Biomedical subjects

Stanley Xu

Publications and source records attributed to Stanley Xu.

13 recordsLinked to original sources

PubMed2006

Safety of trivalent inactivated influenza vaccine in children 6 to 23 months old.

CONTEXT: Beginning with the winter season of 2004-2005, influenza vaccination has been recommended for all children 6 to 23 months old in the United States. However, its safety in young children has not been adequately studied in large populations. OBJECTIVE: To screen for medically attended events in the clinic, emergency department, or hospital after administration of trivalent inactivated influenza vaccine in children 6 to 23 months old. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort using self-control analysis, with chart review of significant medically attended events at 8 managed care organizations in the United States that comprise the Vaccine Safety Datalink. Participants were all children in the Vaccine Safety Datalink cohort 6 to 23 months old who received trivalent inactivated influenza vaccine between January 1, 1991, and May 31, 2003 (45,356 children with 69,359 vaccinations). MAIN OUTCOME MEASURE: Any medically attended event significantly associated with trivalent inactivated influenza vaccine in risk windows 0 to 3 days, 1 to 14 days (primary analysis), 1 to 42 days, or 15 to 42 days after vaccination, compared with 2 control periods, one before vaccination and the second after the risk window. All individual ICD-9 codes as well as predefined aggregate codes were examined. RESULTS: Before chart review, only 1 diagnosis, gastritis/duodenitis, was more likely to occur in the 14 days after trivalent inactivated influenza vaccine (matched odds ratio [OR], 5.50; 95% confidence interval [CI], 1.22-24.81 for control period 1, and matched OR, 4.33; 95% CI, 1.23-15.21 for control period 2). Thirteen medically attended events were less likely to occur after trivalent inactivated influenza vaccine, including acute upper respiratory tract infection, asthma, bronchiolitis, and otitis media. After chart review, gastritis/duodenitis was not significantly associated with trivalent inactivated influenza vaccine (matched OR, 4.00; 95% CI, 0.85-18.84 for control period 1; matched OR, 3.34; 95% CI, 0.92-12.11 for control period 2). CONCLUSIONS: In the largest population-based study to date of the safety of trivalent inactivated influenza vaccine in young children, there were very few medically attended events, none of which were serious, significantly associated with the vaccine. This study provides additional evidence supporting the safety of universally immunizing all children 6 to 23 months old with influenza vaccine.

Cohort Studies↗

PubMed2006

Telephone screening for hazardous drinking among injured patients seen in acute care clinics: feasibility study.

AIMS: We evaluated the effectiveness of telephoning injured patients after discharge, compared with contacting them in the clinic during the acute care visit, for screening for hazardous drinking and eliciting willingness to participate in a lifestyle intervention trial. METHODS: We conducted a quasi-randomized controlled trial among acutely injured adult patients in trauma and acute care clinics, assigning telephone and clinic screening strategies systematically by week. During telephone weeks, we mailed study information to patients identified from computerized records, then telephoned them. During clinic weeks, researchers recruited patients awaiting care. We screened for hazardous drinking using the AUDIT-C (Alcohol Use Disorders Identification Test-C). We examined the proportion of all injured adult patients who were screened, the proportion of screened patients with hazardous drinking (AUDIT-C score >or=4), and the proportion willing to participate in a (hypothetical) lifestyle intervention trial. Differences were analysed with non-linear mixed models using generalized estimating equations, controlling for age, sex, and facility. Levers and barriers to screening were explored through structured interviews with research staff. RESULTS: We enrolled 29% (469/1,609) of all injured adult patients and 76% of injured patients contacted and found to be eligible. Of screened patients, 23.1% screened positive for hazardous drinking. Telephone and clinic contact were equally effective for screening patients (OR = 1.05; 95% CI = 0.59-1.87), identifying hazardous drinking (OR=0.97; 95% CI = 0.54-1.74), and eliciting willingness to participate in an intervention trial (OR=1.49; 95% CI = 0.97-2.30). Clinic site modified results: telephone was more effective than clinic contact for screening urban patients (OR=1.99; 95% CI = 1.36-2.93), but less effective for screening suburban patients (OR = 0.70; 95% CI = 0.69-0.71). Barriers to clinic screening included lack of clinic staff support, time constraints, and difficulty recruiting elderly or acutely distressed patients. Barriers to telephone screening included erroneous contact information and failure to answer the telephone. CONCLUSIONS: Telephone screening is a feasible and efficient method for screening moderately injured adult patients for hazardous drinking, but characteristics of the clinical site (including personnel) influence its effectiveness. Trauma and acute care clinics are likely to be fruitful sites for identification of patients with hazardous drinking, whether for enrollment into brief intervention trials or treatment programmes.

Adult↗

PubMed2006

Four different study designs to evaluate vaccine safety were equally validated with contrasting limitations.

OBJECTIVE: We conducted a simulation study to empirically compare four study designs [cohort, case-control, risk-interval, self-controlled case series (SCCS)] used to assess vaccine safety. STUDY DESIGN AND METHODS: Using Vaccine Safety Datalink data (a Centers for Disease Control and Prevention-funded project), we simulated 250 case sets of an acute illness within a cohort of vaccinated and unvaccinated children. We constructed the other three study designs from the cohort at three different incident rate ratios (IRRs, 2.00, 3.00, and 4.00), 15 levels of decreasing disease incidence, and two confounding levels (20%, 40%) for both fixed and seasonal confounding. Each of the design-specific study samples was analyzed with a regression model. The design-specific beta; estimates were compared. RESULTS: The beta; estimates of the case-control, risk-interval, and SCCS designs were within 5% of the true risk parameters or cohort estimates. However, the case-control's estimates were less precise, less powerful, and biased by fixed confounding. The estimates of SCCS and risk-interval designs were biased by unadjusted seasonal confounding. CONCLUSIONS: All the methods were valid designs, with contrasting strengths and weaknesses. In particular, the SCCS method proved to be an efficient and valid alternative to the cohort method.

Acute Disease↗

PubMed2006

Impact of maternal influenza vaccination during pregnancy on the incidence of acute respiratory illness visits among infants.

OBJECTIVE: To determine whether influenza vaccination of pregnant women prevents visits for respiratory illness in their infants born during the influenza season. DESIGN: Retrospective matched cohort study. SETTING: Four managed care organizations in the United States. Patients A total of 41 129 infants (3160 and 37 969 born to vaccinated and unvaccinated mothers, respectively) born between 1995 and 2001. Main Exposure Maternal influenza vaccination. Infants were considered exposed if their gestational age at birth was at least 30 weeks, if the time from maternal vaccination to birth was at least 28 days, and if they were exposed to at least 14 days of the influenza season. MAIN OUTCOME MEASURES: Incidence of acute respiratory illnesses (outpatient, emergency department, and inpatient settings combined) and incident rate ratios (IRRs) for infants exposed and unexposed to maternal vaccination during the following 4 periods: peak influenza, respiratory syncytial virus predominant, periseasonal, and summer weeks. The time to the first acute respiratory illness during peak influenza weeks was also assessed. RESULTS: During the peak influenza weeks, infant visit rates were 15.4 and 17.1 per 100 person-months for exposed and unexposed infants, respectively (IRR, 0.90; 95% confidence interval, 0.80-1.02). Adjusted IRRs for the 4 periods found a protective effect of infant female sex, whereas Medicaid status and maternal high-risk status increased infant visit rates. Maternal influenza vaccination did not reduce visit rates during any of the 4 time periods (IRR for peak influenza season, 0.96; 95% confidence interval, 0.86-1.07) and did not delay the onset of first respiratory illness. CONCLUSION: We were unable to demonstrate that maternal influenza vaccination reduces respiratory illness visit rates among their infants.

Adult↗

PubMed2006

Continuous time Markov models for binary longitudinal data.

Longitudinal data usually consist of a number of short time series. A group of subjects or groups of subjects are followed over time and observations are often taken at unequally spaced time points, and may be at different times for different subjects. When the errors and random effects are Gaussian, the likelihood of these unbalanced linear mixed models can be directly calculated, and nonlinear optimization used to obtain maximum likelihood estimates of the fixed regression coefficients and parameters in the variance components. For binary longitudinal data, a two state, non-homogeneous continuous time Markov process approach is used to model serial correlation within subjects. Formulating the model as a continuous time Markov process allows the observations to be equally or unequally spaced. Fixed and time varying covariates can be included in the model, and the continuous time model allows the estimation of the odds ratio for an exposure variable based on the steady state distribution. Exact likelihoods can be calculated. The initial probability distribution on the first observation on each subject is estimated using logistic regression that can involve covariates, and this estimation is embedded in the overall estimation. These models are applied to an intervention study designed to reduce children's sun exposure.

Biometry↗

PubMed2006

Differential effectiveness of depression disease management for rural and urban primary care patients.

CONTEXT: Federally qualified health centers across the country are adopting depression disease management programs following federally mandated training; however, little is known about the relative effectiveness of depression disease management in rural versus urban patient populations. PURPOSE: To explore whether a depression disease management program has a comparable impact on clinical outcomes over 2 years in patients treated in rural and urban primary care practices and whether the impact is mediated by receiving evidence-based care (antidepressant medication and specialty care counseling). METHODS: A preplanned secondary analysis was conducted in a consecutively sampled cohort of 479 depressed primary care patients recruited from 12 practices in 10 states across the country participating in the Quality Enhancement for Strategic Teaming study. FINDINGS: Depression disease management improved the mental health status of urban patients over 18 months but not rural patients. Effects were not mediated by antidepressant medication or specialty care counseling in urban or rural patients. CONCLUSIONS: Depression disease management appears to improve clinical outcomes in urban but not rural patients. Because these programs compete for scarce resources, health care organizations interested in delivering depression disease management to rural populations need to advocate for programs whose clinical effectiveness has been demonstrated for rural residents.

Adult↗

PubMed2005

Impact of the introduction of pneumococcal conjugate vaccine on immunization coverage among infants.

BACKGROUND: The introduction of pneumococcal conjugate vaccine (PCV) to the U.S. recommended childhood immunization schedule in the year 2000 added three injections to the number of vaccinations a child is expected to receive during the first year of life. Surveys have suggested that the addition of PCV has led some immunization providers to move other routine childhood vaccinations to later ages, which could increase the possibility of missing these vaccines. The purpose of this study was to evaluate whether introduction of PCV affected immunization coverage for recommended childhood vaccinations among 13-month olds in four large provider groups. METHODS: In this retrospective cohort study, we analyzed computerized data on vaccinations for 33,319 children in four large provider groups before and after the introduction of PCV. The primary outcome was whether the child was up to date for all non-PCV recommended vaccinations at 13 months of age. Logistic regression was used to evaluate the association between PCV introduction and the primary outcome. The secondary outcome was the number of days spent underimmunized by 13 months. The association between PCV introduction and the secondary outcome was evaluated using a two-part modelling approach using logistic and negative binomial regression. RESULTS: Overall, 93% of children were up-to-date at 13 months, and 70% received all non-PCV vaccinations without any delay. Among the entire study population, immunization coverage was maintained or slightly increased from the pre-PCV to post-PCV periods. After multivariate adjustment, children born after PCV entered routine use were less likely to be up-to-date at 13 months in one provider group (Group C: OR = 0.5; 95% CI: 0.3-0.8) and were less likely to have received all vaccine doses without any delay in two Groups (Group B: OR = 0.4, 95% CI: 0.3 - 0.6; Group C: OR = 0.5, 95% CI: 0.4-0.7). This represented 3% fewer children in Group C who were up-to-date and 14% (Group C) to 16% (Group B) fewer children who spent no time underimmunized at 13 months after PCV entered routine use compared to the pre-PCV baseline. Some disruptions in immunization delivery were also observed concurrent with temporary recommendations to suspend the birth dose of hepatitis B vaccine, preceding the introduction of PCV. CONCLUSION: These findings suggest that the introduction of PCV did not harm overall immunization coverage rates in populations with good access to primary care. However, we did observe some disruptions in the timely delivery of other vaccines coincident with the introduction of PCV and the suspension of the birth dose of hepatitis B vaccine. This study highlights the need for continued vigilance in coming years as the U.S. introduces new childhood vaccines and policies that may change the timing of existing vaccines.

Cohort Studies↗

PubMed2005

Effect of CME on primary care and OB/GYN treatment of breast masses.

INTRODUCTION: CME program planners are being asked to move beyond assessments of knowledge to assessing the impact of CME on practice and patient outcomes. METHODS: We conducted a pre-post analysis of administrative data from 107 physicians, nurse practitioners (NPs), or physician's assistants (PAs) who attended one or two continuing medical education (CME) programs (an in-person, mainly didactic session on breast complaints in women, or an individual mentorship with general surgeons) between August 2002 and March 2003. We examined associations between the number of trainings and attempted breast mass aspirations or general surgery referrals for breast masses; individual training and breast mass aspiration attempts or general surgery referrals; and provider type and attempted breast mass aspirations. Generalized linear mixed models were used to model dichotomous outcomes. RESULTS: Clinicians who participated in individual trainings performed more breast mass aspirations after training (odds ratio (OR) 3.07, [95% confidence interval 1.10-8.54]). Participants who completed two trainings performed more breast mass aspirations after training (OR 2.33, [1.19-4.57]), while those who completed just one did not (OR 1.34, [0.39, 4.58]) but the effect started after the first training and did not strengthen after the second training. NPs and PAs attempted more aspirations after training (OR 6.1, [1.54, 24.1]), whereas physicians did not (OR 0.89 [0.36, 2.22]). Training was not associated with a change in referrals to general surgery. Referral appropriateness, pre-training readiness to change, and previous training in breast mass aspiration were not assessed. DISCUSSION: Attempts to aspirate breast masses may increase after CME training. Individual training may be more effective than group training in increasing the likelihood of attempted aspirations.

Breast Diseases↗

PubMed2004

Health services use and health care costs of obese and nonobese individuals.

BACKGROUND: Obesity has clinical and economic consequences. Few studies have compared health care resource utilization between age- and sex-matched obese and nonobese persons. METHODS: We conducted a retrospective study in obese and nonobese individuals matched by age, sex, medical clinic, and selected exclusionary diagnoses. Data collected included hospitalizations, outpatient visits, professional claims, and prescriptions over 1 year. Costs were assigned to medical resources based on market prices using publicly available costs. Comorbid conditions were determined using a chronic disease score (CDS) index. Groups were compared on types and costs of resources consumed. Regression models were used to examine the effect of body mass index (BMI) on costs while controlling for age and chronic diseases. RESULTS: A total of 539 obese and 1225 nonobese persons were examined. Obese patients had more hospitalizations (P<.001), prescription drugs (P<.001), professional claims (P<.001), and outpatient visits (P = .005). Obese patients used more cardiovascular, intranasal allergic rhinitis, asthma, ulcer, diabetes, thyroid, and analgesic drugs. Total costs between groups were different (median of $585.44 for obese and $333.24 for nonobese patients; P<.001). Cost differences were primarily due to medications (P<.001). Predictors of total costs were age, sex, BMI, and CDS. For each unit BMI increase, costs increased 2.3% (P<.001). For each CDS unit increase, costs increased 52.9% (P<.001). CONCLUSION: Over 1 year, health care costs for obese persons are higher than for nonobese persons, primarily because of prescription drugs.

Adult↗

PubMed2004

Safety of the trivalent inactivated influenza vaccine among children: a population-based study.

BACKGROUND: To our knowledge, there are no published population-based studies on the safety of the inactivated trivalent influenza vaccine among children. OBJECTIVE: To screen a large population of children for evidence of increased medical visits in the 2 weeks after influenza vaccination compared with 2 control periods. Secondary analyses included shorter risk periods and restricted age categories. DESIGN: Self-control screening analysis. Children vaccinated from January 1, 1993, through December 31, 1999, were randomly divided into 2 equal groups. In group 1, risks of outpatient, emergency department, and inpatient visits during the 14 days after vaccination were compared with the risks of visits in 2 control periods. Significant plausible medically attended events identified in group 1 were then analyzed in group 2, using the same 2 control periods. Medically attended events significant in both groups were considered potentially associated with vaccination and were assessed by medical record review. SETTING: Five managed care organizations in the United States. PARTICIPANTS: Children younger than 18 years who received an influenza vaccination in one of the managed care settings (N = 251 600). MAIN OUTCOME MEASURE: Among vaccinated children seen for a medically attended event, the odds of the visit occurring in the 2 weeks after vaccination vs during 1 of the 2 control periods. RESULTS: Study participants incurred 1165, 230, and 489 different diagnoses during the 14 days after vaccination according to the outpatient, emergency department, and inpatient data, respectively. Four diagnoses were positively associated with the vaccine in both groups 1 and 2: impetigo, dermatitis, uncomplicated diabetes mellitus, and ureteral disorder not otherwise specified. After medical record review, impetigo (9 cases) in children 6 to 23 months old remained significantly associated with vaccination. CONCLUSION: This large screening safety study did not reveal any evidence of important medically attended events associated with pediatric influenza vaccination.

Case-Control Studies↗

PubMed2002

Public expectations and attitudes for annual physical examinations and testing.

BACKGROUND: Recent guidelines for adult prevention do not recommend a comprehensive annual physical examination, but current public expectations in light of this change are unknown. OBJECTIVE: To determine public belief in the need for and content of an annual physical examination and to examine the effect of financial charges on these beliefs. DESIGN: Telephone survey. SETTING: Three U.S. cities. PARTICIPANTS: Adult English-speaking respondents. MEASUREMENTS: Percentage of respondents answering that an annual physical examination is necessary and percentage desiring individual components of the history, physical examination, and laboratory testing, with and without knowledge of charges. RESULTS: Of 1203 respondents, 66% (67% in Denver, Colorado; 71% in Boston, Massachusetts; and 58% in San Diego, California) believed that in addition to regular care, an annual physical examination is necessary. Among the 600 respondents presented with charge information, interest decreased from 63% to 33% if payment were required. For history, greater than 90% believed that diet, exercise, and tobacco and alcohol use should be discussed, while 60% believed that seatbelt use and sexual history should be discussed. For the physical examination, greater than 90% felt that blood pressure should be measured and that the heart and lungs, abdomen, reflexes, and prostate should be examined. However, fewer than 80% thought that hearing and vision should be tested. Many tests, including the Papanicolaou smear (75%), mammography (71%), cholesterol measurement (65%), prostate-specific antigen test (65%), urinalysis (40%), blood glucose measurement (41%), fecal occult blood testing (39%), and chest radiography (36%), were desired. Interest in these tests decreased substantially when the charges were known. CONCLUSION: Public desire for a comprehensive annual physical examination is high across the United States and is sensitive to charges.

Adult↗

PubMedDate not supplied

The frequency and behavioral outcomes of goal choices in the self-management of diabetes.

PURPOSE: The purpose of this study was to determine the frequency and effectiveness of behavioral goal choices in the self-management of diabetes and to test goal-setting theory hypotheses that self-selection and behavioral specificity of goals are key to enhancing persistence. METHODS: Participants with type 2 diabetes in a randomized controlled trial (n = 422) completed baseline behavioral assessments using a clinic-based, interactive, self-management CD-ROM that allowed them to select a behavioral goal and receive mail and telephone support for the initial 6 months of the trial followed by additional behavioral assessments. Frequency of behavioral goal selection and 6-month behavioral data were collected. RESULTS: Approximately 49%, 27%, and 24% of the participants, respectively, set goals to increase physical activity (PA), reduce fat intake, or increase fruits and vegetables (F&V) consumed. At baseline, participants who selected PA, reduced fat consumption, or F&V were significantly, and respectively, less active, consumed more dietary fat, and ate fewer F&V regardless of demographic characteristics. Participants who selected a reduced-fat goal showed a significantly larger decrease than did those that selected PA or F&V goals. Participants who selected an F&V goal showed significant changes in F&V consumption. Participants who selected a PA goal demonstrated significant changes in days of moderate and vigorous physical activity. CONCLUSIONS: When participants are provided with information on health behavior status and an option of behavioral goals for managing type 2 diabetes, they will select personally appropriate goals, resulting in significant behavioral changes over a 6-month period.

Analysis of Variance↗

PubMedDate not supplied

Immunization registry-based recall for a new vaccine.

BACKGROUND: Immunization recall for specific vaccines may be necessary to "catch up" children with newly available vaccines or recall children after vaccine shortages. The extent to which immunization registry-based recall can increase immunization rates for a new vaccine has not been prospectively studied. OBJECTIVE: To assess the efficacy of letter/telephone recall for immunization with pneumococcal conjugate vaccine (PCV7) in an economically disadvantaged urban population. DESIGN/METHODS: Randomized controlled trial at an inner-city teaching hospital. Using an immunization registry, we randomly assigned children aged 6 weeks to 22 months unimmunized for PCV7 to an intervention group (n = 610) or a control group (n = 624). The intervention consisted of letter and telephone recall for PCV7 vaccination. Two months after intervention, receipt of 1 or more doses of PCV7 was assessed. Intention-to-treat analysis was used. RESULTS: We were unable to successfully contact 42.3% of the intervention subjects by mail and telephone. In the intervention group, 23.0% (140 children) received PCV7 within 2 months compared with 20.2% (126 children) in the control group (P = NS). No intervention effect was evident when children were stratified by age. A large proportion of the study population had Medicaid insurance (51.2%) or were uninsured (28.5%), but response to PCV7 recall did not vary by insurance status. CONCLUSIONS: Letter and telephone recall for PCV7 vaccine did not significantly increase the rate of PCV7 immunization in an inner-city teaching hospital serving a disadvantaged population. The effectiveness of recall appears to have been limited by the inability to reach many subjects by mail and telephone.

Child, Preschool↗