Browsing by Author "Li, Shanshan"
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Item Age at Menarche and Risk of Gestational Diabetes Mellitus: A Prospective Cohort Study Among 27,482 Women(American Diabetes Association, 2016-03) Chen, Liwei; Li, Shanshan; He, Chunyan; Zhu, Yeyi; Buck Louis, Germaine M.; Yeung, Edwina; Hu, Frank B.; Zhang, Cuilin; Department of Epidemiology, Richard M. Fairbanks School of Public HealthOBJECTIVE: To examine the association between age at menarche and risk of gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS: A prospective cohort study of 42,109 eligible pregnancies from 27,482 women in the Nurses' Health Study II. RESULTS: The adjusted risk ratios for GDM across the age at menarche categories (≤11, 12, 13, and ≥14 years) were 1.34 (95% CI 1.14-1.58), 1.13 (0.97-1.31), 1.11 (0.95-1.29), and 1.00 (referent; P for trend = 0.0005), respectively. Analysis of the mediating effect indicated that 42.1% (P = 0.0007) of the association was mediated through prepregnancy BMI. CONCLUSIONS: These findings suggested that earlier menarche was significantly associated with an increased risk of GDM. This association was largely mediated through prepregnancy excessive body adiposity.Item Antihypertensive Medication and Dementia Risk in Older Adult African Americans with Hypertension: A Prospective Cohort Study(Springer, 2018-04) Murray, Michael D.; Hendrie, Hugh C.; Lane, Kathleen A.; Zheng, Mengjie; Ambuehl, Roberta; Li, Shanshan; Unverzagt, Frederick W.; Callahan, Christopher M.; Gao, Sujuan; Psychiatry, School of MedicineBACKGROUND: African Americans are especially at risk of hypertension and dementia. Antihypertensive medications reduce the risk of cardiovascular events, but may also reduce the risk of dementia. OBJECTIVE: To assess the longitudinal effects of antihypertensive medications and blood pressure on the onset of incident dementia in a cohort of African Americans. DESIGN: Prospective cohort. PARTICIPANTS: 1236 community-dwelling patients from an inner-city public health care system, aged 65 years and older, with a history of hypertension but no history of dementia, and who had at least three primary care visits and a prescription filled for any medication. MAIN MEASURES: Blood pressure was the average of three seated measurements. Dementia was diagnosed using a two-stage design, with a screening evaluation every 2 to 3 years followed by a comprehensive in-home clinical evaluation for those with a positive screen. Laboratory, inpatient and outpatient encounter data, coded diagnoses and procedures, and medication records were derived from a health information exchange. KEY RESULTS: Of the 1236 hypertensive participants without dementia at baseline, 114 (9%) developed incident dementia during follow-up. Individuals prescribed any antihypertensive medication (n = 816) were found to have a significantly reduced risk of dementia (HR = 0.57, 95% CI 0.37-0.88, p = 0.0114) compared to untreated hypertensive participants (n = 420). When this analysis was repeated including a variable indicating suboptimally treated blood pressure (> 140 mmHg systolic or >90 mmHg diastolic), the effect of antihypertensive medication was no longer statistically significant (HR = 0.65, 95% CI 0.32-1.30, p = 0.2217). CONCLUSIONS: Control of blood pressure in older adult African American patients with hypertension is a key intervention for preventing dementia, with similar benefits from most of the commonly available antihypertensive medications.Item Changes of glucose levels precede dementia in African Americans with diabetes but not in Caucasians(Elsevier, 2018-12) Hendrie, Hugh C.; Zheng, Mengjie; Lane, Kathleen A.; Ambuehl, Roberta; Purnell, Christianna; Li, Shanshan; Unverzagt, Frederick W.; Murray, Michael D.; Balasubramanyam, Ashok; Callahan, Chris M.; Gao, Sujuan; Psychiatry, School of MedicineINTRODUCTION Changes in glucose levels may represent a powerful metabolic indicator for dementia in African Americans with diabetes. It is unclear whether these changes also occur in Caucasians. METHODS A secondary data analysis using electronic medical records from 5228 African Americans and Caucasians 65 years and older. Mixed effects models with repeated serum glucose measurements were used to compare changes in glucose levels between African Americans and Caucasian patients with and without incident dementia. RESULTS African Americans and Caucasians with diabetes had significantly different changes in glucose levels by dementia status (p<0.0001). African Americans experienced a significant decline in glucose levels before the dementia diagnosis (estimated glucose decline 1.3421 mg/dL per year, p<0.0001) than those who did not develop dementia. Caucasians with and without dementia showed stable glucose levels over time (p=0.3071). DISCUSSION Significant changes in glucose levels precede dementia in African American patients with diabetes but not in Caucasians.Item Development and validation of a composite score for excessive alcohol use screening(BMJ Journals, 2016-06) Tu, Wanzhu; Chu, Chenghao; Li, Shanshan; Liangpunsakul, Suthat; Biostatistics, School of Public HealthThis study was undertaken to develop a composite measure that combines the discriminant values of individual laboratory markers routinely used for excessive alcohol use (EAU) for an improved screening performance. The training sample consisted of 272 individuals with known history of EAU and 210 non-alcoholic individuals. The validation sample included 100 EAU and 75 controls. We used the estimated regression coefficients and the observed marker values to calculate the individual's composite screening score; this score was converted to a probability measure for excessive drinking in the given individual. A threshold value for the screening score based on an examination of the estimated sensitivity and specificity associated with different threshold values was proposed. Using regression coefficients estimated from the training sample, a composite score based on the levels of aspartate aminotransferase, alanine aminotransferase, per cent carbohydrate-deficient transferrin and mean corpuscular volume was calculated. The areas under the receiver operating characteristic curve (AUC) value of the selected model was 0.87, indicating a strong discriminating power and the AUC was better than that of each individual test. The score >0.23 corresponded to a sensitivity of 90% and a specificity of nearly 60%. The AUC value remained at a respectable level of 0.83 with the sensitivity and specificity at 91% and 49%, respectively, in the validation sample. We developed a novel composite score by using a combination of commonly used biomakers. However, the development of the mechanism-based biomarkers of EAU is needed to improve the screening and diagnosis of EAU in clinical practice.Item Effect of acupuncture on lung cancer-related fatigue: study protocol for a multi-center randomized controlled trial(BioMed Central, 2019-11-09) Wang, Zhaoqin; Li, Shanshan; Wu, Luyi; Qi, Qin; Liu, Huirong; Jin, Xiaoming; Tian, Jianhui; Zhang, Ming; Ma, Xiaopeng; Sun, Deli; Xu, Shifen; Wu, Huangan; Anatomy and Cell Biology, School of MedicineBACKGROUND: Fatigue is one of the primary symptoms in lung cancer, with a prevalence of 88.0% in survivors of cancer, and an even higher prevalence post resection surgery. Effective fatigue control after lung cancer surgery is important for patient recovery and quality of life. Some studies have shown that acupuncture might be effective in treating cancer-related fatigue; however, randomized controlled trials (RCTs) of suitable sample size are limited. METHOD/DESIGN: This is a multi-center, patient-blinded RCT. A total of 320 eligible patients will be recruited in four centers and randomly assigned to either the acupuncture group or the sham acupuncture group in a 1:1 ratio. Treatment will be given twice per week for 12 sessions. Treatment will be given at acupoints GV20, GV29, CV12, CV6, CV4, and bilateral LI4, LR3, SP6, ST36. The primary outcome will be assessed using the Chinese version of The Brief Fatigue Inventory. The secondary outcomes will be measured using The European Organization for Research and The Treatment of Cancer Quality of Life Questionnaire, and the Hamilton Rating Scale for Depression. The primary outcome will be assessed at all main points (baseline, the 3rd week, the 6th week, and at follow up time points) and the secondary outcomes will be assessed at baseline and the 6th week. Intention-to-treat analysis will be used in this RCT. DISCUSSION: This trial protocol provides an example of the clinical application acupuncture treatment in the management of lung cancer-related fatigue. If the acupuncture treatment protocol confirms that acupuncture is an effective and safe option for lung cancer-related fatigue, it can be adopted as a standardized treatment. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR1900022831. Registered on 27 April 2019. URL: http://www.chictr.org.cn/showproj.aspx?proj=37823.Item Estimation of Covariate-Speci c Time-Dependent ROC Curves in the Presence of Missing Biomarkers(Wiley, 2015-09) Li, Shanshan; Ning, Yang; Department of Biostatistics, Richard M. Fairbanks School of Public HealthCovariate-specific time-dependent ROC curves are often used to evaluate the diagnostic accuracy of a biomarker with time-to-event outcomes, when certain covariates have an impact on the test accuracy. In many medical studies, measurements of biomarkers are subject to missingness due to high cost or limitation of technology. This article considers estimation of covariate-specific time-dependent ROC curves in the presence of missing biomarkers. To incorporate the covariate effect, we assume a proportional hazards model for the failure time given the biomarker and the covariates, and a semiparametric location model for the biomarker given the covariates. In the presence of missing biomarkers, we propose a simple weighted estimator for the ROC curves where the weights are inversely proportional to the selection probability. We also propose an augmented weighted estimator which utilizes information from the subjects with missing biomarkers. The augmented weighted estimator enjoys the double-robustness property in the sense that the estimator remains consistent if either the missing data process or the conditional distribution of the missing data given the observed data is correctly specified. We derive the large sample properties of the proposed estimators and evaluate their finite sample performance using numerical studies. The proposed approaches are illustrated using the US Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset.Item Is There a Correlation Between Infection Control Performance and Other Hospital Quality Measures?(Cambridge, 2017-06) O'Hara, Lyndsay M.; Morgan, Daniel J.; Pineles, Lisa; Li, Shanshan; Sulis, Carol; Bowling, Jason; Drees, Marci; Jacob, Jesse T.; Anderson, Deverick J.; Warren, David K.; Harris, Anthony D.; Biostatistics, School of Public HealthQuality measures are increasingly reported by hospitals to the Centers for Medicare and Medicaid Services (CMS), yet there may be tradeoffs in performance between infection control (IC) and other quality measures. Hospitals that performed best on IC measures did not perform well on most CMS non–IC quality measures.Item Joint modeling of bivariate time to event data with semi-competing risk(2016-09-08) Liao, Ran; Gao, Sujuan; Katz, Barry; Zhang, Ying; Li, Shanshan; Zhang, JianjunSurvival analysis often encounters the situations of correlated multiple events including the same type of event observed from siblings or multiple events experienced by the same individual. In this dissertation, we focus on the joint modeling of bivariate time to event data with the estimation of the association parameters and also in the situation of a semi-competing risk. This dissertation contains three related topics on bivariate time to event mod els. The first topic is on estimating the cross ratio which is an association parameter between bivariate survival functions. One advantage of using cross-ratio as a depen dence measure is that it has an attractive hazard ratio interpretation by comparing two groups of interest. We compare the parametric, a two-stage semiparametric and a nonparametric approaches in simulation studies to evaluate the estimation perfor mance among the three estimation approaches. The second part is on semiparametric models of univariate time to event with a semi-competing risk. The third part is on semiparametric models of bivariate time to event with semi-competing risks. A frailty-based model framework was used to accommodate potential correlations among the multiple event times. We propose two estimation approaches. The first approach is a two stage semiparametric method where cumulative baseline hazards were estimated by nonparametric methods first and used in the likelihood function. The second approach is a penalized partial likelihood approach. Simulation studies were conducted to compare the estimation accuracy between the proposed approaches. Data from an elderly cohort were used to examine factors associated with times to multiple diseases and considering death as a semi-competing risk.Item Joint modeling of recurrent event processes and intermittently observed time-varying binary covariate processes(Springer, 2016-01) Li, Shanshan; Department of Epidemiology, Richard M. Fairbanks School of Public HealthWhen conducting recurrent event data analysis, it is common to assume that the covariate processes are observed throughout the follow-up period. In most applications, however, the values of time-varying covariates are only observed periodically rather than continuously. A popular ad-hoc approach is to carry forward the last observed covariate value until it is measured again. This simple approach, however, usually leads to biased estimation. To tackle this problem, we propose to model the covariate effect on the risk of the recurrent events through jointly modeling the recurrent event process and the longitudinal measures. Despite its popularity, estimation of the joint model with binary longitudinal measurements remains a challenge, because the standard linear mixed effects model approach is not appropriate for binary measures. In this paper, we postulate a Markov model for the binary covariate process and a random-effect proportional intensity model for the recurrent event process. We use a Markov chain Monte Carlo algorithm to estimate all the unknown parameters. The performance of the proposed estimator is evaluated via simulations. The methodology is applied to an observational study designed to evaluate the effect of Group A streptococcus on pharyngitis among school children in India.Item Long-term efficacy of endoscopic cyclophotocoagulation in the management of glaucoma following cataract surgery in children(Elsevier, 2018) Cantor, Adam J.; Wang, Jingyun; Li, Shanshan; Neely, Daniel E.; Plager, David A.; Ophthalmology, School of MedicinePurpose To report the long-term efficacy of endoscopic cyclophotocoagulation (ECP) in pediatric glaucoma following cataract surgery (GFCS). Methods ECP was performed on 35 eyes of 25 patients <16 years of age with GFCS. Patients were followed for a minimum of 2 years. Treatment failure was defined as consecutive postoperative intraocular pressure (IOP) of >24 mm Hg, alternative glaucoma procedure following ECP, or occurrence of visually significant complications. Analysis was performed to estimate risk factors for failure. Results A total of 27 aphakic and 8 pseudophakic eyes were included. Pretreatment IOP averaged 33.9 ± 7.9 mm Hg. Final IOP after a mean follow-up period of 7.2 years was 18.9 ± 8.8 mm Hg (P < 0.001). The success rate was 54% (19/35 eyes). The failure rate was not increased in pseudophakic patients relative to aphakic patients. Patients with single ECP demonstrated preserved visual acuity from baseline to final follow-up. Conclusions In this patient cohort, with average follow-up period of 7.2 years, ECP was useful in the treatment of pediatric GFCS.