Biomedical subjects

M Shwartz

Publications and source records attributed to M Shwartz.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Validation of a model of breast cancer screening: an outlier observation suggests the value of breast self-examinations.

As part of a validation of a mathematical model of breast cancer, the Health Insurance Plan of Greater New York (HIP) randomized controlled trial of breast cancer screening and the uncontrolled Breast Cancer Detection Demonstration Projects (BCDDP) trial were simulated. Model predictions were in accord with the nine-year survival experience of women in the HIP trial, and, with the exception of women 40-44 years old, with HIP data on 18-year survival. Five-year survival rates of screen-detected cases in the BCDDP were very close to the model's predictions. However, the model did not predict the high survival rate of women who had interval cancers in the BCDDP. By the end of the BCDDP, almost 85% of the participants performed breast self-examination (BSE) regularly. Consistent with this observation, an appealing hypothesis to explain the high survival rate of women who had interval cancers is that BSE is of value in detecting breast cancers earlier. Consideration of model outliers can be of value in increasing understanding of the phenomena being modeled.

Adult↗

PubMedDate not supplied

Predicting in-hospital mortality for stroke patients: results differ across severity-measurement methods.

OBJECTIVE: To see whether severity-adjusted predictions of likelihoods of in-hospital death for stroke patients differed among severity measures. METHODS: The study sample was 9,407 stroke patients from 94 hospitals, with 916 (9.7%) in-hospital deaths. Probability of death was calculated for each patient using logistic regression with age-sex and each of five severity measures as the independent variables: admission MedisGroups probability-of-death scores; scores based on 17 physiologic variables on admission; Disease Staging's probability-of-mortality model; the Seventy Score of Patient Management Categories (PMCs); and the All Patient-Refined Diagnosis Groups (APR-DRGs). For each patient, the odds of death predicted by the severity measures were compared. The frequencies of seven clinical indicators of poor prognosis in stroke were examined for patients with very different odds of death predicted by different severity measures. Odds ratios were considered very different when the odds of death predicted by one severity measure was less than 0.5 or greater than 2.0 of that predicted by a second measure. RESULTS: MedisGroups and the physiology scores predicted similar odds of death for 82.2% of the patients. MedisGroups and PMCs disagreed the most, with very different odds predicted for 61.6% of patients. Patients viewed as more severely III by MedisGroups and the physiology score were more likely to have the clinical stroke findings than were patients seen as sicker by the other severity measures. This suggests that MedisGroups and the physiology score are more clinically credible. CONCLUSIONS: Some pairs of severity measures ranked over 60% of patients very differently by predicted probability of death. Studies of severity-adjusted stroke outcomes may produce different results depending on which severity measure is used for risk adjustment.

Adolescent↗

PubMedDate not supplied

The ratio of costs to charges: how good a basis for estimating costs?

This study evaluates the accuracy of costs derived from the ratio of costs to charges (RCCs), using costs based on relative value units (RVUs) as the "gold standard." We found that RCC-calculated costs were not a good basis for determining the costs of individual patients. However, when examining average costs per diagnosis-related group (DRG), RCCs performed better. For almost 70% of the DRGs, average RCC-calculated costs were within 10% of average RVU-calculated costs. RCCs were even more reliable for comparing the relative cost of patients in a DRG in one hospital to the average cost of patients in that DRG in a group of hospitals. Charges, or an overall hospital RCC (as opposed to the departmental RCCs we used in most of our analyses), were not a good basis for determining relative hospital costs.

Cost Allocation↗