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Biomedical subjects

J L Warren

Publications and source records attributed to J L Warren.

At least 19 recordsLinked to original sources
PubMed2001

Bowel surveillance patterns after a diagnosis of colorectal cancer in Medicare beneficiaries.

BACKGROUND: Postoperative colon surveillance has been recommended for patients with a diagnosis of local/regional colorectal cancer. The extent to which these recommendations are followed in practice is poorly characterized. Patterns of surveillance after surgery for colorectal cancer were determined by using a large population-based database. METHODS: This is a retrospective cohort study with cancer registry data linked to Medicare claims. Identified were 52,283 patients treated for local/regional colorectal cancer between 1986 and 1996, and surveillance patterns through 1998 were determined. Surveillance patterns were analyzed by using survival analysis and by computing the proportion of surviving patients who underwent procedures during 4 time periods after treatment: 2 to 14 months, 15 to 50 months, 51 to 86 months and more than 87 months. RESULTS: Median times to first through fifth surveillance events were 20, 14, 15, 15, and 15 months, respectively. For 17% of the cohort there was no surveillance event. Younger patients were more likely to undergo surveillance. Surveillance patterns were not affected by stage. The proportions of the cohort that underwent no surveillance during the 4 respective time periods were 54%, 52%, 60%, and 69%. The percentages of patients who underwent surveillance annually or more frequently in the latter 3 time periods, respectively, were 19%, 10%, and 5%, or 11% overall, treating the data for the 3 events as a whole. Over the period from 1986 to 1998, the proportion of patients who had no surveillance procedures gradually decreased, whereas the proportion of those who underwent procedures annually or more frequently remained relatively constant. CONCLUSIONS: During the period from 1986 to 1998 there was low utilization of postdiagnosis colon surveillance in a substantial proportion of elderly patients with a diagnosis of local/regional colorectal cancer. Over time there was a trend toward increasing receipt of any surveillance procedures. The percentages of patients undergoing surveillance annually or more frequently did not change between earlier and later periods.

Aged↗
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

Development of a comorbidity index using physician claims data.

Important comorbidities recorded on outpatient claims in administrative datasets may be missed in analyses when only inpatient care is considered. Using the comorbid conditions identified by Charlson and colleagues, we developed a comorbidity index that incorporates the diagnostic and procedure data contained in Medicare physician (Part B) claims. In the national cohorts of elderly prostate (n = 28,868) and breast cancer (n = 14,943) patients assessed in this study, less than 10% of patients had comorbid conditions identified when only Medicare hospital (Part A) claims were examined. By incorporating physician claims, the proportion of patients with comorbid conditions increased to 25%. The new physician claims comorbidity index significantly contributes to models of 2-year noncancer mortality and treatment received in both patient cohorts. We demonstrate the utility of a disease-specific index using an alternative method of construction employing study-specific weights. The physician claims index can be used in conjunction with a comorbidity index derived from inpatient hospital claims, or employed as a stand-alone measure.

Breast Neoplasms↗
PubMed2000

Is there cross-format transfer in implicit invariance learning?

Three experiments investigated cross-form transfer in the invariance learning paradigm introduced by McGeorge and Burton (1990). The results suggest that the transfer observed by McGeorge and Burton depended on subjects' ability to use a response strategy discovered by Wright and Burton (1995). When that strategy was denied to subjects (Experiments 1 and 2), no cross-form transfer was observed; when the strategy was made available (Experiment 3), cross-form transfer re-emerged. These results suggest that this form of learning, like many other forms of implicit learning and memory, is hyperspecific.

Adult↗
PubMed2000

Accuracy and completeness of Medicare claims data for surgical treatment of breast cancer.

BACKGROUND: Although a number of studies have used Medicare claims data to study trends and variations in breast cancer treatment, the accuracy and completeness of information on surgical treatment for breast cancer in the Medicare data have not been validated. OBJECTIVES: This study assessed the accuracy and completeness of Medicare claims data for breast cancer surgery to determine whether Medicare claims can serve as a source of data to augment information collected by cancer registries. METHODS: We used the Surveillance, Epidemiology and End Results (SEER) Cancer Registry-Medicare data and compared Medicare claims on surgery with the surgery recorded by the SEER registries for 23,709 women diagnosed with breast cancer at > or =65 years of age from 1991 through 1993. RESULTS: More than 95% of women having mastectomies according to the Medicare data were confirmed by SEER. For breast-conserving surgery, 91% of cases were confirmed by SEER. The Medicare physician services claims and inpatient claims were approximately equal in accuracy on type of surgery. The Medicare outpatient claims were less accurate for breast-conserving surgery. In terms of completeness, when the 3 claims sources were combined, 94% of patients receiving breast cancer surgery according to SEER were identified by Medicare. CONCLUSIONS: The combined Medicare claims database, which includes the inpatient, outpatient, and physician service claims, provides valid information on surgical treatment among women known to have breast cancer. The claims are a rich source of data to augment the information collected by tumor registries and provide information that can be used to follow long-term outcomes of Medicare beneficiaries.

Breast Neoplasms↗
PubMed1999

Role of transurethral resection of the prostate in population-based prostate cancer incidence rates.

The extensive pool of asymptomatic prostate disease in the population, which increases substantially with age, suggests that the frequent use of transurethral resection of the prostate (TURP) in recent decades has had a large effect on prostate cancer incidence. The authors identified the effect of TURP-detected prostate cancer on the observed incidence rates between 1973 and 1993 for men aged 65 years and older. They linked population-based cancer registry data from the Surveillance, Epidemiology, and End Results Program to Medicare records between 1986 and 1993 to determine whether a TURP occurred sufficiently close to the time of a prostate cancer diagnosis for them to assume that it led to the diagnosis. TURP-detected cases prior to 1986 were calculated using an indirect method that involved multiplying the TURP procedure rate in the general population (from the National Hospital Discharge Survey) by estimates of the proportion of TURPs resulting in a prostate cancer diagnosis (from Medicare data and the literature). TURP explained much of the observed increase in overall prostate cancer incidence between 1973 and 1986 and possibly all of it in men aged 70 years and older. However, its influence on the trend and overall magnitude of the rates diminished between 1987 and 1993. The changing role of TURP in detecting prostate cancer is attributed to changes in medical technology and screening practices. The declining influence of TURP on prostate cancer incidence is likely to have continued beyond the study period due to the recent introduction and increasing use of medications for treating obstructive uropathy.

Aged↗
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

Cancer surveillance series [corrected]: brain and other central nervous system cancers: recent trends in incidence and mortality.

BACKGROUND: During the 1980s, the incidence of primary malignant brain and other central nervous system tumors (hereafter called brain cancer) was reported to be increasing among all age groups in the United States, while mortality was declining for persons younger than 65 years. We analyzed these data to provide updates on incidence and mortality trends for brain cancer in the United States and to examine these patterns in search of their causes. METHODS: Data on incidence, overall and according to histology and anatomic site, and on relative survival were obtained from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute for 1975 through 1995. Mortality data were obtained from the National Center for Health Statistics. Medicare procedure claims from the National Cancer Institute's SEER-Medicare database were used for imaging trends. Statistically significant changes in incidence trends were identified, and annual percent changes were computed for log linear models. RESULTS/CONCLUSIONS: Rates stabilized for all age groups during the most recent period for which SEER data were available, except for the group containing individuals 85 years of age or older. Mortality trends continued to decline for the younger age groups, and the steep increases in mortality seen in the past for the elderly slowed substantially. Patterns differed by age group according to the site and grade of tumors between younger and older patients. During the last decade, use of computed tomography scans was relatively stable for those 65-74 years old but increased among those 85 years old or older. IMPLICATIONS: Improvements in diagnosis and changes in the diagnosis and treatment of elderly patients provide likely explanations for the observed patterns in brain cancer trends.

Adolescent↗
PubMed1999

Rising incidence of renal cell cancer in the United States.

CONTEXT: Clinical surveys have revealed that incidental detection of renal cell carcinoma is rising because of increased use of imaging procedures. OBJECTIVE: To examine incidence, mortality, and survival trends of renal cell and renal pelvis cancers by age, sex, race, and tumor stage at diagnosis. DESIGN: Calculation of age-adjusted incidence and mortality rates, along with 5-year relative survival rates, using data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program. SETTING AND PARTICIPANTS: Patients diagnosed as having kidney cancer from 1975 through 1995 in the 9 geographic areas covered by tumor registries in the SEER program, which represent about 10% of the US population. MAIN OUTCOME MEASURES: Incidence, mortality, and 5-year relative survival rates by time periods. RESULTS: The age-adjusted incidence rates for renal cell carcinoma between 1975 and 1995 for white men, white women, black men, and black women were 9.6, 4.4, 11.1, and 4.9 per 100000 person-years, respectively. The corresponding rates for renal pelvis cancer were 1.5, 0.7, 0.8, and 0.5 per 100000 person-years. Renal cell cancer incidence rates increased steadily between 1975 and 1995, by 2.3% annually among white men, 3.1 % among white women, 3.9% among black men, and 4.3% among black women. Increases were greatest for localized tumors but were also seen for more advanced and unstaged tumors. In contrast, the incidence rates for renal pelvis cancer declined among white men and remained stable among white women and blacks. Although 5-year relative survival rates for patients with renal cell cancer improved among whites but not among blacks, kidney cancer mortality rates increased in all race and sex groups. CONCLUSIONS: Increasing detection of presymptomatic tumors by imaging procedures, such as ultrasonography, computed tomography, and magnetic resonance imaging, does not fully explain the upward incidence trends of renal cell carcinoma. Other factors may be contributing to the rapidly increasing incidence of renal cell cancer in the United States, particularly among blacks.

Adolescent↗
PubMed1999

Stage at diagnosis and treatment patterns among older women with breast cancer: an HMO and fee-for-service comparison.

CONTEXT: Few studies have compared patterns of care in health maintenance organization (HMO) and fee-for-service (FFS) settings. OBJECTIVE: To examine breast cancer stage at diagnosis and, for those at an early stage, treatment patterns for elderly women in HMO and FFS settings. DESIGN: Cancer registry data from the Surveillance, Epidemiology, and End Results (SEER) program linked to Medicare enrollment records. SETTINGS AND PARTICIPANTS: Women aged 65 years or older residing in 11 geographic areas who were newly diagnosed as having breast cancer between 1988 and 1993. MAIN OUTCOME MEASURES: Standardized percentage of cases diagnosed at late stages for HMO vs FFS; standardized percentage of early-stage cases undergoing initial treatment with breast-conserving surgery (BCS); and, among BCS cases, standardized percentage receiving adjuvant radiation therapy. Standardization was achieved through logistic regression, controlling for patient demographics, cancer history, county of residence, year of diagnosis, and educational attainment at the census tract level. Analyses of treatment patterns were controlled for stage at diagnosis and tumor size. RESULTS: The HMO enrollees were less likely to have breast cancer diagnosed at late stages than FFS patients (HMO, 7.6%; FFS, 10.8%; difference, -3.2% [95% confidence interval (CI), -4.2% to -2.2 %]). Among early-stage cases, the percentages undergoing BCS were similar in HMO and FFS settings overall (HMO, 38.4%; FFS, 36.8%; difference, 1.6% [95% CI, 0.0%-3.2%]); percentages varied markedly at the individual plan level. Among women undergoing BCS, HMO enrollees were significantly more likely to receive radiation therapy but, again, results varied by plan (HMO, 69.0%; FFS, 63.7%; difference, 5.3% [95% CI, 2.9%-7.7%]). In general, use of BCS and radiation therapy was substantially higher than that found in an earlier study examining cases diagnosed between 1985 and 1989. CONCLUSIONS: Treatment of early-stage breast cancer in HMOs often differs from local FFS patterns, but not in a consistent way. During the period of our study, elderly HMO enrollees did not appear to have systematic access problems with adjuvant radiation therapy following BCS compared with women in an FFS setting.

Aged↗
PubMed1999

Use of Medicare hospital and physician data to assess breast cancer incidence.

OBJECTIVES: Health claims data have the potential of being an inexpensive, timely, and nationally representative source of information about cancer. This study examined the utility of Medicare hospital and physician data as an independent source to identify incident breast cancer cases. METHODS: Data came from Medicare and the National Cancer Institute's SEER cancer registries. From 1992, for women residing in the SEER states (n = 659,260), Medicare hospital and physician claims were reviewed to identify women with a breast cancer diagnosis on a claim (n = 6,784). These women were matched with women in the SEER data who had been diagnosed with breast cancer in 1992 (n = 3,230). The sensitivity, specificity, and positive predictive value (PPV) of the Medicare data were calculated. Logistic regression models were used to identified cancer related procedures reported to Medicare that could distinguish true cases from false positive cases. Predicted values from these models were included to create plots of sensitivity versus false positive rates and sensitivity versus PPV. RESULTS: Medicare hospital data had 62% sensitivity, 99.9% specificity, and 88% PPV. Physician claims increased sensitivity by 14%, with specificity of 99.4%, and a PPV of 10%. Inclusion of additional cancer related diagnoses and procedures improved the ability to distinguish true cases from false positives, although the number of false positive cases remained high. CONCLUSIONS: The Medicare data overall offer limited potential to assess breast cancer incidence, largely because of low sensitivity and poor PPV. The Medicare data may have utility to identify women undergoing selected breast cancer treatments. In addition, the data may be used to help registries focus case-finding efforts, particularly for persons undergoing cancer related treatments.

Breast Neoplasms↗
PubMed1998

Trends and outcomes of outpatient mastectomy in elderly women.

BACKGROUND: Considerable public attention has focused on the use of outpatient mastectomy and has resulted in numerous legislative proposals to mandate a minimum hospital stay following mastectomy. To date, only limited scientific data are available regarding the use and the outcomes of outpatient mastectomy. The purpose of this study was to provide population-based information on trends and outcomes for outpatient mastectomy in elderly women. METHODS: Medicare data for elderly women with fee-for-service coverage were examined for trends and regional variation in the use of outpatient mastectomy. Logistic regression was used to identify patient and provider characteristics associated with having an outpatient mastectomy, and outcomes were assessed by calculating the risk of being rehospitalized and the reasons for rehospitalization. RESULTS: From 1986 through 1995, the proportion of mastectomies performed on an outpatient basis increased from virtually 0% to 10.8%. Outpatient mastectomies were more likely to be performed on women with no coexisting health problems in hospitals that were for-profit or non-teaching or in large metropolitan statistical areas. Women undergoing outpatient mastectomy had substantially higher rates of rehospitalization within 30 days than women with a 1-day stay in the hospital. Both groups had comparable rates of rehospitalization for complications definitely related to their surgery. The percentage of women who required rehospitalization was low, and the actual number of women rehospitalized was relatively small. CONCLUSIONS: We conclude that the risks from outpatient mastectomy are modest, although ongoing monitoring of outcomes and assessment of patient satisfaction are needed.

Aged↗
PubMed1998

Early views of the martian surface from the Mars Orbiter Camera of Mars Global Surveyor.

High-resolution images of the martian surface at scales of a few meters show ubiquitous erosional and depositional eolian landforms. Dunes, sandsheets, and drifts are prevalent and exhibit a range of morphology, composition (inferred from albedo), and age (as seen in occurrences of different dune orientations at the same location). Steep walls of topographic depressions such as canyons, valleys, and impact craters show the martian crust to be stratified at scales of a few tens of meters. The south polar layered terrain and superposed permanent ice cap display diverse surface textures that may reflect the complex interplay of volatile and non-volatile components. Low resolution regional views of the planet provide synoptic observations of polar cap retreat, condensate clouds, and the lifecycle of local and regional dust storms.

Carbon Dioxide↗
PubMed1997

Medicare Part A utilization and expenditures for psychiatric services: 1995.

This study provides an overview of Medicare's current coverage and payment policies regarding hospitalization for psychiatric disorders, and presents new information on demographic, diagnostic, utilization, and expenditure characteristics associated with inpatient psychiatric care among 1995 Medicare beneficiaries. Results suggest that utilization and expenditure patterns for Medicare beneficiaries hospitalized for psychiatric illness in 1995 differ across demographic (e.g., age, sex, race) and diagnostic categories. The implications of these findings for current management of the Medicare program as well as the evolution of Medicare managed care systems for behavioral health services are discussed.

Demography↗
PubMed1996

Use of Medicare data to identify incident breast cancer cases.

Surveillance, Epidemiology and End Results (SEER) data from the National Cancer Institute (NCI) provide reliable information about cancer incidence. However, because SEER data are geographically limited and have a 2-year time lag, we evaluated whether Medicare data could provide timely information on cancer incidence. Comparing Medicare women hospitalized for breast cancer with women reported to SEER, Medicare data had high specificity (96.6 percent), yet low sensitivity (59.4 percent). We conclude that Medicare hospitalization data can identify incident cases for cancers that usually require inpatient hospitalization. For cancers that often only receive outpatient treatment, such as breast cancer, additional Medicare data, such as physician bills, are needed to understand the entirety of treatment practices.

Aged↗