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Biomedical subjects

P B Bach

Publications and source records attributed to P B Bach.

At least 19 recordsLinked to original sources
PubMed2002

Bronchiolitis obliterans organizing pneumonia in cancer: a case series.

Bronchiolitis obliterans with organizing pneumonia (BOOP) is an infrequently encountered clinical condition that can mimic a number of other pathologic lung processes. The presentation of this treatable condition in cancer patients has not been described in any large series. We conducted a retrospective study of patients with BOOP at Memorial Sloan-Kettering Cancer Center, NewYork, NY, U.S.A. from January 1992 to December 1999. The type and treatment of primary cancer, clinical and radiographic features of initial BOOP presentation, and outcome following therapy were recorded. Forty-three patients with an underlying diagnosis of cancer were found on lung biopsy to have BOOP as an isolated entity. BOOP was encountered in patients with a variety of clinical presentations, and many types of malignancies. The symptom patterns were non-specific, as were the physiological abnormalities. The only clear relationship between the underlying malignancyand the diagnosis of BOOP at presentation was in the chest radiographic findings. Patients with solid organ tumors were more likely to have nodular or mass like radiographic abnormalities (81%) than to have diffuse infiltrates (19%). We observed the opposite pattern in patients with hematologic malignancies (22% vs.67%). The vast majority of patients recovered from this condition. In conclusion, For cancer patients, BOOP represents a treatable cause of lung disease with protean manifestations. BOOP can mimic pulmonary malignancy and pulmonary infection. In cancer patients, the evaluation of new pulmonary symptoms accompanied by radiographic changes should include a consideration of this diagnosis.

Adult↗
PubMed2001

Identification of poor prognostic features among patients requiring mechanical ventilation after hematopoietic stem cell transplantation.

Patients who develop respiratory failure requiring mechanical ventilation after hematopoietic stem cell transplantation (HSCT) have very high mortality. Several investigators have identified prognostic features that can be used to identify a subset of these patients who are virtually certain to die, yet these have never been prospectively assessed. The objectives of this study were to determine the accuracy of published prognostic features for mortality and to determine the survival of patients who recover from respiratory failure. A systematic review of the literature was undertaken to identify reported poor prognostic features and survival rates. The study validated the reported poor prognostic features on a prospective, multicenter inception cohort of 226 patients with respiratory failure requiring mechanical ventilation after HSCT. The main outcome measures were determination of a baseline probability of death, drawn from literature review; likelihood ratio of mortality for each prognostic feature determined from the validation cohort; conditional probability of death in the presence of each feature; and 6-month survival of those who recover. Patients requiring mechanical ventilation after HSCT have a baseline probability of death of 82% to 96%. In the setting of combined hepatic and renal dysfunction, the probability of death rises to 98% to 100%. Other previously reported prognostic features are less strongly associated with mortality. For patients who recover from respiratory failure, the proportion surviving 6 months or longer ranges from 27% to 88%. It was concluded that in patients requiring mechanical ventilation after HSCT, the presence of combined hepatic and renal dysfunction is highly predictive of death. The presence of this feature may justify the recommendation to withdraw life-sustaining measures.

Adult↗
PubMed2001

Who gets adjuvant treatment for stage II and III rectal cancer? Insight from surveillance, epidemiology, and end results--Medicare.

PURPOSE: To examine the relationship between patient characteristics and the use of adjuvant pelvic radiation with and without chemotherapy among patients aged 65 years and older with stage II and III rectal cancer. PATIENTS AND METHODS: A retrospective cohort study using the Surveillance, Epidemiology, and End Results-Medicare linked database identified 1,411 patients aged 65 and older with resected stage II and III rectal cancers diagnosed between 1992 and 1996. From claims submitted to Medicare, we measured the use of pelvic radiation therapy with or without chemotherapy and pre- or postoperatively. RESULTS: Fifty-seven percent of patients received radiation, 42% received chemotherapy and radiation, and 7% had treatment delivered preoperatively. Age was the strongest determinant of treatment: 73% of patients aged 65 to 69, 66% aged 70 to 75, 52% aged 75 to 79, 39% aged 80 to 84, and 21% aged 85 to 89 received radiation. The age trend remained strong after adjusting for other factors that predict receipt of treatment and after exclusion of patients with any evident comorbidity (P <.001). Patients were more likely to receive radiation treatment if they had an abdominal perineal resection, stage III disease, or a T4 tumor. CONCLUSION: Because pelvic recurrences are a substantial cause of morbidity, further efforts are needed to ensure that elderly patients have the opportunity to make informed decisions regarding adjuvant treatment.

Age Factors↗
PubMed2001

The influence of hospital volume on survival after resection for lung cancer.

BACKGROUND: Among patients who have undergone high-risk operations for cancer, postoperative mortality rates are often lower at hospitals where more of these procedures are performed. We undertook a population-based study to estimate the extent to which the number of procedures performed at a hospital (hospital volume) is associated with survival after resection for lung cancer. METHODS: We studied patients 65 years old or older who received a diagnosis of stage I, II, or IIIA non-small-cell lung cancer between 1985 and 1996, resided in 1 of the 10 study areas covered by the Surveillance, Epidemiology, and End Results Program, and underwent surgery at a hospital that participates in the Nationwide Inpatient Sample (2118 patients and 76 hospitals). RESULTS: The volume of procedures at the hospital was positively associated with the survival of patients (P<0.001). Five years after surgery, 44 percent of patients who underwent operations at the hospitals with the highest volume were alive, as compared with 33 percent of those who underwent operations at the hospitals with the lowest volume. Patients at the highest-volume hospitals also had lower rates of postoperative complications (20 percent vs. 44 percent) and lower 30-day mortality (3 percent vs. 6 percent) than those at the lowest-volume hospitals. CONCLUSIONS: Patients who undergo resection for lung cancer at hospitals that perform large numbers of such procedures are likely to survive longer than patients who have such surgery at hospitals with a low volume of lung-resection procedures.

Aged↗
PubMed2001

Age and adjuvant chemotherapy use after surgery for stage III colon cancer.

BACKGROUND: Randomized trials have established that 5-fluorouracil-based adjuvant chemotherapy following resection of stage III colon cancer reduces subsequent mortality by as much as 30%. However, the extent to which adjuvant therapy is used outside the clinical trial setting, particularly among the elderly, is unknown. METHODS: A retrospective cohort study utilizing the Surveillance, Epidemiology, and End Results/Medicare-linked database identified 6262 patients aged 65 years and older with resected stage III colon cancer. The primary outcome was chemotherapy use within 3 months of surgery, as ascertained from Medicare claims. We examined the extent to which age at diagnosis was associated with adjuvant chemotherapy usage, and we adjusted for potential confounding based on differences in other patient characteristics with the use of multiple logistic regression. All P values were two-sided. RESULTS: Age at diagnosis was the strongest determinant of chemotherapy: 78% of patients aged 65-69 years, 74% of those aged 70-74 years, 58% of those aged 75-79 years, 34% of those aged 80-84 years, and 11% of those aged 85-89 years received postoperative chemotherapy. The age trend remained pronounced after adjustment for potential confounding based on variation in patients' demographic and clinical characteristics and after exclusion of patients with any evident comorbidity (all P values <.001). CONCLUSIONS: Adjuvant chemotherapy for stage III colon cancer is used extensively, especially for patients under the age of 75 years. However, treatment rates decline dramatically with chronologic age. Because patients in their 70s and even 80s have a reasonable life expectancy, further efforts are needed to ensure that elderly patients have the opportunity to make informed decisions regarding this potentially curative treatment.

Age Distribution↗
PubMed2001

Management of acute exacerbations of chronic obstructive pulmonary disease: a summary and appraisal of published evidence.

PURPOSE: To review critically the available data on diagnostic evaluation, risk stratification, and therapeutic management of patients with acute exacerbations of chronic obstructive pulmonary disease (COPD). DATA SOURCES: English-language articles were identified by searching MEDLINE (1966 to 2000, week 5), EMBASE (1974 to 2000, week 18), HealthStar (1975 to June 2000), and the Cochrane Controlled Trials Register (2000, Issue 1). STUDY SELECTION: The best available evidence on each subtopic was selected for analysis. Randomized trials, sometimes buttressed by cohort studies, were used to evaluate therapeutic interventions. Cohort studies were used to evaluate diagnostic tests and risk stratification. DATA EXTRACTION: Study design and results were summarized in evidence tables. Individual studies were rated by internal validity, external validity, and quality of design. Statistical analyses of combined data were not performed. DATA SYNTHESIS: Data on the utility of most diagnostic tests are limited. However, chest radiography and arterial blood gas sampling seem useful while acute spirometry does not. Identifiable clinical variables are associated with risk for relapse and risk for death after hospitalization for an acute exacerbation. Evidence of efficacy was found for bronchodilators, corticosteroids, and noninvasive positive-pressure ventilation. There is also support for the use of antibiotics in patients with more severe exacerbations. On the basis of limited data, mucolytics and chest physiotherapy do not seem to be of benefit, and oxygen supplementation seems to increase the risk for respiratory failure only in an identifiable subgroup of patients. CONCLUSIONS: Although suggestions for appropriate management can be made on the basis of available evidence, the supporting literature is scarce and further high-quality research is necessary. Such research will require an improved, generally acceptable, and transportable definition of acute exacerbation of COPD, as well as improved methods for observing and measuring outcomes.

Acute Disease↗
PubMed2001

Management of acute exacerbations of COPD: a summary and appraisal of published evidence.

STUDY OBJECTIVES: To critically review the available data on the diagnostic evaluation, risk stratification, and therapeutic management of patients with acute exacerbations of COPD. DESIGN, SETTING, AND PARTICIPANTS: English-language articles were identified from the following databases: MEDLINE (from 1966 to week 5, 2000), EMBASE (from 1974 to week 18, 2000), HealthStar (from 1975 to June 2000), and the Cochrane Controlled Trials Register (2000, issue 1). The best available evidence on each subtopic then was selected for analysis. Randomized trials, sometimes buttressed by cohort studies, were used to evaluate therapeutic interventions. Cohort studies were used to evaluate diagnostic tests and risk stratification. Study design and results were summarized in evidence tables. Individual studies were rated as to their internal validity, external validity, and quality of study design. Statistical analyses of combined data were not performed. MEASUREMENT AND RESULTS: Limited data exist regarding the utility of most diagnostic tests. However, chest radiography and arterial blood gas sampling appear to be useful, while short-term spirometry measurements do not. In terms of the risk of relapse and the risk of death after hospitalization for an acute exacerbation, there are identifiable clinical variables that are associated with these outcomes. Therapies for which there is evidence of efficacy include bronchodilators, corticosteroids, and noninvasive positive-pressure ventilation. There is also support for the use of antibiotics in patients with more severe exacerbations. Based on limited data, mucolytics and chest physiotherapy do not appear to be of benefit, and oxygen supplementation appears to increase the risk of respiratory failure in an identifiable subgroup of patients. CONCLUSIONS: Although suggestions for appropriate management can be made based on available evidence, the supporting literature is spotty. Further high-quality research is needed and will require an improved, generally acceptable, and transportable definition of the syndrome "acute exacerbation of COPD" and improved methods for observing and measuring outcomes.

Acute Disease↗
PubMed2001

Predicting mortality in patients suffering from prolonged critical illness: an assessment of four severity-of-illness measures.

STUDY OBJECTIVES: Investigators have been using severity-of-illness indexes such as APACHE II (acute physiology and chronic health evaluation score II) to describe patients with prolonged critical illness. However, little is known about the utility of these indexes for this patient population. We evaluated the ability of four severity-of-illness indexes to predict mortality rates in 182 patients with prolonged critical illness. DESIGN: Retrospective inception cohort study. SETTING: A single, urban, long-term, acute-care hospital in Chicago. PATIENTS: One hundred eighty-two patients transferred from 37 acute-care hospital ICUs. MEASUREMENTS AND RESULTS: We assessed four indexes: the acute physiology and chronic health evaluation II, the simplified acute physiology score II, the mortality prediction model II, and the logistic organ dysfunction system using variables measured on admission to the long-term acute-care hospital ICU. We found that none of these indexes distinguished well between the patients who lived and the patients who died (area under ROC [receiver operating characteristics] curve < 0.70 for all), nor did they assign correct probabilities of death to individual patients (Hosmer-Lemeshow goodness-of-fit statistics, p < 0.01 for all). CONCLUSIONS: Investigators and clinicians should use caution in using severity-of-illness measures developed for acutely ill patients to describe critically ill patients admitted to long-term care units. As clinical practice and research focus more on these latter patients, development of adequately performing severity-of-illness measures appropriate to this patient population will be needed.

APACHE↗
PubMed2000

Influence of hospital procedure volume on outcomes following surgery for colon cancer.

CONTEXT: Survival following high-risk cancer surgery, such as pancreatectomy and esophagectomy, is superior at hospitals where high volumes of these procedures are performed. Conflicting evidence exists as to whether the association between hospital experience and favorable health outcomes also applies to more frequently performed operations, such as those for colon cancer. OBJECTIVE: To determine whether hospital procedure volume predicts survival following colon cancer surgery. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort study of data from the Surveillance, Epidemiology and End Results-Medicare linked database on 27 986 colon cancer patients aged 65 years and older who had surgical resection for primary adenocarcinoma diagnosed between 1991 and 1996. MAIN OUTCOME MEASURES: Thirty-day postoperative mortality and overall and cancer-specific long-term survival, by hospital procedure volume. RESULTS: We found small differences in 30-day postoperative mortality for patients treated at low- vs high-volume hospitals (3. 5% at hospitals in the top-volume quartile vs 5.5% at hospitals in the bottom-volume quartile). However, the correlation was statistically significant and persisted after adjusting for age at diagnosis, sex, race, cancer stage, comorbid illness, socioeconomic status, and acuity of hospitalization (P<.001). The association was evident for subgroups with stage I, II, and III disease. Hospital volume directly correlated with survival beyond 30 days and also was not attributable to differences in case mix (P<.001). The association between hospital volume and long-term survival was concentrated among patients with stage II and III disease (P<.001 for both). Among stage III patients, variation in use of adjuvant chemotherapy did not explain this finding. CONCLUSION: Our data suggest that hospital procedure volume predicts clinical outcomes following surgery for colon cancer, although the absolute magnitudes of these differences are modest in comparison with the variation observed for higher-risk cancer surgeries.

Adenocarcinoma↗
PubMed2000

Epidemiology of lung cancer.

Lung cancer is the leading cause of cancer mortality in the United States, and its incidence is growing throughout the world. The high morbidity and mortality of lung cancer largely results from the fact that most people are diagnosed with advanced disease, when surgical cures are no longer possible. Although many risk factors have been implicated, the most significant risk for developing lung cancer is clearly tobacco exposure. Tobacco use is currently increasing among specific population groups. It is probable that lung cancer will continue as a major medical and social problem for the foreseeable future.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Racial differences in the treatment of early-stage lung cancer.

BACKGROUND: If discovered at an early stage, non-small-cell lung cancer is potentially curable by surgical resection. However, two disparities have been noted between black patients and white patients with this disease. Blacks are less likely to receive surgical treatment than whites, and they are likely to die sooner than whites. We undertook a population-based study to estimate the disparity in the rates of surgical treatment and to evaluate the extent to which this disparity is associated with differences in overall survival. METHODS: We studied all black patients and white patients 65 years of age or older who were given a diagnosis of resectable non-small-cell lung cancer (stage I or II) between 1985 and 1993 and who resided in 1 of the 10 study areas of the Surveillance, Epidemiology, and End Results (SEER) program (10,984 patients). Data on the diagnosis, stage of disease, treatment, and demographic characteristics of the patients were obtained from the SEER data base. Information on coexisting illnesses, type of Medicare coverage, and survival was obtained from linked Medicare inpatient-discharge records. RESULTS: The rate of surgery was 12.7 percentage points lower for black patients than for white patients (64.0 percent vs. 76.7 percent, P<0.001), and the five-year survival rate was also lower for blacks (26.4 percent vs. 34.1 percent, P<0.001). However, among the patients undergoing surgery, survival was similar for the two racial groups, as it was among those who did not undergo surgery. Furthermore, analyses in which adjustments were made for factors that are predictive of either candidacy for surgery or survival did not alter the influence of race on these outcomes. CONCLUSIONS: Our analyses suggest that the lower survival rate among black patients with early-stage, non-small-cell lung cancer, as compared with white patients, is largely explained by the lower rate of surgical treatment among blacks. Efforts to increase the rate of surgical treatment for black patients appear to be a promising way of improving survival in this group.

Aged↗
PubMed1999

Identifying providers of care to individuals with human immunodeficiency virus for a mail survey using a prescription tracking database.

Unlike cancer and other illnesses for which specialists provide the majority of care for affected individuals, care of those infected with human immunodeficiency virus (HIV) is provided by generalists and many different types of specialists. To assess the utility of a prescription tracking database in identifying low experience and high-experience providers of such care regardless of specialty, we mailed a survey to 1500 physicians identified as having written prescriptions for agents used in care of HIV-infected individuals in the year before the survey. We discovered that physicians who care for patients with acquired immunodeficiency syndrome (AIDS) in the United States come from a broad range of specialties and practice in a variety of settings. Self-report of experience with AIDS care in the prior year was strongly associated with the number of HIV-related prescriptions identified in the tracking information. Response rates were consistent with those of other surveys published in medical journals. This study suggests that prescription tracking databases can be used to identify the breadth of physician/subjects who provide care for patients with HIV infection.

Databases, Factual↗
PubMed1999

Outcomes after long-term acute care. An analysis of 133 mechanically ventilated patients.

Long-term acute-care (LTAC) hospitals are facilities exempt from the Medicare prospective payment system and which provide care to patients suffering from prolonged critical illness. From August 1, 1995 to July 31, 1996, we studied the outcomes of 133 mechanically ventilated patients who were consecutively admitted to a large urban LTAC hospital from intensive care units (ICUs) of acute-care hospitals. Survival and functional status within 1 yr after the index admission were measured, and specific patient variables were used to develop a predictive model for survival at 1 yr. Of the 133 patients studied, 66 (50%) died prior to discharge. Of discharged patients, 70% had been successfully liberated from mechanical ventilation. One year after LTAC hospital admission, 103 (77%) of the patients had expired, typically after spending the majority of their days in acute care or long-term care facilities. Eleven 1-yr survivors (8%) were fully functional, whereas the remainder had significantly reduced functional status. Patients older than 74 yr, and patients older than 64 yr and not functionally independent before admission, had a 95% (confidence interval [CI]: 84% to 99%) 1-yr mortality; patients without these characteristics had a 56% (CI: 41% to 71%) 1-yr mortality (p < 0.001). We demonstrate characteristics predicting the poorest prognoses for patients requiring prolonged mechanical ventilation. These characteristics may be identifiable before transfer to an LTAC hospital.

Adult↗
PubMed1999

The relation between physician experience and patterns of care for patients with AIDS-related Pneumocystis carinii pneumonia: results from a survey of 1,500 physicians in the United States.

STUDY OBJECTIVES: To determine whether physician experience and specialty influence the approach to care of AIDS patients with pneumonia, we surveyed physicians about their management of possible Pneumocystis carinii pneumonia (PCP) infection. DESIGN, SETTING, PARTICIPANTS: A postal survey was sent to a random sample of 1,500 internists and family physicians in the United States drawn from the American Medical Association master file who were identified by a pharmaceutical marketing company as having written prescriptions for AIDS-related agents in the previous year. MEASUREMENTS AND RESULTS: The survey had a 53% response rate. Physicians more experienced in AIDS care were more likely to advocate diagnostic bronchoscopy over initiation of empiric anti-PCP therapy for HIV-infected patients with undiagnosed pulmonary infiltrates (odds ratio [OR], 1.4 for a patient with mild severity of illness [p = 0.02]; OR, 1.7 for a severely ill patient [p < 0.001]). Physician specialty and fee-for-service reimbursement were independently associated with higher rates of bronchoscopy, with internists favoring bronchoscopy more frequently than family physicians. High-experience providers and internists also predicted better clinical outcomes for the hypothetical patients. CONCLUSIONS: Our findings extend the observations about HIV experience and PCP prophylaxis to the setting of diagnosis and treatment. Physicians with higher levels of experience with AIDS, internists, and physicians reimbursed as fee-for-service providers are more likely to support diagnostic confirmation of PCP than empiric treatment approaches.

AIDS-Related Opportunistic Infections↗
PubMed1999

Methadone dosing, heroin affordability, and the severity of addiction.

OBJECTIVES: This study sought to track changes in US heroin prices from 1988 to 1995 and to determine whether changes in the affordability of heroin were associated with changes in the use of heroin by users seeking methadone treatment, as indexed by methadone dose levels. METHODS: Data on the price of heroin were from the Drug Enforcement Administration; data on methadone doses were from surveys conducted in 1988, 1990, and 1995 of 100 methadone maintenance centers. Multivariable models that controlled for time and city effects were used to ascertain whether clinics in cities where heroin was less expensive had patients receiving higher doses of methadone, which would suggest that these patients had relatively higher physiological levels of opiate addiction owing to increased heroin use. RESULTS: The amount of pure heroin contained in a $100 (US) purchase has increased on average 3-fold between 1988 and 1995. The average dose of methadone in clinics was positively associated with the affordability of local heroin (P < .01). CONCLUSIONS: When heroin prices fall, heroin addicts require more methadone (a heroin substitute) to stabilize their addiction--evidence that they are consuming more heroin.

Health Surveys↗
PubMed1998

Outcomes and resource utilization for patients with prolonged critical illness managed by university-based or community-based subspecialists.

We studied 118 patients with prolonged critical illness to determine if there would be a difference in outcome between patients managed by university-based (UB) or community-based (CB) intensivists. Patients consecutively admitted to a long-term acute care hospital were assigned in an arbitrary manner to the UB service or CB service. Patient survival, length of stay, and success and length of time required for liberation from mechanical ventilation (MV) were compared using survival analysis, logistic regression, and analysis of variance techniques. Patients on the UB service were liberated from MV in 32% fewer days (39 versus 57 d, p = 0.02) and were marginally more likely to be liberated from MV (46% versus 30%, p = 0.14). UB physicians were more likely to write do not resuscitate orders (59% versus 33%, p < 0.01) and to withdraw life-sustaining therapy (12% versus 2%, p = 0.09). There were no detectable differences in survival between the two groups. Estimated reimbursement for CB physicians ($6,797/patient) was 46% greater than for UB physicians ($4,651/patient) for discharged patients (p = 0.03). We conclude that patients experiencing prolonged critical illness may experience different outcomes based on their physician provider. In our study, patients were liberated more quickly from MV, were withdrawn from life support more readily, and were managed at lower cost by UB intensivists than by CB intensivists.

Academic Medical Centers↗