Biomedical subjects

William Barlow

Publications and source records attributed to William Barlow.

12 recordsLinked to original sources

PubMed2007

Surgeon and hospital characteristics as predictors of major adverse outcomes following colon cancer surgery: understanding the volume-outcome relationship.

HYPOTHESIS: Although numerous studies have demonstrated an association between surgical volume and improved outcome in cancer surgery, the specific structures and mechanisms of care that are associated with volume and lead to improved outcomes remain poorly defined. We hypothesize that there are modifiable surgeon and hospital characteristics that explain observed volume-outcome relationships. DESIGN: Retrospective cohort study. SETTING: Surveillance, Epidemiology, and End Results cancer registry areas. PATIENTS: Patients aged 66 years and older, diagnosed and surgically treated for stage I, II, or III colon cancer between 1992 and 1996 (n = 22 672). MAIN OUTCOME MEASURES: Thirty-day postoperative mortality and 30-day postoperative procedural interventions, including reoperation and image-guided percutaneous procedures. RESULTS: Surgeon volume, but not hospital volume, is a significant predictor of postoperative procedural intervention (adjusted odds ratio for very high-volume surgeons vs low-volume surgeons, 0.79; 95% confidence interval, 0.64-0.98). In the unadjusted analyses, high hospital volume (odds ratio, 0.67; 95% confidence interval, 0.56-0.81) and very high hospital volume (odds ratio, 0.65; 95% confidence interval, 0.54-0.79) is associated with lower postoperative mortality. Postoperative procedural intervention is not a significant mediator of the relationship between hospital volume and mortality. A single variable-the presence of sophisticated clinical services-was the most important explanatory variable underlying the relationship between hospital volume and mortality. CONCLUSIONS: Very high surgeon volume is associated with a reduction in surgical complications. However, the association between increasing hospital volume and postoperative mortality appears to derive mainly from a full spectrum of clinical services that may facilitate the prompt recognition and treatment of complications.

Adenocarcinoma↗

PubMed2006

Completion of therapy by Medicare patients with stage III colon cancer.

BACKGROUND: Certain factors, such as race or age, are known to be associated with variation in initiation of adjuvant chemotherapy for stage III colon cancer, but little is known about what factors are associated with completion of adjuvant therapy. To determine whether predictors of initiation also predict completion, we analyzed Surveillance, Epidemiology, and End Results (SEER) program data linked to Medicare claims. We investigated mortality as a means to testing the validity of the completion measure that we created. METHODS: We studied 3193 stage III colon cancer patients whose diagnosis was recorded in 1992-1996 SEER program data linked to 1991-1998 Medicare claims and who initiated adjuvant chemotherapy after colon cancer resection. We defined a measure of adjuvant chemotherapy completion as one chemotherapy administration claim in a month. We tested the validity of the created measure and its relation to 3-year cancer mortality adjusted for demographic, clinical, and environmental variables. We explored the association of patient characteristics and treating physician characteristics with chemotherapy completion by use of multivariable logistic regression modeling. RESULTS: Of the 3193 patients, 2497 (78.2%) completed the course. Risk of cancer-related mortality was statistically significantly lower among those completing chemotherapy (relative risk = 0.79, 95% confidence interval = 0.69 to 0.89) than those with no adjuvant therapy. Patients who were female, widowed, increasingly elderly, rehospitalized, and living in certain regions were less likely to complete adjuvant chemotherapy than other patients. Race and other clinical, environmental, and physician characteristics were not associated with completion of therapy. CONCLUSIONS: Factors associated with incomplete adjuvant chemotherapy may represent physical frailty, treatment complications, and lack of social and psychological support. Interventions to mitigate these influences are a logical next step toward increasing chemotherapy completion rates.

Aged↗

PubMed2006

Examining accuracy of screening mammography using an event order model.

Screening mammography is a widely used method for breast cancer detection. For each mammogram we propose a performance model based on order of outcomes. That is, we envision an initial assessment, a follow up assessment if the initial one is positive and, eventually, a determination of whether cancer was present or not. A model can be built at each stage reflecting effects due to patient characteristics, to the facility where mammogram was performed and to the radiologist reading the mammogram. Since assessment is not perfectly associated with outcome, familiar rates of agreement and disagreement are of interest. These rates can be investigated at various levels of risk factors of interest. The approach is illustrated with screening mammography data from the Group Health Cooperative in Seattle, WA. A Bayesian framework is adopted for inference and an analysis of the data set is presented.

Adult↗

PubMed2006

In search of the perfect comorbidity measure for use with administrative claims data: does it exist?

BACKGROUND: Numerous measures of comorbidity have been developed for health services research with administrative claims. OBJECTIVE: We sought to compare the performance of 4 claims-based comorbidity measures. RESEARCH DESIGN AND SUBJECTS: We undertook a retrospective cohort study of 5777 Medicare beneficiaries ages 66 and older with stage III colon cancer reported to the Surveillance, Epidemiology, and End Results Program between January 1, 1992 and December 31, 1996. MEASURES: Comorbidity measures included Elixhauser's set of 30 condition indicators, Klabunde's outpatient and inpatient indices weighted for colorectal cancer patients, Diagnostic Cost Groups, and the Adjusted Clinical Group (ACG) System. Outcomes included receipt of adjuvant chemotherapy and 2 year noncancer mortality. RESULTS: For all measures, greater comorbidity significantly predicted lower receipt of chemotherapy and higher noncancer death. Nested logistic regression modeling suggests that using more claims sources to measure comorbidity generally improves the prediction of chemotherapy receipt and noncancer death, but depends on the measure type and outcome studied. All 4 comorbidity measures significantly improved the fit of baseline regression models for both chemotherapy receipt (baseline c-statistic 0.776; ranging from 0.779 after adding ACGs and Klabunde to 0.789 after Elixhauser) and noncancer death (baseline c-statistic 0.687; ranging from 0.717 after adding ACGs to 0.744 after Elixhauser). CONCLUSIONS: Although some comorbidity measures demonstrate minor advantages over others, each is fairly robust in predicting both chemotherapy receipt and noncancer death. Investigators should choose among these measures based on their availability, comfort with the methodology, and outcomes of interest.

Aged↗

PubMed2006

Improving the concordance of mammography assessment and management recommendations.

PURPOSE: To retrospectively compare the concordance of initial and final assessment categories for mammograms with management recommendations made before and after the final rules of the Mammography Quality Standards Act (MQSA) were in effect for screening and diagnostic mammography. MATERIALS AND METHODS: The study included mammograms from 1996 to 2001 from the seven mammography registries of the Breast Cancer Surveillance Consortium (BCSC). The authors defined the pre-MQSA period as January 1, 1996-April 27, 1999, and the post-MQSA period as April 28, 1999-December 31, 2001 (2470151 screening and 194199 diagnostic mammograms). Assessment was cross-classified according to management recommendation. Changes in concordance between assessment and recommendation were evaluated by year and by period (before and after MQSA) for computer-linked data and for all data by using Pearson chi(2) test to evaluate differences. Mantel-Haenszel chi(2) test was used to measure change in concordance over time. Each registry and the BCSC Statistical Coordinating Center had a Federal Certificate of Confidentiality and approval from each institution's review board for protection of human subjects to collect and send data to coordinating center and conduct research with these data. Active consent was required at only one site in this HIPAA-compliant study. RESULTS: Concordance increased significantly in the post-MQSA period for Breast Imaging Reporting and Data System categories 3-5 assessments at both screening and diagnostic mammography. The most substantial improvements were in the use of the management recommendation for "additional imaging," which decreased from 41% in 1996 to 15% in 2001 for screening mammograms with an initial assessment of category 4 (P < .001). Recommendation for short-interval follow-up in women with screening mammograms with a category 3 final assessment increased from 51% in 1996 to 76% in 2001 (P < .001). Concordance for diagnostic mammograms assigned category 0 improved from 65% in the pre-MQSA period to 81% in the post-MQSA period (P < .001). CONCLUSION: This analysis demonstrates that over a relatively short period of time, major improvement in radiology reporting has occurred.

Breast Neoplasms↗

PubMed2006

Reality check: perceived versus actual performance of community mammographers.

OBJECTIVE: Federal regulations mandate that radiologists receive regular albeit limited feedback regarding their interpretive accuracy in mammography. We sought to determine whether radiologists who regularly receive more extensive feedback can report their actual performance in screening mammography accurately. SUBJECTS AND METHODS: Radiologists (n = 105) who routinely interpret screening mammograms in three states (Washington, Colorado, and New Hampshire) completed a mailed survey in 2001. Radiologists were asked to estimate how frequently they recommended additional diagnostic testing after screening mammography and the positive predictive value of their recommendations for biopsy (PPV2). We then used outcomes from 336,128 screening mammography examinations interpreted by the radiologists from 1998 to 2001 to ascertain their true rates of recommendations for diagnostic testing and PPV2. RESULTS: Radiologists' self-reported rate of recommending immediate additional imaging (11.1%) exceeded their actual rate (9.1%) (mean difference, 1.9%; 95% confidence interval [CI], 0.9-3.0%). The mean self-reported rate of recommending short-interval follow-up was 6.2%; the true rate was 1.8% (mean difference, 4.3%; 95% CI, 3.6-5.1%). Similarly, the mean self-reported and true rates of recommending immediate biopsy or surgical evaluation were 3.2% and 0.6%, respectively (mean difference, 2.6%; 95% CI, 1.8-3.4%). Conversely, radiologists' mean self-reported PPV2 (18.3%) was significantly less than their mean true PPV2 (27.6%) (mean difference, -9.3%; 95% CI, -12.4% to -6.2%). CONCLUSION: Despite regular performance feedback, community radiologists may overestimate their true rates of recommending further evaluation after screening mammography and underestimate their true positive predictive value.

Biopsy↗

PubMed2005

Explaining black-white differences in receipt of recommended colon cancer treatment.

BACKGROUND: Black-white disparities exist in receipt of recommended medical care, including colorectal cancer treatment. This retrospective cohort study examines the degree to which health systems (e.g., physician, hospital) factors explain black-white disparities in colon cancer care. METHODS: Data from the Surveillance, Epidemiology, and End Results program; Medicare claims; the American Medical Association Masterfile; and hospital surveys were linked to examine chemotherapy receipt after stage III colon cancer resection among 5294 elderly (> or = 66 years of age) black and white Medicare-insured patients. Logistic regression analysis was used to identify factors associated with black-white differences in chemotherapy use. All statistical tests were two-sided. RESULTS: Black and white patients were equally likely to consult with a medical oncologist, but among patients who had such a consultation, black patients were less likely than white patients (59.3% versus 70.4%, difference = 10.9%, 95% confidence interval [CI] = 5.1% to 16.4%, P < .001) to receive chemotherapy. This black-white disparity was highest among patients aged 66-70 years (black patients 65.7%, white patients 86.3%, difference = 20.6%, 95% CI = 10.7% to 30.4%, P < .001) and decreased with age. The disparity among patients aged 66-70 years also remained statistically significant in the regression analysis. Overall, patient, physician, hospital, and environmental factors accounted for approximately 50% of the disparity in chemotherapy receipt among patients aged 66-70 years; surgical length of stay and neighborhood socioeconomic status accounted for approximately 27% of the disparity in this age group, and health systems factors accounted for 12%. CONCLUSIONS: Black and white Medicare-insured colon cancer patients have an equal opportunity to learn about adjuvant chemotherapy from a medical oncologist but do not receive chemotherapy equally. Little disparity was explained by health systems; more was explained by illness severity, social support, and environment. Further qualitative research is needed to understand the factors that influence the lower receipt of chemotherapy by black patients.

Black or African American↗

PubMed2005

Community-based mammography practice: services, charges, and interpretation methods.

OBJECTIVE: The purpose of our study was to accurately describe facility characteristics among community-based screening and diagnostic mammography practices in the United States. MATERIALS AND METHODS: A survey was developed and applied to community-based facilities providing screening mammography in three geographically distinct locations in the states of Washington, Colorado, and New Hampshire. The facility survey was conducted between December 2001 and September 2002. Characteristics surveyed included facility type, services offered, charges for screening and diagnostic mammography, information systems, and interpretation methods, including the frequency of double interpretation. RESULTS: Among 45 responding facilities, services offered included screening mammography at all facilities, diagnostic mammography at 34 facilities (76%), breast sonography at 30 (67%), breast MRI at seven (16%), and nuclear medicine breast scanning at seven (16%). Most facilities surveyed were radiology practices in nonhospital settings. Eight facilities (18%) reported performing clinical breast examinations routinely along with screening mammography. Only five screening sites (11%) used computer-aided detection (CAD) and only two (5%) used digital mammography. Nearly two thirds of facilities interpreted screening mammography examinations on-site, whereas 91% of facilities interpreted diagnostic examinations on-site. Only three facilities (7%) interpreted screening examinations on line as they were performed. Approximately half of facilities reported using some type of double interpretation, although the methods of double interpretation and the fraction of cases double-interpreted varied widely across facilities. On average, approximately 15% of screening examinations and 10% of diagnostic examinations were reported as being double-interpreted. CONCLUSION: Comparison of this survey's results with those collected a decade earlier indicates dramatic changes in the practice of mammography, including a clear distinction between screening and diagnostic mammography, batch interpretation of screening mammograms, and improved quality assurance and medical audit tools. Diffusion of new technologies such as CAD and digital mammography was not widespread. The methods of double-interpretation and the fraction of cases double-interpreted varied widely across study sites.

Breast Neoplasms↗

PubMed2004

Biennial versus annual mammography and the risk of late-stage breast cancer.

BACKGROUND: Mammography screening may reduce breast cancer mortality by detecting cancers at an earlier stage. However, certain questions remain, including the ideal interval between mammograms. METHODS: We conducted an observational study using information collected by seven mammography registries across the United States to investigate whether women diagnosed with breast cancer after having screening mammograms separated by a 2-year interval (n = 2440) are more likely to be diagnosed with late-stage disease (positive lymph nodes or metastases) than women diagnosed with breast cancer after having screening mammograms separated by a 1-year interval (n = 5400). Analyses were stratified by age and breast density to clarify whether groups that have the poorest mammography sensitivity (i.e., women under age 50 years and those with mammographically dense breasts) would benefit most from annual screening. The subjects were women diagnosed with breast cancer between 1996 and 2001 who were 40-89 years old at their index mammographic examination (i.e., the most recent screen at or before breast cancer diagnosis). Data were analyzed by logistic regression, adjusting for race, ethnicity, family history of breast cancer, and mammography registry. RESULTS: Among women age 40-49 years at the index mammogram, those with a 2-year screening interval were more likely to have late-stage disease at diagnosis than those with a 1-year screening interval (28% versus 21%; odds ratio [OR] = 1.35, 95% confidence interval [CI] = 1.01 to 1.81). There was no increase in late-stage disease for women 50 years or older with a 2-year versus a 1-year screening interval (women age 50-59 years at index mammogram: OR = 0.97, 95% CI = 0.75 to 1.25; women age 60-69 years at index mammogram: OR = 0.99, 95% CI = 0.72 to 1.35; women age 70 years or older at index mammogram: OR = 0.88, 95% CI = 0.64 to 1.19). There was no indication that women with dense breasts would benefit more from a 1-year versus 2-year screening interval than women with fatty breasts. CONCLUSION: These findings may be useful for policy decisions about appropriate screening intervals and for use in statistical models that estimate the costs and benefits of mammography by age and screening interval.

Adult↗

PubMed2003

Placing the risk of seizures with pediatric vaccines in a clinical context.

In this review we discuss the relationship between commonly administered childhood vaccines such as diphtheria-tetanus-whole cell pertussis (DTP) and measles-mumps-rubella (MMR), and the risk of nonfebrile and febrile seizure. We summarize data from the Vaccine Safety Datalink Study and other studies that suggest that DTP and MMR vaccine are associated with a transiently increased risk of febrile seizures, and cause between 5-9 and 25-34 additional extra febrile seizures per 100 000 immunized children, respectively. DTP and MMR do not appear to increase the risk of nonfebrile seizures. We discuss some methodologic challenges in studies of vaccines and seizures. Because there is no adequate comparison group that would allow for the study of seizures long after vaccination, studies of seizures are limited to acute events shortly following vaccination. Additionally, while seizures following vaccination are worrisome to parents and physicians alike, observational studies of the neurodevelopmental outcomes of these children are particularly problematic. We discuss how such studies are confounded by the natural history of predisposition to febrile seizures and by the increased diagnostic scrutiny that children with febrile seizures might undergo. Nevertheless, current data suggest that children with febrile seizures do not experience long-term negative effects.Finally, we discuss the creation of new clinics designed specifically to assist physicians in managing the vaccination of children with a personal or family history of seizures. Data from these clinics suggest that vaccination is safe for children with a personal or family history of seizures, but statistical power has been limited. We conclude by discussing the introduction of new vaccines, and note that, even with widespread use, it will take many years before we can be knowledgeable about the risk of rare events with these newly licensed products.

Child↗

PubMed2003

Estrogen therapy and risk of cardiovascular events among women with type 2 diabetes.

OBJECTIVE: To evaluate the association between estrogen therapy and cardiovascular disease risk among women with type 2 diabetes. RESEARCH DESIGN AND METHODS: A retrospective, case-cohort study was conducted among 6017 women aged 45-80 years with type 2 diabetes from 1 January 1986 to 31 December 1992 at the Group Health Cooperative in Washington state. Cardiovascular outcomes, including nonfatal myocardial infarction (n = 215), coronary revascularization (n = 253), and cardiovascular deaths (n = 229), were ascertained through 31 December 1998. Use of estrogen and progestin was derived from automated pharmacy records and modeled as a time-dependent variable. Median follow-up was 6.8 years. Multivariable-adjusted relative risk (RR) and 95% CI were calculated using Cox proportional hazard models for case-cohort analyses. RESULTS: Current use of estrogen with (RR 0.43, 95% CI 0.22-0.85) or without (0.48, 0.30-0.78) progestin was associated with a decreased risk of cardiovascular events compared with never having used estrogen. Risk of cardiovascular events associated with a first episode of estrogen use (with or without progestin) of <25 months' duration (1.12, 0.49-2.54), first episode of use >or=25 months' duration (0.32, 0.06-1.70), and current use that was not the first episode of use (0.42, 0.42-0.67) indicated that recent initiation was not associated with an increase or decrease in risk. CONCLUSIONS: These results show an association of estrogen therapy, with or without progestin, with decreased risk of cardiovascular events among women with type 2 diabetes. This association should be further investigated in large randomized, controlled trials.

Adult↗

PubMed2002

Hormone replacement therapy in relation to breast cancer.

CONTEXT: Studies of long-term hormone replacement therapy (HRT) suggest an associated increased risk of breast cancer, but whether this association differs according to histologic type of cancer has not been extensively studied. OBJECTIVE: To determine whether the association between HRT and risk of breast cancer varies by HRT formulation and differs across histologic cancer types. DESIGN, SETTING, AND PARTICIPANTS: Nested case-control study among 705 postmenopausal women enrolled in the Group Health Cooperative of Puget Sound (GHC) who were aged 50 to 74 years and had primary invasive breast cancer diagnosed between July 1, 1990, and December 31, 1995 (cases), and 692 randomly selected aged-matched female members of GHC (controls). MAIN OUTCOME MEASURE: Incidence and type of breast cancer by duration of HRT use in the 5-year period ending 1 year before diagnosis, which was ascertained from computerized pharmacy records. RESULTS: The incidence of breast cancer, all histologic types combined, was increased by 60% to 85% in recent long-term users of HRT, whether estrogen alone or estrogen plus progestin. Longer use of HRT (odds ratio [OR], 3.07 for 57 months or more; 95% confidence interval [CI], 1.55-6.06) and current use of combination therapy (OR, 3.91; 95% CI, 2.05-7.44) were associated with increased risk of lobular breast cancer. Long-term HRT use was associated with a 50% increase in nonlobular cancer (OR, 1.52 for 57 months or more; 95% CI, 1.01-2.29). CONCLUSION: Our data add to the growing body of evidence that recent long-term use of HRT is associated with an increased risk of breast cancer and that such use may be related particularly to lobular tumors.

Aged↗