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Biomedical subjects

Peter B Bach

Publications and source records attributed to Peter B Bach.

At least 37 records · Page 2Linked to original sources
PubMed2004

The impact of complications on outcomes after resection for esophageal and gastroesophageal junction carcinoma.

BACKGROUND: Efforts to improve surgical outcomes have traditionally focused on improving preoperative patient selection and reducing the risk of postoperative medical complications. Strategies to optimize surgical technique have been less well studied. We sought to assess the relation between complications related to surgical technique and outcomes after esophagogastrectomy for cancer. STUDY DESIGN: Medical records of 510 consecutive patients undergoing esophagogastrectomy for invasive squamous cell carcinoma or adenocarcinoma at Memorial Sloan-Kettering Cancer Center from 1996 to 2001 were reviewed. Data on diagnosis, stage of disease, therapies received, surgical approach, patient comorbidities, technical complications, and postoperative medical complications and outcomes including length of stay and overall survival were determined by one reviewer of the medical records. The primary predictor was surgical complications and the primary outcome was survival. RESULTS: Of the 150 patients studied 138 (27%) had complications directly attributable to surgical technique, such as an anastomotic leak, a paralyzed vocal cord, or chylothorax. At 3 years 43 of 138 patients (31%) with technical complications were alive, whereas 179 of 372 patients (48%) without technical complications were alive. Technical complications were associated with increased length of stay (median 23 days versus 11 days, p < 0.001), increased in-hospital mortality (12.3% versus 3.8%, p < 0.001), and a higher rate of medical complications (77.5% versus 47.3%, p < 0.001). After controlling for age, medical comorbidities, use of induction therapy, tumor stage, histology, and location, and completeness of resection the presence of a technical complication was highly predictive of poorer overall survival; the multivariable hazard ratio was 1.41 (1.22 to 1.63, p = 0.008). CONCLUSIONS: Technical complications have a large negative impact on survival after esophagogastrectomy for cancer. Strategies to optimize surgical technique and minimize complications should improve outcomes in this cancer operation.

Adenocarcinoma↗
PubMed2004

Benchmarking lung cancer mortality rates in current and former smokers.

STUDY OBJECTIVES: To develop and validate a model for estimating the risk of lung cancer death in current and former smokers. The model is intended for use in analyzing a population of subjects who are undergoing lung cancer screening or receiving lung cancer chemoprevention, to determine whether the intervention has altered lung cancer mortality. DESIGN/SETTING/PATIENTS: Model derivation was based on analyses of the placebo arm of the Carotene and Retinol Efficacy Trial. Model validation was based on analyses of three other longitudinal cohorts. MEASUREMENTS: Observed and predicted number of deaths due to lung cancer. RESULTS: In internal validation, the model was highly concordant and well calibrated. In external validation, the model predictions were similar to what was observed in all of the validation analyses. The predicted and observed deaths within 6 years were very similar when assessed in the Johns Hopkins Hospital trial of chest radiography and sputum cytology screening (176 predicted, 184 observed, p = 0.53), the Memorial Sloan-Kettering Cancer Center trial of chest radiography and sputum cytology screening (108 predicted, 114 observed, p = 0.57), and the National Health and Nutrition Evaluation Survey part I (24 predicted, 21 observed, p = 0.52). CONCLUSIONS: The number of lung cancer deaths in a population of current or former smokers can be accurately predicted, making model-based evaluations of prevention and early detection interventions a useful adjunct to definitive randomized trials. We illustrate this potential use with a small example.

Adult↗
PubMed2003

The effect of clustering of outcomes on the association of procedure volume and surgical outcomes.

BACKGROUND: A large body of literature documents associations between the volume of cases a hospital or surgeon treats and clinical outcomes. Most of these studies have used conventional statistical methods that do not recognize the fact that hospitals or surgeons with similar volumes may have very different outcomes because of systematic differences in processes of care, a phenomenon that exaggerates the true statistical significance of the effect of volume on outcome. OBJECTIVE: To describe methods to assess the degree of this "clustering" of outcomes and to explore the impact of available statistical techniques that correct for clustering. DESIGN: Reanalysis of 3 previously published volume-outcome studies. SETTING: Medicare beneficiaries 65 years of age or older undergoing surgery for colon, prostate, or rectal cancer in the population defined by the Surveillance, Epidemiology, and End Results cancer registries during 1992 to 1996. PATIENTS: 3 data sets were analyzed to assess the impact of surgeon volume on outcomes: 1) 24 166 colectomies performed by 2682 surgeons, 2) 10 737 prostatectomies performed by 999 surgeons, and 3) 2603 rectal resections performed by 1141 surgeons. MEASUREMENTS: Volume-outcome trends were analyzed by a conventional method (logistic regression) and corrected for clustering. Two widely used statistical methods for analyzing clustered data, a random-effects model and generalized estimating equations, were used and compared, and the degree of clustering was presented graphically. RESULTS: Substantial clustering was observed in the analyses involving morbidity end points. The 2 statistical techniques produced noticeably different results in some analyses. CONCLUSIONS: The presence of clustering represents variations in outcomes among providers with similar volumes. Thus, in volume-outcome studies, the degree of clustering of outcomes should be characterized because it may provide insight into variations in quality of care.

Clinical Competence↗
PubMed2003

Adherence to surveillance among patients with superficial bladder cancer.

BACKGROUND: Patients diagnosed with superficial bladder cancer who have not undergone total cystectomy are at high risk for recurrence, and bladder surveillance with cystoscopy is recommended for such patients every 3-6 months. We examined the degree to which bladder cancer patients undergo the recommended surveillance procedures and identified patient and primary care provider characteristics associated with nonadherence to these recommendations. METHODS: We used information obtained from the Surveillance, Epidemiology, and End Results (SEER) Program-Medicare-linked database to identify 6717 patients aged 65 years or older who were diagnosed with superficial bladder cancer from 1992 through 1996 and who survived for at least 3 years after diagnosis but did not have a total cystectomy. We used information obtained from Medicare claims forms to examine the frequency with which these patients had a surveillance examination of the bladder during each of five contiguous 6-month intervals from month 7 to month 36 following diagnosis. We examined characteristics of patients and their physicians that were associated with low-intensity surveillance (defined as having an examination during fewer than two of the five possible follow-up intervals). Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). All statistical tests were two-sided. RESULTS: Only 40% of the entire cohort had an examination during all five intervals; 1216 patients (18.1%) had low-intensity surveillance. Patient characteristics that were independently associated with low-intensity surveillance were being age 75 years or older (adjusted OR = 1.54, 95% CI = 1.35 to 1.74), nonwhite (adjusted OR = 1.94, 95% CI = 1.57 to 2.40), and having favorable tumor histology (adjusted OR = 0.59, 95% CI = 0.48 to 0.72 for poorly differentiated versus referent well-differentiated tumor grade) and high comorbidity (adjusted OR = 1.72, 95% CI = 1.30 to 2.27). Residence in an urban area or in a census tract with low median income was also associated with low-intensity surveillance. CONCLUSIONS: The actual practice of surveillance for patients with superficial bladder cancer differs substantially from the standards recommended in clinical guidelines.

Aged↗
PubMed2003

Variations in lung cancer risk among smokers.

BACKGROUND: Although there is no proven benefit associated with screening for lung cancer, screening programs are attracting many individuals who perceive themselves to be at high risk due to smoking. We sought to determine whether the risk of lung cancer varies predictably among smokers. METHODS: We used data on 18 172 subjects enrolled in the Carotene and Retinol Efficacy Trial (CARET)-a large, randomized trial of lung cancer prevention-to derive a lung cancer risk prediction model. Model inputs included the subject's age, sex, asbestos exposure history, and smoking history. We assessed the model's calibration by comparing predicted and observed rates of lung cancer across risk deciles and validated it by assessing the extent to which a model estimated on data from five CARET study sites could predict events in the sixth study site. We then applied the model to evaluate the risk of lung cancer among smokers enrolled in a study of lung cancer screening with computed tomography (CT). RESULTS: The model was internally valid and well calibrated. Ten-year lung cancer risk varied greatly among participants in the CT study, from 15% for a 68-year-old man who has smoked two packs per day for 50 years and continues to smoke, to 0.8% for a 51-year-old woman who smoked one pack per day for 28 years before quitting 9 years earlier. Even among the subset of CT study participants who would be eligible for a clinical trial of cancer prevention, risk varied greatly. CONCLUSIONS: The risk of lung cancer varies widely among smokers. Accurate risk prediction may help individuals who are contemplating voluntary screening to balance the potential benefits and risks. Risk prediction may also be useful for researchers designing clinical trials of lung cancer prevention.

Aged↗
PubMed2003

Perspectives on the value of American Society of Clinical Oncology clinical guidelines as reported by oncologists and health maintenance organizations.

PURPOSE: Although the American Society of Clinical Onoclogy's (ASCO) Health Services Research (HSR) committee activities have primarily focused on clinical guideline development, little is known about the value placed on these guidelines by the desired end users. ASCO members and Health Maintenance Organizations (HMOs) were surveyed on the value and implementation of ASCO guidelines. In this article, we summarize our findings. METHODS: ASCO members (n = 1500) were queried about whether they had read ASCO's first four clinical guidelines and technology assessment; whether they agreed with the recommendations; whether they used guidelines in clinical practice; and how guidelines had affected reimbursement. HMOs (n = 131) were queried on how they identify, implement, and value the first four ASCO clinical guidelines. RESULTS: The membership survey indicated that ASCO guidelines were read more often by physicians in private healthcare settings compared with physicians in academic practices (P <.02). Disagreement rates were low for all guidelines (range, 1% to 7%). One quarter of respondents reported that the guidelines were difficult to find and difficult to apply to the practice setting, and approximately one tenth of respondents indicated that the guidelines were difficult to evaluate, interpret, or read. The HMO survey indicated that one third of HMOs reported use of ASCO guidelines, with higher rates of usage by larger HMOs and by those with higher National Committee on Quality Assurance (NCQA) ratings. Respondent HMOs valued guidelines for various purposes and used multiple methods of guideline identification and implementation. CONCLUSION: ASCO guidelines are generally highly supported by physicians and HMOs. Additional studies are needed to identify implementation barriers and to see whether guidelines have resulted in improvements in healthcare.

Attitude of Health Personnel↗
PubMed2003

Surgeon volume compared to hospital volume as a predictor of outcome following primary colon cancer resection.

BACKGROUND AND OBJECTIVES: A strong association between high hospital procedure volume and survival following colon cancer resection has been demonstrated. However, the importance of surgeon case volume as a determinant of outcome has been less well studied, and it is unclear whether hospital or surgeon volume is the more powerful predictor of outcomes. METHODS: A retrospective population-based cohort study utilizing the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database identified 24,166 colon cancer patients aged 65 years and older who had surgery for a primary tumor diagnosed in 1991-1996 in a SEER area. Hospital and surgeon-specific procedure volume was ascertained based on the number of claims submitted over the 6-year study period. Outcome measures were mortality at 30 days and 2 years, overall survival, and the frequency of operations requiring an intestinal stoma. Age, sex, race, comorbid illness, cancer stage, socioeconomic status, emergent hospitalization, and the presence of obstruction/perforation were used to adjust for differences in case-mix. RESULTS: After adjusting for surgeon procedure volume, high hospital procedure volume remained a strong predictor of low post-operative mortality rates (P < 0.001 for each outcome with and without adjustment for surgeon procedure volume). Surgeon-specific procedure volume was also an important predictor of surgical outcomes (P = 0.002 for 30-day mortality, P = 0.001 for 2-year mortality), although this effect was attenuated after adjusting for hospital volume (P = 0.03 for 30-day mortality, P = 0.02 for 2-year mortality). Hospital volume and surgeon volume were each an important predictor of the ostomy rate. Among high volume institutions and surgeons, individual providers with unusually high ostomy rates could be identified. CONCLUSIONS: Both hospital and surgeon-specific procedure volume predict outcomes following colon cancer resection; but hospital volume may exert a stronger effect. Therefore, efforts to optimize the quality of colon cancer surgery should focus on multidisciplinary aspects of hospital care rather than solely on intraoperative technique.

Aged↗
PubMed2003

Arterial desaturation syndrome following pleurodesis with talc slurry: incidence, clinical features, and outcome.

The objectives were to define the incidence, risk factors, clinical features and outcome of arterial desaturation syndrome following talc pleurodesis in patients with malignant pleural effusions. This retrospective, observational study took place at a tertiary care cancer center in New York. All patients were those with malignancy who underwent pleurodesis with talc in 1998 at Memorial Sloan Kettering Cancer Center. Characteristics of patients are described by using summary statistics. Differences between groups were assessed with the Fisher's exact statistic for categorical variables and Student's t-test for continuous variables. Among patients who were considered to have arterial desaturation syndrome, we evaluated the relation of SaO2/FIO2 pre- and post-talc installation using a paired Student's t-test. During 1998, 120 patients underwent pleurodesis with talc, and 8 (7%) developed arterial desaturation following the procedure. Symptoms included chest pain, dyspnea, fever, and increased need for oxygen supplementation developed typically within 1 day. Three of the eight patients in this series required mechanical ventilation, but all recovered uneventfully after treatment, which included high-dose corticosteroids. Patients with breast and ovarian cancer appeared to be at increased risk for this complication compared to those patients with other types of cancer (p = 0.01). Approximately 7% of patients who have undergone sclerosis with talc for a malignant pleural effusion will develop arterial desaturation with clinically significant hypoxia requiring supplemental oxygen following the procedure. It appears that most patients recover from this complication and that those with breast and ovarian cancer may be at higher risk.

Adrenal Cortex Hormones↗
PubMed2003

Screening for lung cancer: a review of the current literature.

STUDY OBJECTIVES: To review the available data on the early detection of lung cancer, with a focus on three technologies: chest x-ray (CXR), sputum cytology, and low-dose CT (LDCT) scanning. DESIGN, SETTING, PARTICIPANTS: Review of published clinical studies of early detection technologies. The best available evidence on each topic was selected for analysis. Randomized trials were used to evaluate CXR and sputum cytology. Cohort studies, as well as studies providing evidence regarding rates of overdiagnosis and efficacy of initial treatment, were considered in evaluation of LDCT. Study design and results were summarized in evidence tables. Statistical analyses of combined data were not performed. MEASUREMENT AND RESULTS: Five randomized trials of CXR with or without sputum cytology have been conducted, each which reports disease-specific mortality as well as other end points. None of these studies provide support for the use of either CXR or sputum cytology for the early detection of lung cancer in asymptomatic individuals. Eight completed and ongoing trials of LDCT were identified. All of these studies report the frequency and stage distribution of lung cancers found during initial ("prevalence") screening, and several studies also report rates of detection at the time of annual follow-up. No outcome data on survival or treatment are available. A number of studies support the hypothesis of "overdiagnosis"--that some lung cancers detected by LDCT may behave in an indolent manner. CONCLUSIONS: The use of either CXR or sputum cytology for the early detection of lung cancer is not supported by the published evidence. The evidence for LDCT appears promising, in that the technology typically identifies lung cancer at an early stage, although corollary studies suggest that these findings in isolation may be misleading. Further high-quality research is needed to better define the role of LDCT in the evaluation of asymptomatic high-risk individuals.

Cohort Studies↗
PubMed2003

Screening for lung cancer: the guidelines.

Although virtually all individuals with advanced lung cancer succumb to the disease, a substantial portion of individuals diagnosed at an earlier stage can be cured. This dichotomy has provoked interest in lung cancer screening. To date, randomized controlled trials of chest x-ray and sputum cytology have failed to demonstrate that screening with either modality decreases lung cancer mortality; neither of these technologies can be recommended. Early studies of lung cancer screening with low-dose CT (LDCT) appear promising; however, only data from observational studies are available. We recommend that individuals should only be screened with LDCT in the context of well-designed clinical trials.

Evidence-Based Medicine↗
PubMed2002

State expenditures for tobacco-control programs and the tobacco settlement.

BACKGROUND: Despite controversy surrounding the use of funds arising from settlement agreements with the tobacco industry, little is known about the role of these funds in expenditures for state tobacco-control programs. METHODS: We evaluated state expenditures for tobacco-control programs in fiscal year 2001 in the context of the amount of tobacco-settlement funds received and allocated to tobacco-control programs and in the context of other state-level economic and health data. RESULTS: In 2001 the average state received $28.35 per capita from the tobacco settlement but allocated approximately 6 percent of these funds to tobacco-control programs. The average state dedicated $3.49 per capita (range, $0.10 to $15.47) to tobacco-control programs. The proportion of settlement funds allocated to tobacco-control programs varied from 0 to 100 percent and was strongly related to levels of tobacco-control funding (P<0.001). States with higher smoking rates tended to invest less per capita in tobacco-control programs (P=0.007), as did tobacco-producing states (the mean per capita expenditure was $1.20, as compared with $3.81 in non-tobacco-producing states; P<0.008). In a multivariate analysis, the proportion of the settlement revenue allocated to tobacco-control programs was the primary determinant of the level of total funding; the state tobacco-related health burden was unrelated to program funding. CONCLUSIONS: State health needs appear to have little effect on the funding of state tobacco-control programs. Because only a very small proportion of the tobacco settlement is being used for tobacco-control programs, the settlement represents an unrealized opportunity to reduce morbidity and mortality from smoking.

Health Expenditures↗
PubMed2002

Adjuvant chemotherapy use for Medicare beneficiaries with stage II colon cancer.

PURPOSE: Clinical trials have not demonstrated that adjuvant chemotherapy improves survival for patients with resected stage II colon cancer. Nevertheless, patients may receive this treatment despite its uncertain benefit. The objective of this study was to determine the extent to which adjuvant chemotherapy is used for patients with stage II colon cancer. PATIENTS AND METHODS: Using the Surveillance, Epidemiology, and End Results-Medicare linked database, we identified 3,151 patients aged 65 to 75 with resected stage II colon cancer and no adverse prognostic features. The primary outcome was chemotherapy use within 3 months of surgery ascertained from claims submitted to Medicare. Relationships between patient characteristics and adjuvant chemotherapy use were measured and their significance was assessed using multivariable logistic regression. Survival for treated and untreated patients was compared using a Cox model. RESULTS: Twenty-seven percent of patients received chemotherapy during the 3 postoperative months. Younger age at diagnosis, white race, unfavorable tumor grade, and low comorbidity were each associated with a greater likelihood of receiving treatment. Sex, the number of examined lymph nodes in the tumor specimen, the urgency of the surgical admission, and median income was each unrelated to treatment. Five-year survival was 75% for untreated patients and 78% for treated patients. After adjusting for known between-group differences, the hazard ratio for survival associated with adjuvant treatment was 0.91 (95% confidence interval, 0.77 to 1.09). CONCLUSION: A substantial percentage of Medicare beneficiaries with resected stage II colon cancer receive adjuvant chemotherapy despite its uncertain benefit.

Aged↗
PubMed2002

Survival of blacks and whites after a cancer diagnosis.

CONTEXT: In recent years a theory that cancer biology is different in blacks and whites has gained prominence in reaction to epidemiologic observations that blacks have poorer survival than whites, even when diagnosed with cancer of similar severity. Yet, few studies have evaluated whether lower-quality treatment and shorter overall life expectancy due to a greater burden of other illnesses may explain the survival discrepancy. OBJECTIVE: To estimate the magnitude of overall and cancer-specific survival differences between blacks and whites who receive comparable treatment for similar-stage cancer. DATA SOURCES: We searched MEDLINE for English-language articles published from 1966 to January 2002 that reported on overall survival for black and white patients treated similarly for cancer. STUDY SELECTION: The abstracts or titles for 891 citations were independently examined by 2 authors. The full text was retrieved if the abstract mentioned both black and white patients, made some comment regarding either similarity of treatment received or presented an analysis based on the treatment received, and commented on survival. Studies were included if they included data for at least 10 black and 10 white patients; specified the cohort ascertainment method and what measures were undertaken to minimize loss to follow-up; summarized survival of both blacks and whites using actuarial measures; presented outcomes within stage, adjusted for stage, or based on cohorts with balanced stage distributions; and specified that blacks and whites in the study received similar treatment. We identified 89 unique cohorts in 54 articles that met our inclusion criteria. DATA EXTRACTION: Overall survival rates and hazard ratios (HRs) for death for blacks relative to whites were calculated. These were subsequently adjusted for rates of death due to causes other than the cancer under study to determine cancer-specific survival and cancer-specific HRs. DATA SYNTHESIS: Results represent 189 877 white and 32 004 black patients with 14 different cancers. Compared with whites, blacks had an overall excess risk of death (HR, 1.16; 95% confidence interval [CI], 1.12-1.20). After correction for deaths due to other causes, the cancer-specific HR was 1.07 (95% CI, 1.02-1.13). Of the 14 cancers, blacks were at a significantly higher risk of cancer-specific death only for cancer of the breast, uterus, or bladder. CONCLUSIONS: Only modest cancer-specific survival differences are evident for blacks and whites treated comparably for similar-stage cancer. Therefore, differences in cancer biology between racial groups are unlikely to be responsible for a substantial portion of the survival discrepancy. Differences in treatment, stage at presentation, and mortality from other diseases should represent the primary targets of research and interventions designed to reduce disparities in cancer outcomes.

Black or African American↗
PubMed2002

Variations in morbidity after radical prostatectomy.

BACKGROUND: Recent studies of surgery for cancer have demonstrated variations in outcomes among hospitals and among surgeons. We sought to examine variations in morbidity after radical prostatectomy for prostate cancer. METHODS: We used the Surveillance, Epidemiology, and End Results-Medicare linked data base to evaluate health-related outcomes after radical prostatectomy. The rates of postoperative complications, late urinary complications (strictures or fistulas 31 to 365 days after the procedure), and long-term incontinence (more than 1 year after the procedure) were inferred from the Medicare claims records of 11,522 patients who underwent prostatectomy between 1992 and 1996. These rates were analyzed in relation to hospital volume and surgeon volume (the number of procedures performed at individual hospitals and by individual surgeons, respectively). RESULTS: Neither hospital volume nor surgeon volume was significantly associated with surgery-related death. Significant trends in the relation between volume and outcome were observed with respect to postoperative complications and late urinary complications. Postoperative morbidity was lower in very-high-volume hospitals than in low-volume hospitals (27 percent vs. 32 percent, P=0.03) and was also lower when the prostatectomy was performed by very-high-volume surgeons than when it was performed by low-volume surgeons (26 percent vs. 32 percent, P<0.001). The rates of late urinary complications followed a similar pattern. Results for long-term preservation of continence were less clear-cut. In a detailed analysis of the 159 surgeons who had a high or very high volume of procedures, wide surgeon-to-surgeon variations in these clinical outcomes were observed, and they were much greater than would be predicted on the basis of chance or observed variations in the case mix. CONCLUSIONS: In men undergoing prostatectomy, the rates of postoperative and late urinary complications are significantly reduced if the procedure is performed in a high-volume hospital and by a surgeon who performs a high number of such procedures.

Aged↗
PubMed2002

The epidemiology and costs of chronic critical illness.

CCI patients are patients who have suffered acute illness or injury and require life support or care in an ICU setting for periods of weeks or months. These patients account for between 5% and 10% of ICU admissions, and they appear to be increasing in number. Over half of the patients are over age 65. Patients with underlying premorbid conditions who suffer complications of acute illness are at highest risk for becoming CCI. These patients have poor short-term and long-term survival, although survival may be improving for some types of CCI patients as the medical system adapts to their specific needs. Long-term survival is associated with age and premorbid condition or functional status. Survivors have significant functional limitations, but their reported quality of life is generally good. CCI patients consume a disproportionate share of ICU and hospital resources, and significant additional resources are required for continued recovery or care after discharge. Specialized units have been evolving to manage these patients at lower costs than in acute ICUs, and with similar outcomes. Further refinement of the definition of CCI is an important objective, and should pave the way to better design of outcomes studies. Efforts should continue to learn how to identify patients at high risk for CCI and poor outcome so that expensive resources can be managed effectively, and patient-provider decision making can be better informed.

Adult↗