Biomedical subjects

Daniel F Heitjan

Publications and source records attributed to Daniel F Heitjan.

24 records · Page 2Linked to original sources

PubMed2002

Use of adjuvant chemotherapy and radiation therapy for rectal cancer among the elderly: a population-based study.

PURPOSE: Combined adjuvant fluorouracil (5-FU)-based chemotherapy with radiation is now the standard of care for locally advanced rectal cancer in the United States. We investigated the use of these treatments for stages II and III rectal cancer among the elderly and the effectiveness of these treatments on a population-based scale. PATIENTS AND METHODS: The linked Surveillance, Epidemiology, and End-Results-Medicare database was used to identify 1,807 Medicare beneficiaries > or = 65 years of age with stage II or III rectal cancer who underwent surgical resection between 1992 and 1996. We excluded members of a health maintenance organization in the 12 months before or 4 months after their diagnosis and those who died within 4 months of diagnosis. We used multivariate analysis to identify factors associated with combined 5-FU and radiation therapy, and propensity score methodology to determine survival benefit for those treated. RESULTS: We found that 37% of patients received both adjuvant 5-FU and radiation therapy, 11% 5-FU alone, and 14% radiation alone. Decreasing age, increasing lymph node positivity, comorbid conditions, and nonblack race were associated with increased probability of treatment with 5-FU and radiation. Combined chemotherapy/radiation therapy was associated with improved survival for stage III (relative risk, 0.71; 95% confidence interval, 0.56 to 0.90), but not for stage II rectal cancer (relative risk, 0.89; 95% confidence interval, 0.70 to 1.14). CONCLUSION: The association of combined treatment with improved survival in node-positive disease was similar to that observed in other studies. In the absence of data from well-designed randomized controlled trials, our observational data support efforts on the part of clinicians to make appropriate referrals and provide combined treatment for elderly patients with stage III rectal cancer.

Age Factors↗

PubMed2002

Effect of prevention strategies on survival and quality-adjusted survival of women with BRCA1/2 mutations: an updated decision analysis.

PURPOSE: This study updates findings regarding the effects of prophylactic surgery, chemoprevention, and surveillance on the survival and quality-adjusted survival of women who test positive for BRCA1/2 mutations. MATERIALS AND METHODS: Markov modeling of outcomes was performed in a simulated cohort of 30-year-old women who tested positive for BRCA1/2 mutations. The model incorporated breast and ovarian cancer incidence rates from the literature and mortality rates from the Surveillance, Epidemiology, and End Results Program. Quality adjustment of survival estimates were obtained from a survey of women aged 33 to 50 years. Sensitivity analyses were performed of varied assumptions regarding timing and effects of preventive measures on cancer incidence and adverse effects. RESULTS: A 30-year-old woman could prolong her survival beyond that associated with surveillance alone by use of preventive measures: 1.8 years with tamoxifen, 2.6 years with prophylactic oophorectomy, 4.6 years with both tamoxifen and prophylactic oophorectomy, 3.5 years with prophylactic mastectomy, and 4.9 years with both surgeries. She could prolong her quality-adjusted survival by 2.8 years with tamoxifen, 4.4 years with prophylactic oophorectomy, 6.3 years with tamoxifen and oophorectomy, and 2.6 years with mastectomy, or with both surgeries. The benefits of all of these strategies would decrease if they were initiated at later ages. CONCLUSION: Women who test positive for BRCA1/2 mutations may derive greater survival and quality adjusted survival benefits than previously reported from chemoprevention, prophylactic surgery, or a combination. Observational studies and clinical trials are needed to verify the results of this analysis of the long-term benefits of preventive strategies among BRCA1/2-positive women.

Adult↗

PubMed2002

Survival associated with 5-fluorouracil-based adjuvant chemotherapy among elderly patients with node-positive colon cancer.

BACKGROUND: Randomized clinical trials have demonstrated the efficacy of adjuvant 5-fluorouracil (5-FU)-based chemotherapy after surgical resection of node-positive colon cancer. Although this treatment became the standard in 1990 following a National Institutes of Health Consensus Conference, among those at least 65 years of age it is less likely to be offered to older or nonwhite patients. OBJECTIVE: To determine the association between 5-fu-based chemotherapy and survival in older patients. DESIGN: Retrospective cohort study. SETTING: Combined database of the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program and Medicare. PATIENTS: 4768 patients 65 years of age or older who received a diagnosis of node-positive colon cancer from 1992 to 1996, were covered by Medicare Parts A and B, and resided in the population covered by the SEER program. MEASUREMENTS: Propensity scores to control for known predictors of receiving treatment, Cox proportional hazards models to assess the association of 5-FU therapy with survival, and sensitivity analyses to estimate the possible effects of unknown confounders. RESULTS: Fifty-two percent of patients received 5-FU therapy. For this sample, the hazard ratio for death associated with 5-FU therapy was 0.66 (95% CI, 0.60 to 0.73). Confounding could have accounted for this association only if an unmeasured confounder were extremely unequally distributed between the treated and untreated groups or increased mortality by at least 50%. CONCLUSIONS: 5-Fluorouracil adjuvant therapy is significantly associated with reduced mortality in older patients, similar to the association found in randomized, controlled trials among younger patients. More frequent use of 5-FU therapy in older patients would probably reduce death from colon cancer.

Age Factors↗

PubMed2002

Outcomes of tamoxifen chemoprevention for breast cancer in very high-risk women: a cost-effectiveness analysis.

PURPOSE: To estimate the effects on survival, quality-adjusted survival, and health care costs of using tamoxifen for primary prevention in subgroups of women at very high risk for breast cancer. PATIENTS AND METHODS: A decision analysis was performed using a hypothetical cohort of women that included subgroups with atypical hyperplasia, Gail risk greater than 5, lobular carcinoma-in-situ, or two or more first-degree relatives with breast cancer. Data sources were the Breast Cancer Prevention Trial, the Surveillance, Epidemiology, and End-Results program, time trade-off preference ratings, the Group Health Cooperative of Puget Sound, and the United States Health Care Financing Administration. RESULTS: Our model predicted that tamoxifen would prolong the average survival of cohort members initiating use at ages 35, 50, and 60 years by 70, 42, and 27 days, respectively. It would prolong survival even more for those in the higher-risk groups, especially those with atypical hyperplasia (202, 89, and 45 days). Tamoxifen use was also projected to extend quality-adjusted survival by 158, 80, and 50 days in the atypical hyperplasia group. For younger women in the highest risk groups, chemoprevention with tamoxifen was estimated to have cost savings or be cost-effective, both with and without quality adjustments. CONCLUSION: Chemoprevention with tamoxifen may be particularly beneficial to women with atypical hyperplasia, 5-year Gail model risk greater than 5%, lobular carcinoma-in-situ, or two or more first-degree relatives with breast cancer. The benefits may be greater if tamoxifen is initiated before age 50 years rather than after and if the breast cancer risk reduction conferred by tamoxifen lasts longer than 5 years. For women with a very high risk of invasive breast cancer, chemoprevention with tamoxifen seems to be cost-effective.

Adult↗

PubMed2002

Measuring agreement in medical informatics reliability studies.

Agreement measures are used frequently in reliability studies that involve categorical data. Simple measures like observed agreement and specific agreement can reveal a good deal about the sample. Chance-corrected agreement in the form of the kappa statistic is used frequently based on its correspondence to an intraclass correlation coefficient and the ease of calculating it, but its magnitude depends on the tasks and categories in the experiment. It is helpful to separate the components of disagreement when the goal is to improve the reliability of an instrument or of the raters. Approaches based on modeling the decision making process can be helpful here, including tetrachoric correlation, polychoric correlation, latent trait models, and latent class models. Decision making models can also be used to better understand the behavior of different agreement metrics. For example, if the observed prevalence of responses in one of two available categories is low, then there is insufficient information in the sample to judge raters' ability to discriminate cases, and kappa may underestimate the true agreement and observed agreement may overestimate it.

Decision Making↗

PubMedDate not supplied

Design and analysis of controlled trials in naturally clustered environments: implications for medical informatics.

In medical informatics research, study questions frequently involve individuals who are grouped into clusters. For example, an intervention may be aimed at a clinician (who treats a cluster of patients) with the intention of improving the health of individual patients. Correlation among individuals within a cluster can lead to incorrect estimates of the sample size required to detect an effect and inappropriate estimates of the confidence intervals and the statistical significance of the intervention effects. Contamination, which is the spread of the effect of an intervention or control treatment to the opposite group, often occurs between individuals within clusters. It leads to an attenuation of the effect of the intervention and reduced power to detect a difference. If individuals are randomized in a clinical trial (individual-randomized trial), then correlation must be taken into account in the analysis, and the sample size may need to be increased to compensate for contamination. Randomizing clusters rather than individuals (cluster-randomized trials) can eliminate contamination and may be preferred for logistical reasons. Cluster-randomized trials are generally less efficient than individual-randomized trials, so the tradeoffs must be assessed. Correlation must be taken into account in the analysis and in the sample-size calculations for cluster-randomized trials.

Cluster Analysis↗