Kwan-Moon Leung

Patients with newly diagnosed carcinoma of the breast: validation of a claim-based identification algorithm.

The objectives of this study were to validate a claims-based algorithm for identification of patients with newly diagnosed carcinoma of the breast and to optimize the algorithm. Claims data from all females aged 21 years or older who enrolled in a large California health maintenance organization during the study period from October 1, 1994 through March 31, 1996 were analyzed. Medical records of the patients identified through the claims-based algorithm were reviewed to determine whether the patients were correctly identified. The initial algorithm had a positive predictive value of 84% which was similar to the previous study. The percentages of correct identification significantly increased with the patients age at diagnosis. Other patient demographic characteristics and facility characteristics were not related to the accuracy of the identification. Using a classification tree procedure and additional information from the false-positive cases, the initial algorithm was modified for improvement. The best-modified algorithm had a positive predictive value of 92% while only 0.5% (4/837) of the true-positive cases were excluded. The results once again demonstrated that patients with newly diagnosed carcinomas of the breast can be identified using claims data. These databases provide an efficient and effective tool for performing health services studies on large patient populations.

Axillary node dissection in Ductal carcinoma in situ

Intraductal carcinoma of the breast has become a well-defined entity that has been more frequently diagnosed since the introduction of mammography. For many years, the usual treatment has been mastectomy, often with axillary lymph node dissection. Concurrent with documentation that breast conservation treatment has been effective for many invasive breast cancers, such treatment has been introduced for noninvasive breast cancers (ductal carcinoma in situ and lobular cancer in situ). However, there is no basis for axillary dissection because tumor cells are contained by the basement membrane and should not metastasize. In this study, 107 axillary dissections were carried out, with an average of 20 nodes identified, and a single metastasis was identified.

Mammographic Screening Downstages Breast Carcinomas at Time of Diagnosis: A Community-Based Experience

Abstract: To determine the effectiveness of screening mammography in a community medical setting, data from a population‐based, retrospective study was analyzed. Medical records of 827 patients with newly diagnosed breast cancer in California between October 1994 and March 1996 were reviewed. The primary care physicians record was abstracted for clinical history, including recommendation of screening mammography. The facility records where final diagnosis was made were abstracted for stage and treatment data. Among the patients who did not have previous screening mammography, 65.7% were diagnosed with “advanced” breast cancer (stages II, III, IV), while only 39.9% who had previous screening mammography were diagnosed with advanced breast cancer (p < 0.001). This study has reaffirmed that screening mammography of adult females generates downstaging at the time of diagnosis of breast cancer. Despite possession of a health insurance program and receiving educational materials, only 65% of patients over 50 years of age had screening mammography. As opposed to the once‐a‐year mailing of general reminders to all women 40 years old and older, developing a longitudinal electronic medical record in the managed care setting will support a more coordinated and individualized intervention based on age, date of last mammogram, and relative risk, among other factors. Continuing education efforts must also be directed to referring physicians, who may not yet recognize the value of screening mammography.

Expression of risk factors for breast cancer in women younger than 49.

The definition of women younger than 49 who are at increased risk for breast cancer would enable intensified efforts in surveillance and use of preventive measures for this group. In this survey of 32,123 members of Health Net, an increased risk for breast cancer was related to age, breast cancer in the immediate family (mother, sister), and previous biopsies for cystic lesions of the breast. No increased risk was related to menarche, nulliparity, first pregnancy after age 30, or breast feeding.

Validity of clinical information from a maternity survey.

This research was designed to validate data collected through a survey—an inexpensive way to provide information for quality measurement. The survey was sent to health maintenance organization (HMO) enrollees who had given birth(s) between October 1, 1994, and May 31, 1995. The responses were compared with the medical records. A sample of 407 women was randomly selected from the completed surveys. Medical records were reviewed for 89.9% (362/407) of the sample based on medical record availability. Over 98% of responses agreed with the medical record information regarding whether there were cesarean sections for previous deliveries (K = 1.0), cesarean section for recent delivery (κ = 0.95), and vaginal birth after cesarean section (κ = 0.96). Over 99% of the mothers agreed with the information regarding whether the newborn birth weight was under 2500 g (κ = 0.91). The findings strongly support the validation of this instrument. Using this validated instrument enables health plans to cost-effectively obtain crucial information.

Combining Information from Multiple Sources in the Analysis of a Non-Equivalent Control Group Design

In studies of whether hospital or health-center interventions can improve screening rates for mammography and Pap smears in Los Angeles County, the availability of data from multiple sources makes it possible to combine information in an effort to improve the estimation of intervention effects. Primary sources of information, namely computerized databases that record screening outcomes and some covariates on a routine basis, are supplemented by medical chart reviews that provide additional, sometimes conflicting, assessments of screening outcomes along with additional covariates. Available data can be classified in a large contingency table where, because medical charts were not reviewed for all individuals, some cases can only be classified into a certain margin as opposed to a specific cell. This paper outlines a multiple imputation approach to facilitate data analysis using the framework of Schafer (1991, 1995), which involves drawing imputations from a multinomial distribution with cell probabilities estimated from a loglinear model fitted to the incomplete contingency table. Because of the sparseness of the contingency table, a cavalier choice of a convenient prior distribution can be problematic. The completed data are then analyzed using the method of propensity score sub classification (Rosenbaum and Rubin 1984) to reflect differences in the patient populations at different hospitals or health centers.