The studied details included: (1) the implementation background of CCTA; (2) the interdisciplinary cooperation and report processing of CCTA; and (3) the promotion strategy of CCTA.The majority of CCTA sites (89.7%) were administered by diagnostic radiologists. Most cardiologists and cardiac surgeons have confirmed its clinical value by referring patients to undergo CCTA. Of the CCTA reports by radiologists, 41.2% had their report supplemented by referring cardiologists. Such cooperation amongst specialists promoted the development of CCTA. Of CCTA studies, 89.7% included coronary calcium scoring. Most (60.3%) respondents asserted the cost of a study to be 15,000 to 20,000 new Taiwan dollars. Nearly two-fifths (41.2%) of the respondents supported the restriction of subjects for CCTA to those who were high risk group for coronary artery disease or those > 40 years of age.Diagnostic radiologists are primarily in charge of managing CCTA sites in Taiwan. The interdisciplinary cooperation amongst radiologists and cardiologists in reporting CCTA may expedite the development of CCTA. The domestic radiologists are expected to standardize the process, which includes interpreting and reporting CCTA findings.Copyright © 2012. Published by Elsevier B.V.
The human microbiota: a new direction in the investigation of thoracic diseases. - Journal of thoracic disease
Advancements in next generation sequencing technology have provided means for the comprehensive profiling of the microbial community in the respiratory tract in both physiological and pathological conditions. Recent studies have analyzed the bacterial composition in the respiratory tract of chronic obstructive pulmonary disease (COPD), influenza and tuberculosis patients, and have identified novel targets that may potentially lead to secondary infections. Certain bacteria have also been found to regulate the lung immune system and have unexpected connections with respiratory diseases. Further studies in these areas are necessary to dissect the exact relationship between the dynamics of the microbiota and the health of the respiratory system.

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